* futex: support Windows

* qemu-thread: Avoid futex abstraction for non-Linux
 * migration, hw/display/apple-gfx: replace QemuSemaphore with QemuEvent
 * rust: bindings for Error
 * hpet, rust/hpet: return errors from realize if properties are incorrect
 * rust/hpet: Drop BqlCell wrapper for num_timers
 * target/i386: Emulate ftz and denormal flag bits correctly
 * i386/kvm: Prefault memory on page state change
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Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

* futex: support Windows
* qemu-thread: Avoid futex abstraction for non-Linux
* migration, hw/display/apple-gfx: replace QemuSemaphore with QemuEvent
* rust: bindings for Error
* hpet, rust/hpet: return errors from realize if properties are incorrect
* rust/hpet: Drop BqlCell wrapper for num_timers
* target/i386: Emulate ftz and denormal flag bits correctly
* i386/kvm: Prefault memory on page state change

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# -----END PGP SIGNATURE-----
# gpg: Signature made Fri 06 Jun 2025 08:33:12 EDT
# gpg:                using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg:                issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* tag 'for-upstream' of https://gitlab.com/bonzini/qemu: (31 commits)
  tests/tcg/x86_64/fma: add test for exact-denormal output
  target/i386: Wire up MXCSR.DE and FPUS.DE correctly
  target/i386: Use correct type for get_float_exception_flags() values
  target/i386: Detect flush-to-zero after rounding
  hw/display/apple-gfx: Replace QemuSemaphore with QemuEvent
  migration/postcopy: Replace QemuSemaphore with QemuEvent
  migration/colo: Replace QemuSemaphore with QemuEvent
  migration: Replace QemuSemaphore with QemuEvent
  qemu-thread: Document QemuEvent
  qemu-thread: Use futex if available for QemuLockCnt
  qemu-thread: Use futex for QemuEvent on Windows
  qemu-thread: Avoid futex abstraction for non-Linux
  qemu-thread: Replace __linux__ with CONFIG_LINUX
  futex: Support Windows
  futex: Check value after qemu_futex_wait()
  i386/kvm: Prefault memory on page state change
  rust: make TryFrom macro more resilient
  docs: update Rust module status
  rust/hpet: Drop BqlCell wrapper for num_timers
  rust/hpet: return errors from realize if properties are incorrect
  ...

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

accel/kvm/kvm-all.c

@@ -99,6 +99,7 @@ bool kvm_allowed;
 bool kvm_readonly_mem_allowed;
 bool kvm_vm_attributes_allowed;
 bool kvm_msi_use_devid;
+bool kvm_pre_fault_memory_supported;
 static bool kvm_has_guest_debug;
 static int kvm_sstep_flags;
 static bool kvm_immediate_exit;
@@ -2745,6 +2746,7 @@ static int kvm_init(MachineState *ms)
         kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) &&
         kvm_check_extension(s, KVM_CAP_USER_MEMORY2) &&
         (kvm_supported_memory_attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE);
+    kvm_pre_fault_memory_supported = kvm_vm_check_extension(s, KVM_CAP_PRE_FAULT_MEMORY);
 
     if (s->kernel_irqchip_split == ON_OFF_AUTO_AUTO) {
         s->kernel_irqchip_split = mc->default_kernel_irqchip_split ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;

docs/devel/rust.rst

@@ -96,6 +96,11 @@ are missing:
   architecture (VMState).  Right now, VMState lacks type safety because
   it is hard to place the ``VMStateField`` definitions in traits.
 
+* NUL-terminated file names with ``#[track_caller]`` are scheduled for
+  inclusion as ``#![feature(location_file_nul)]``, but it will be a while
+  before QEMU can use them.  For now, there is special code in
+  ``util/error.c`` to support non-NUL-terminated file names.
+
 * associated const equality would be nice to have for some users of
   ``callbacks::FnCall``, but is still experimental.  ``ASSERT_IS_SOME``
   replaces it.
@@ -155,10 +160,10 @@ module           status
 ``callbacks``    complete
 ``cell``         stable
 ``errno``        complete
+``error``        stable
 ``irq``          complete
 ``memory``       stable
 ``module``       complete
-``offset_of``    stable
 ``qdev``         stable
 ``qom``          stable
 ``sysbus``       stable

hw/display/apple-gfx.m

@@ -454,7 +454,7 @@ static void set_cursor_glyph(void *opaque)
 /* ------ DMA (device reading system memory) ------ */
 
 typedef struct AppleGFXReadMemoryJob {
-    QemuSemaphore sem;
+    QemuEvent event;
     hwaddr physical_address;
     uint64_t length;
     void *dst;
@@ -470,7 +470,7 @@ static void apple_gfx_do_read_memory(void *opaque)
                         job->dst, job->length, MEMTXATTRS_UNSPECIFIED);
     job->success = (r == MEMTX_OK);
 
-    qemu_sem_post(&job->sem);
+    qemu_event_set(&job->event);
 }
 
 static bool apple_gfx_read_memory(AppleGFXState *s, hwaddr physical_address,
@@ -483,11 +483,11 @@ static bool apple_gfx_read_memory(AppleGFXState *s, hwaddr physical_address,
     trace_apple_gfx_read_memory(physical_address, length, dst);
 
     /* Performing DMA requires BQL, so do it in a BH. */
-    qemu_sem_init(&job.sem, 0);
+    qemu_event_init(&job.event, 0);
     aio_bh_schedule_oneshot(qemu_get_aio_context(),
                             apple_gfx_do_read_memory, &job);
-    qemu_sem_wait(&job.sem);
+    qemu_event_wait(&job.event);
-    qemu_sem_destroy(&job.sem);
+    qemu_event_destroy(&job.event);
     return job.success;
 }
 

hw/timer/hpet.c

@@ -328,16 +328,16 @@ static const VMStateDescription vmstate_hpet_timer = {
 static const VMStateDescription vmstate_hpet = {
     .name = "hpet",
     .version_id = 2,
-    .minimum_version_id = 1,
+    .minimum_version_id = 2,
     .pre_save = hpet_pre_save,
     .post_load = hpet_post_load,
     .fields = (const VMStateField[]) {
         VMSTATE_UINT64(config, HPETState),
         VMSTATE_UINT64(isr, HPETState),
         VMSTATE_UINT64(hpet_counter, HPETState),
-        VMSTATE_UINT8_V(num_timers_save, HPETState, 2),
+        VMSTATE_UINT8(num_timers_save, HPETState),
         VMSTATE_VALIDATE("num_timers must match", hpet_validate_num_timers),
-        VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0,
+        VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers_save, 0,
                                     vmstate_hpet_timer, HPETTimer),
         VMSTATE_END_OF_LIST()
     },
@@ -691,8 +691,14 @@ static void hpet_realize(DeviceState *dev, Error **errp)
     int i;
     HPETTimer *timer;
 
+    if (s->num_timers < HPET_MIN_TIMERS || s->num_timers > HPET_MAX_TIMERS) {
+        error_setg(errp, "hpet.num_timers must be between %d and %d",
+                   HPET_MIN_TIMERS, HPET_MAX_TIMERS);
+        return;
+    }
     if (!s->intcap) {
-        warn_report("Hpet's intcap not initialized");
+        error_setg(errp, "hpet.hpet-intcap not initialized");
+        return;
     }
     if (hpet_fw_cfg.count == UINT8_MAX) {
         /* first instance */
@@ -700,7 +706,7 @@ static void hpet_realize(DeviceState *dev, Error **errp)
     }
 
     if (hpet_fw_cfg.count == 8) {
-        error_setg(errp, "Only 8 instances of HPET is allowed");
+        error_setg(errp, "Only 8 instances of HPET are allowed");
         return;
     }
 
@@ -710,11 +716,6 @@ static void hpet_realize(DeviceState *dev, Error **errp)
         sysbus_init_irq(sbd, &s->irqs[i]);
     }
 
-    if (s->num_timers < HPET_MIN_TIMERS) {
-        s->num_timers = HPET_MIN_TIMERS;
-    } else if (s->num_timers > HPET_MAX_TIMERS) {
-        s->num_timers = HPET_MAX_TIMERS;
-    }
     for (i = 0; i < HPET_MAX_TIMERS; i++) {
         timer = &s->timer[i];
         timer->qemu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, hpet_timer, timer);

include/qapi/error-internal.h

@@ -0,0 +1,35 @@
+/*
+ * QEMU Error Objects - struct definition
+ *
+ * Copyright IBM, Corp. 2011
+ * Copyright (C) 2011-2015 Red Hat, Inc.
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *  Markus Armbruster <armbru@redhat.com>,
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.  See
+ * the COPYING.LIB file in the top-level directory.
+ */
+
+#ifndef QAPI_ERROR_INTERNAL_H
+
+struct Error
+{
+    char *msg;
+    ErrorClass err_class;
+
+    /* Used for error_abort only, may be NULL. */
+    const char *func;
+
+    /*
+     * src might be NUL-terminated or not.  If it is, src_len is negative.
+     * If it is not, src_len is the length.
+     */
+    const char *src;
+    int src_len;
+    int line;
+    GString *hint;
+};
+
+#endif

include/qemu/futex.h

@@ -1,5 +1,5 @@
 /*
- * Wrappers around Linux futex syscall
+ * Wrappers around Linux futex syscall and similar
  *
  * Copyright Red Hat, Inc. 2017
  *
@@ -11,17 +11,35 @@
  *
  */
 
+/*
+ * Note that a wake-up can also be caused by common futex usage patterns in
+ * unrelated code that happened to have previously used the futex word's
+ * memory location (e.g., typical futex-based implementations of Pthreads
+ * mutexes can cause this under some conditions).  Therefore, qemu_futex_wait()
+ * callers should always conservatively assume that it is a spurious wake-up,
+ * and use the futex word's value (i.e., the user-space synchronization scheme)
+ * to decide whether to continue to block or not.
+ */
+
 #ifndef QEMU_FUTEX_H
 #define QEMU_FUTEX_H
 
+#define HAVE_FUTEX
+
+#ifdef CONFIG_LINUX
 #include <sys/syscall.h>
 #include <linux/futex.h>
 
 #define qemu_futex(...)              syscall(__NR_futex, __VA_ARGS__)
 
-static inline void qemu_futex_wake(void *f, int n)
+static inline void qemu_futex_wake_all(void *f)
 {
-    qemu_futex(f, FUTEX_WAKE, n, NULL, NULL, 0);
+    qemu_futex(f, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
+}
+
+static inline void qemu_futex_wake_single(void *f)
+{
+    qemu_futex(f, FUTEX_WAKE, 1, NULL, NULL, 0);
 }
 
 static inline void qemu_futex_wait(void *f, unsigned val)
@@ -37,5 +55,25 @@ static inline void qemu_futex_wait(void *f, unsigned val)
         }
     }
 }
+#elif defined(CONFIG_WIN32)
+#include <synchapi.h>
+
+static inline void qemu_futex_wake_all(void *f)
+{
+    WakeByAddressAll(f);
+}
+
+static inline void qemu_futex_wake_single(void *f)
+{
+    WakeByAddressSingle(f);
+}
+
+static inline void qemu_futex_wait(void *f, unsigned val)
+{
+    WaitOnAddress(f, &val, sizeof(val), INFINITE);
+}
+#else
+#undef HAVE_FUTEX
+#endif
 
 #endif /* QEMU_FUTEX_H */

include/qemu/lockcnt.h

@@ -17,7 +17,7 @@
 typedef struct QemuLockCnt QemuLockCnt;
 
 struct QemuLockCnt {
-#ifndef CONFIG_LINUX
+#ifndef HAVE_FUTEX
     QemuMutex mutex;
 #endif
     unsigned count;

include/qemu/thread-posix.h

@@ -32,15 +32,6 @@ struct QemuSemaphore {
     unsigned int count;
 };
 
-struct QemuEvent {
-#ifndef __linux__
-    pthread_mutex_t lock;
-    pthread_cond_t cond;
-#endif
-    unsigned value;
-    bool initialized;
-};
-
 struct QemuThread {
     pthread_t thread;
 };

include/qemu/thread-win32.h

@@ -28,12 +28,6 @@ struct QemuSemaphore {
     bool initialized;
 };
 
-struct QemuEvent {
-    int value;
-    HANDLE event;
-    bool initialized;
-};
-
 typedef struct QemuThreadData QemuThreadData;
 struct QemuThread {
     QemuThreadData *data;

include/qemu/thread.h

@@ -3,13 +3,32 @@
 
 #include "qemu/processor.h"
 #include "qemu/atomic.h"
+#include "qemu/futex.h"
 
 typedef struct QemuCond QemuCond;
 typedef struct QemuSemaphore QemuSemaphore;
-typedef struct QemuEvent QemuEvent;
 typedef struct QemuLockCnt QemuLockCnt;
 typedef struct QemuThread QemuThread;
 
+/*
+ * QemuEvent
+ * =========
+ *
+ * QemuEvent is an implementation of Win32 manual-reset event object.
+ * For details, refer to:
+ * https://learn.microsoft.com/en-us/windows/win32/sync/using-event-objects
+ *
+ * QemuEvent is more lightweight than QemuSemaphore when HAVE_FUTEX is defined.
+ */
+typedef struct QemuEvent {
+#ifndef HAVE_FUTEX
+    pthread_mutex_t lock;
+    pthread_cond_t cond;
+#endif
+    unsigned value;
+    bool initialized;
+} QemuEvent;
+
 #ifdef _WIN32
 #include "qemu/thread-win32.h"
 #else

include/system/kvm.h

@@ -42,6 +42,7 @@ extern bool kvm_gsi_routing_allowed;
 extern bool kvm_gsi_direct_mapping;
 extern bool kvm_readonly_mem_allowed;
 extern bool kvm_msi_use_devid;
+extern bool kvm_pre_fault_memory_supported;
 
 #define kvm_enabled()           (kvm_allowed)
 /**

meson.build

@@ -838,11 +838,18 @@ emulator_link_args = []
 midl = not_found
 widl = not_found
 pathcch = not_found
+synchronization = not_found
 host_dsosuf = '.so'
 if host_os == 'windows'
   midl = find_program('midl', required: false)
   widl = find_program('widl', required: false)
   pathcch = cc.find_library('pathcch')
+  synchronization = cc.find_library('Synchronization', required: false)
+  if not synchronization.found()
+    # The library name is lowercase on mingw
+    synchronization = cc.find_library('synchronization', required: true)
+  endif
+
   socket = cc.find_library('ws2_32')
   winmm = cc.find_library('winmm')
 

migration/colo.c

@@ -146,7 +146,7 @@ static void secondary_vm_do_failover(void)
         return;
     }
     /* Notify COLO incoming thread that failover work is finished */
-    qemu_sem_post(&mis->colo_incoming_sem);
+    qemu_event_set(&mis->colo_incoming_event);
 
     /* For Secondary VM, jump to incoming co */
     if (mis->colo_incoming_co) {
@@ -195,7 +195,7 @@ static void primary_vm_do_failover(void)
     }
 
     /* Notify COLO thread that failover work is finished */
-    qemu_sem_post(&s->colo_exit_sem);
+    qemu_event_set(&s->colo_exit_event);
 }
 
 COLOMode get_colo_mode(void)
@@ -620,8 +620,8 @@ out:
     }
 
     /* Hope this not to be too long to wait here */
-    qemu_sem_wait(&s->colo_exit_sem);
+    qemu_event_wait(&s->colo_exit_event);
-    qemu_sem_destroy(&s->colo_exit_sem);
+    qemu_event_destroy(&s->colo_exit_event);
 
     /*
      * It is safe to unregister notifier after failover finished.
@@ -651,7 +651,7 @@ void migrate_start_colo_process(MigrationState *s)
     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
                                 colo_checkpoint_notify_timer, NULL);
 
-    qemu_sem_init(&s->colo_exit_sem, 0);
+    qemu_event_init(&s->colo_exit_event, false);
     colo_process_checkpoint(s);
     bql_lock();
 }
@@ -808,11 +808,11 @@ void colo_shutdown(void)
     case COLO_MODE_PRIMARY:
         s = migrate_get_current();
         qemu_event_set(&s->colo_checkpoint_event);
-        qemu_sem_post(&s->colo_exit_sem);
+        qemu_event_set(&s->colo_exit_event);
         break;
     case COLO_MODE_SECONDARY:
         mis = migration_incoming_get_current();
-        qemu_sem_post(&mis->colo_incoming_sem);
+        qemu_event_set(&mis->colo_incoming_event);
         break;
     default:
         break;
@@ -827,7 +827,7 @@ static void *colo_process_incoming_thread(void *opaque)
     Error *local_err = NULL;
 
     rcu_register_thread();
-    qemu_sem_init(&mis->colo_incoming_sem, 0);
+    qemu_event_init(&mis->colo_incoming_event, false);
 
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                       MIGRATION_STATUS_COLO);
@@ -923,8 +923,8 @@ out:
     }
 
     /* Hope this not to be too long to loop here */
-    qemu_sem_wait(&mis->colo_incoming_sem);
+    qemu_event_wait(&mis->colo_incoming_event);
-    qemu_sem_destroy(&mis->colo_incoming_sem);
+    qemu_event_destroy(&mis->colo_incoming_event);
 
     rcu_unregister_thread();
     return NULL;

migration/migration.c

@@ -1630,7 +1630,7 @@ void migration_cancel(void)
         }
         /* If the migration is paused, kick it out of the pause */
         if (old_state == MIGRATION_STATUS_PRE_SWITCHOVER) {
-            qemu_sem_post(&s->pause_sem);
+            qemu_event_set(&s->pause_event);
         }
         migrate_set_state(&s->state, old_state, MIGRATION_STATUS_CANCELLING);
     } while (s->state != MIGRATION_STATUS_CANCELLING);
@@ -2342,7 +2342,7 @@ void qmp_migrate_continue(MigrationStatus state, Error **errp)
                    MigrationStatus_str(s->state));
         return;
     }
-    qemu_sem_post(&s->pause_sem);
+    qemu_event_set(&s->pause_event);
 }
 
 int migration_rp_wait(MigrationState *s)
@@ -2911,21 +2911,18 @@ static bool migration_switchover_prepare(MigrationState *s)
         return true;
     }
 
-    /* Since leaving this state is not atomic with posting the semaphore
+    /*
+     * Since leaving this state is not atomic with setting the event
      * it's possible that someone could have issued multiple migrate_continue
-     * and the semaphore is incorrectly positive at this point;
+     * and the event is incorrectly set at this point so reset it.
-     * the docs say it's undefined to reinit a semaphore that's already
-     * init'd, so use timedwait to eat up any existing posts.
      */
-    while (qemu_sem_timedwait(&s->pause_sem, 1) == 0) {
+    qemu_event_reset(&s->pause_event);
-        /* This block intentionally left blank */
-    }
 
     /* Update [POSTCOPY_]ACTIVE to PRE_SWITCHOVER */
     migrate_set_state(&s->state, s->state, MIGRATION_STATUS_PRE_SWITCHOVER);
     bql_unlock();
 
-    qemu_sem_wait(&s->pause_sem);
+    qemu_event_wait(&s->pause_event);
 
     bql_lock();
     /*
@@ -4057,7 +4054,7 @@ static void migration_instance_finalize(Object *obj)
     qemu_mutex_destroy(&ms->qemu_file_lock);
     qemu_sem_destroy(&ms->wait_unplug_sem);
     qemu_sem_destroy(&ms->rate_limit_sem);
-    qemu_sem_destroy(&ms->pause_sem);
+    qemu_event_destroy(&ms->pause_event);
     qemu_sem_destroy(&ms->postcopy_pause_sem);
     qemu_sem_destroy(&ms->rp_state.rp_sem);
     qemu_sem_destroy(&ms->rp_state.rp_pong_acks);
@@ -4072,7 +4069,7 @@ static void migration_instance_init(Object *obj)
     ms->state = MIGRATION_STATUS_NONE;
     ms->mbps = -1;
     ms->pages_per_second = -1;
-    qemu_sem_init(&ms->pause_sem, 0);
+    qemu_event_init(&ms->pause_event, false);
     qemu_mutex_init(&ms->error_mutex);
 
     migrate_params_init(&ms->parameters);

migration/migration.h

@@ -98,9 +98,9 @@ struct MigrationIncomingState {
     void (*transport_cleanup)(void *data);
     /*
      * Used to sync thread creations.  Note that we can't create threads in
-     * parallel with this sem.
+     * parallel with this event.
      */
-    QemuSemaphore  thread_sync_sem;
+    QemuEvent  thread_sync_event;
     /*
      * Free at the start of the main state load, set as the main thread finishes
      * loading state.
@@ -186,7 +186,7 @@ struct MigrationIncomingState {
 
     /* The coroutine we should enter (back) after failover */
     Coroutine *colo_incoming_co;
-    QemuSemaphore colo_incoming_sem;
+    QemuEvent colo_incoming_event;
 
     /* Optional load threads pool and its thread exit request flag */
     ThreadPool *load_threads;
@@ -379,10 +379,10 @@ struct MigrationState {
     QemuSemaphore wait_unplug_sem;
 
     /* Migration is paused due to pause-before-switchover */
-    QemuSemaphore pause_sem;
+    QemuEvent pause_event;
 
-    /* The semaphore is used to notify COLO thread that failover is finished */
+    /* The event is used to notify COLO thread that failover is finished */
-    QemuSemaphore colo_exit_sem;
+    QemuEvent colo_exit_event;
 
     /* The event is used to notify COLO thread to do checkpoint */
     QemuEvent colo_checkpoint_event;

migration/postcopy-ram.c

@@ -90,10 +90,10 @@ void postcopy_thread_create(MigrationIncomingState *mis,
                             QemuThread *thread, const char *name,
                             void *(*fn)(void *), int joinable)
 {
-    qemu_sem_init(&mis->thread_sync_sem, 0);
+    qemu_event_init(&mis->thread_sync_event, false);
     qemu_thread_create(thread, name, fn, mis, joinable);
-    qemu_sem_wait(&mis->thread_sync_sem);
+    qemu_event_wait(&mis->thread_sync_event);
-    qemu_sem_destroy(&mis->thread_sync_sem);
+    qemu_event_destroy(&mis->thread_sync_event);
 }
 
 /* Postcopy needs to detect accesses to pages that haven't yet been copied
@@ -964,7 +964,7 @@ static void *postcopy_ram_fault_thread(void *opaque)
     trace_postcopy_ram_fault_thread_entry();
     rcu_register_thread();
     mis->last_rb = NULL; /* last RAMBlock we sent part of */
-    qemu_sem_post(&mis->thread_sync_sem);
+    qemu_event_set(&mis->thread_sync_event);
 
     struct pollfd *pfd;
     size_t pfd_len = 2 + mis->postcopy_remote_fds->len;
@@ -1716,7 +1716,7 @@ void *postcopy_preempt_thread(void *opaque)
 
     rcu_register_thread();
 
-    qemu_sem_post(&mis->thread_sync_sem);
+    qemu_event_set(&mis->thread_sync_event);
 
     /*
      * The preempt channel is established in asynchronous way.  Wait

migration/savevm.c

@@ -2078,7 +2078,7 @@ static void *postcopy_ram_listen_thread(void *opaque)
 
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                                    MIGRATION_STATUS_POSTCOPY_ACTIVE);
-    qemu_sem_post(&mis->thread_sync_sem);
+    qemu_event_set(&mis->thread_sync_event);
     trace_postcopy_ram_listen_thread_start();
 
     rcu_register_thread();

rust/Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "anyhow"
+version = "1.0.98"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
+
 [[package]]
 name = "arbitrary-int"
 version = "1.2.7"
@@ -44,6 +50,15 @@ version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3dca9240753cf90908d7e4aac30f630662b02aebaa1b58a3cadabdb23385b58b"
 
+[[package]]
+name = "foreign"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "17ca1b5be8c9d320daf386f1809c7acc0cb09accbae795c2001953fa50585846"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "hpet"
 version = "0.1.0"
@@ -114,6 +129,8 @@ dependencies = [
 name = "qemu_api"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
+ "foreign",
  "libc",
  "qemu_api_macros",
 ]

rust/Cargo.toml

@@ -67,6 +67,7 @@ missing_safety_doc = "deny"
 mut_mut = "deny"
 needless_bitwise_bool = "deny"
 needless_pass_by_ref_mut = "deny"
+needless_update = "deny"
 no_effect_underscore_binding = "deny"
 option_option = "deny"
 or_fun_call = "deny"

rust/hw/char/pl011/src/device.rs

@@ -175,7 +175,7 @@ impl DeviceImpl for PL011State {
     fn vmsd() -> Option<&'static VMStateDescription> {
         Some(&device_class::VMSTATE_PL011)
     }
-    const REALIZE: Option<fn(&Self)> = Some(Self::realize);
+    const REALIZE: Option<fn(&Self) -> qemu_api::Result<()>> = Some(Self::realize);
 }
 
 impl ResettablePhasesImpl for PL011State {
@@ -619,9 +619,10 @@ impl PL011State {
         }
     }
 
-    fn realize(&self) {
+    fn realize(&self) -> qemu_api::Result<()> {
         self.char_backend
             .enable_handlers(self, Self::can_receive, Self::receive, Self::event);
+        Ok(())
     }
 
     fn reset_hold(&self, _type: ResetType) {

rust/hw/timer/hpet/src/device.rs

@@ -12,7 +12,7 @@ use std::{
 use qemu_api::{
     bindings::{
         address_space_memory, address_space_stl_le, qdev_prop_bit, qdev_prop_bool,
-        qdev_prop_uint32, qdev_prop_uint8,
+        qdev_prop_uint32, qdev_prop_usize,
     },
     cell::{BqlCell, BqlRefCell},
     irq::InterruptSource,
@@ -36,9 +36,9 @@ use crate::fw_cfg::HPETFwConfig;
 const HPET_REG_SPACE_LEN: u64 = 0x400; // 1024 bytes
 
 /// Minimum recommended hardware implementation.
-const HPET_MIN_TIMERS: u8 = 3;
+const HPET_MIN_TIMERS: usize = 3;
 /// Maximum timers in each timer block.
-const HPET_MAX_TIMERS: u8 = 32;
+const HPET_MAX_TIMERS: usize = 32;
 
 /// Flags that HPETState.flags supports.
 const HPET_FLAG_MSI_SUPPORT_SHIFT: usize = 0;
@@ -561,8 +561,8 @@ pub struct HPETState {
 
     /// HPET timer array managed by this timer block.
     #[doc(alias = "timer")]
-    timers: [BqlRefCell<HPETTimer>; HPET_MAX_TIMERS as usize],
+    timers: [BqlRefCell<HPETTimer>; HPET_MAX_TIMERS],
-    num_timers: BqlCell<u8>,
+    num_timers: usize,
     num_timers_save: BqlCell<u8>,
 
     /// Instance id (HPET timer block ID).
@@ -570,11 +570,6 @@ pub struct HPETState {
 }
 
 impl HPETState {
-    // Get num_timers with `usize` type, which is useful to play with array index.
-    fn get_num_timers(&self) -> usize {
-        self.num_timers.get().into()
-    }
-
     const fn has_msi_flag(&self) -> bool {
         self.flags & (1 << HPET_FLAG_MSI_SUPPORT_SHIFT) != 0
     }
@@ -636,7 +631,7 @@ impl HPETState {
             self.hpet_offset
                 .set(ticks_to_ns(self.counter.get()) - CLOCK_VIRTUAL.get_ns());
 
-            for timer in self.timers.iter().take(self.get_num_timers()) {
+            for timer in self.timers.iter().take(self.num_timers) {
                 let mut t = timer.borrow_mut();
 
                 if t.is_int_enabled() && t.is_int_active() {
@@ -648,7 +643,7 @@ impl HPETState {
             // Halt main counter and disable interrupt generation.
             self.counter.set(self.get_ticks());
 
-            for timer in self.timers.iter().take(self.get_num_timers()) {
+            for timer in self.timers.iter().take(self.num_timers) {
                 timer.borrow_mut().del_timer();
             }
         }
@@ -671,7 +666,7 @@ impl HPETState {
         let new_val = val << shift;
         let cleared = new_val & self.int_status.get();
 
-        for (index, timer) in self.timers.iter().take(self.get_num_timers()).enumerate() {
+        for (index, timer) in self.timers.iter().take(self.num_timers).enumerate() {
             if cleared & (1 << index) != 0 {
                 timer.borrow_mut().update_irq(false);
             }
@@ -724,19 +719,17 @@ impl HPETState {
         }
     }
 
-    fn realize(&self) {
+    fn realize(&self) -> qemu_api::Result<()> {
+        if self.num_timers < HPET_MIN_TIMERS || self.num_timers > HPET_MAX_TIMERS {
+            Err(format!(
+                "hpet.num_timers must be between {HPET_MIN_TIMERS} and {HPET_MAX_TIMERS}"
+            ))?;
+        }
         if self.int_route_cap == 0 {
-            // TODO: Add error binding: warn_report()
+            Err("hpet.hpet-intcap property not initialized")?;
-            println!("Hpet's hpet-intcap property not initialized");
         }
 
-        self.hpet_id.set(HPETFwConfig::assign_hpet_id());
+        self.hpet_id.set(HPETFwConfig::assign_hpet_id()?);
-
-        if self.num_timers.get() < HPET_MIN_TIMERS {
-            self.num_timers.set(HPET_MIN_TIMERS);
-        } else if self.num_timers.get() > HPET_MAX_TIMERS {
-            self.num_timers.set(HPET_MAX_TIMERS);
-        }
 
         self.init_timer();
         // 64-bit General Capabilities and ID Register; LegacyReplacementRoute.
@@ -745,16 +738,17 @@ impl HPETState {
             1 << HPET_CAP_COUNT_SIZE_CAP_SHIFT |
             1 << HPET_CAP_LEG_RT_CAP_SHIFT |
             HPET_CAP_VENDER_ID_VALUE << HPET_CAP_VENDER_ID_SHIFT |
-            ((self.get_num_timers() - 1) as u64) << HPET_CAP_NUM_TIM_SHIFT | // indicate the last timer
+            ((self.num_timers - 1) as u64) << HPET_CAP_NUM_TIM_SHIFT | // indicate the last timer
             (HPET_CLK_PERIOD * FS_PER_NS) << HPET_CAP_CNT_CLK_PERIOD_SHIFT, // 10 ns
         );
 
         self.init_gpio_in(2, HPETState::handle_legacy_irq);
         self.init_gpio_out(from_ref(&self.pit_enabled));
+        Ok(())
     }
 
     fn reset_hold(&self, _type: ResetType) {
-        for timer in self.timers.iter().take(self.get_num_timers()) {
+        for timer in self.timers.iter().take(self.num_timers) {
             timer.borrow_mut().reset();
         }
 
@@ -782,7 +776,7 @@ impl HPETState {
             GlobalRegister::try_from(addr).map(HPETRegister::Global)
         } else {
             let timer_id: usize = ((addr - 0x100) / 0x20) as usize;
-            if timer_id <= self.get_num_timers() {
+            if timer_id < self.num_timers {
                 // TODO: Add trace point - trace_hpet_ram_[read|write]_timer_id(timer_id)
                 TimerRegister::try_from(addr & 0x18)
                     .map(|reg| HPETRegister::Timer(&self.timers[timer_id], reg))
@@ -853,12 +847,12 @@ impl HPETState {
          * also added to the migration stream.  Check that it matches the value
          * that was configured.
          */
-        self.num_timers_save.set(self.num_timers.get());
+        self.num_timers_save.set(self.num_timers as u8);
         0
     }
 
     fn post_load(&self, _version_id: u8) -> i32 {
-        for timer in self.timers.iter().take(self.get_num_timers()) {
+        for timer in self.timers.iter().take(self.num_timers) {
             let mut t = timer.borrow_mut();
 
             t.cmp64 = t.calculate_cmp64(t.get_state().counter.get(), t.cmp);
@@ -883,7 +877,7 @@ impl HPETState {
     }
 
     fn validate_num_timers(&self, _version_id: u8) -> bool {
-        self.num_timers.get() == self.num_timers_save.get()
+        self.num_timers == self.num_timers_save.get().into()
     }
 }
 
@@ -910,7 +904,7 @@ qemu_api::declare_properties! {
         c"timers",
         HPETState,
         num_timers,
-        unsafe { &qdev_prop_uint8 },
+        unsafe { &qdev_prop_usize },
         u8,
         default = HPET_MIN_TIMERS
     ),
@@ -1015,16 +1009,16 @@ const VALIDATE_TIMERS_NAME: &CStr = c"num_timers must match";
 static VMSTATE_HPET: VMStateDescription = VMStateDescription {
     name: c"hpet".as_ptr(),
     version_id: 2,
-    minimum_version_id: 1,
+    minimum_version_id: 2,
     pre_save: Some(hpet_pre_save),
     post_load: Some(hpet_post_load),
     fields: vmstate_fields! {
         vmstate_of!(HPETState, config),
         vmstate_of!(HPETState, int_status),
         vmstate_of!(HPETState, counter),
-        vmstate_of!(HPETState, num_timers_save).with_version_id(2),
+        vmstate_of!(HPETState, num_timers_save),
         vmstate_validate!(HPETState, VALIDATE_TIMERS_NAME, HPETState::validate_num_timers),
-        vmstate_struct!(HPETState, timers[0 .. num_timers], &VMSTATE_HPET_TIMER, BqlRefCell<HPETTimer>, HPETState::validate_num_timers).with_version_id(0),
+        vmstate_struct!(HPETState, timers[0 .. num_timers_save], &VMSTATE_HPET_TIMER, BqlRefCell<HPETTimer>, HPETState::validate_num_timers).with_version_id(0),
     },
     subsections: vmstate_subsections! {
         VMSTATE_HPET_RTC_IRQ_LEVEL,
@@ -1042,7 +1036,7 @@ impl DeviceImpl for HPETState {
         Some(&VMSTATE_HPET)
     }
 
-    const REALIZE: Option<fn(&Self)> = Some(Self::realize);
+    const REALIZE: Option<fn(&Self) -> qemu_api::Result<()>> = Some(Self::realize);
 }
 
 impl ResettablePhasesImpl for HPETState {

rust/hw/timer/hpet/src/fw_cfg.rs

@@ -36,7 +36,7 @@ pub static mut hpet_fw_cfg: HPETFwConfig = HPETFwConfig {
 };
 
 impl HPETFwConfig {
-    pub(crate) fn assign_hpet_id() -> usize {
+    pub(crate) fn assign_hpet_id() -> Result<usize, &'static str> {
         assert!(bql_locked());
         // SAFETY: all accesses go through these methods, which guarantee
         // that the accesses are protected by the BQL.
@@ -48,13 +48,12 @@ impl HPETFwConfig {
         }
 
         if fw_cfg.count == 8 {
-            // TODO: Add error binding: error_setg()
+            Err("Only 8 instances of HPET are allowed")?;
-            panic!("Only 8 instances of HPET is allowed");
         }
 
         let id: usize = fw_cfg.count.into();
         fw_cfg.count += 1;
-        id
+        Ok(id)
     }
 
     pub(crate) fn update_hpet_cfg(hpet_id: usize, timer_block_id: u32, address: u64) {

rust/meson.build

@@ -1,9 +1,13 @@
+subproject('anyhow-1-rs', required: true)
 subproject('bilge-0.2-rs', required: true)
 subproject('bilge-impl-0.2-rs', required: true)
+subproject('foreign-0.3-rs', required: true)
 subproject('libc-0.2-rs', required: true)
 
+anyhow_rs = dependency('anyhow-1-rs')
 bilge_rs = dependency('bilge-0.2-rs')
 bilge_impl_rs = dependency('bilge-impl-0.2-rs')
+foreign_rs = dependency('foreign-0.3-rs')
 libc_rs = dependency('libc-0.2-rs')
 
 subproject('proc-macro2-1-rs', required: true)

rust/qemu-api-macros/src/lib.rs

@@ -203,8 +203,8 @@ fn derive_tryinto_body(
     Ok(quote! {
         #(const #discriminants: #repr = #name::#discriminants as #repr;)*;
         match value {
-            #(#discriminants => Ok(#name::#discriminants),)*
+            #(#discriminants => core::result::Result::Ok(#name::#discriminants),)*
-            _ => Err(value),
+            _ => core::result::Result::Err(value),
         }
     })
 }
@@ -236,7 +236,8 @@ fn derive_tryinto_or_error(input: DeriveInput) -> Result<proc_macro2::TokenStrea
         impl core::convert::TryFrom<#repr> for #name {
             type Error = #repr;
 
-            fn try_from(value: #repr) -> Result<Self, Self::Error> {
+            #[allow(ambiguous_associated_items)]
+            fn try_from(value: #repr) -> Result<Self, #repr> {
                 #body
             }
         }

rust/qemu-api/Cargo.toml

@@ -15,7 +15,9 @@ rust-version.workspace = true
 
 [dependencies]
 qemu_api_macros = { path = "../qemu-api-macros" }
+anyhow = "~1.0"
 libc = "0.2.162"
+foreign = "~0.3.1"
 
 [features]
 default = ["debug_cell"]

rust/qemu-api/meson.build

@@ -19,6 +19,7 @@ _qemu_api_rs = static_library(
       'src/cell.rs',
       'src/chardev.rs',
       'src/errno.rs',
+      'src/error.rs',
       'src/irq.rs',
       'src/memory.rs',
       'src/module.rs',
@@ -35,7 +36,7 @@ _qemu_api_rs = static_library(
   override_options: ['rust_std=2021', 'build.rust_std=2021'],
   rust_abi: 'rust',
   rust_args: _qemu_api_cfg,
-  dependencies: [libc_rs, qemu_api_macros, qemuutil_rs,
+  dependencies: [anyhow_rs, foreign_rs, libc_rs, qemu_api_macros, qemuutil_rs,
                  qom, hwcore, chardev, migration],
 )
 

rust/qemu-api/src/error.rs

@@ -0,0 +1,416 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+//! Error propagation for QEMU Rust code
+//!
+//! This module contains [`Error`], the bridge between Rust errors and
+//! [`Result`](std::result::Result)s and QEMU's C [`Error`](bindings::Error)
+//! struct.
+//!
+//! For FFI code, [`Error`] provides functions to simplify conversion between
+//! the Rust ([`Result<>`](std::result::Result)) and C (`Error**`) conventions:
+//!
+//! * [`ok_or_propagate`](crate::Error::ok_or_propagate),
+//!   [`bool_or_propagate`](crate::Error::bool_or_propagate),
+//!   [`ptr_or_propagate`](crate::Error::ptr_or_propagate) can be used to build
+//!   a C return value while also propagating an error condition
+//!
+//! * [`err_or_else`](crate::Error::err_or_else) and
+//!   [`err_or_unit`](crate::Error::err_or_unit) can be used to build a `Result`
+//!
+//! This module is most commonly used at the boundary between C and Rust code;
+//! other code will usually access it through the
+//! [`qemu_api::Result`](crate::Result) type alias, and will use the
+//! [`std::error::Error`] interface to let C errors participate in Rust's error
+//! handling functionality.
+//!
+//! Rust code can also create use this module to create an error object that
+//! will be passed up to C code, though in most cases this will be done
+//! transparently through the `?` operator.  Errors can be constructed from a
+//! simple error string, from an [`anyhow::Error`] to pass any other Rust error
+//! type up to C code, or from a combination of the two.
+//!
+//! The third case, corresponding to [`Error::with_error`], is the only one that
+//! requires mentioning [`qemu_api::Error`](crate::Error) explicitly.  Similar
+//! to how QEMU's C code handles errno values, the string and the
+//! `anyhow::Error` object will be concatenated with `:` as the separator.
+
+use std::{
+    borrow::Cow,
+    ffi::{c_char, c_int, c_void, CStr},
+    fmt::{self, Display},
+    panic, ptr,
+};
+
+use foreign::{prelude::*, OwnedPointer};
+
+use crate::bindings;
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Debug)]
+pub struct Error {
+    msg: Option<Cow<'static, str>>,
+    /// Appends the print string of the error to the msg if not None
+    cause: Option<anyhow::Error>,
+    file: &'static str,
+    line: u32,
+}
+
+impl std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        self.cause.as_ref().map(AsRef::as_ref)
+    }
+
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        self.msg
+            .as_deref()
+            .or_else(|| self.cause.as_deref().map(std::error::Error::description))
+            .expect("no message nor cause?")
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut prefix = "";
+        if let Some(ref msg) = self.msg {
+            write!(f, "{msg}")?;
+            prefix = ": ";
+        }
+        if let Some(ref cause) = self.cause {
+            write!(f, "{prefix}{cause}")?;
+        } else if prefix.is_empty() {
+            panic!("no message nor cause?");
+        }
+        Ok(())
+    }
+}
+
+impl From<String> for Error {
+    #[track_caller]
+    fn from(msg: String) -> Self {
+        let location = panic::Location::caller();
+        Error {
+            msg: Some(Cow::Owned(msg)),
+            cause: None,
+            file: location.file(),
+            line: location.line(),
+        }
+    }
+}
+
+impl From<&'static str> for Error {
+    #[track_caller]
+    fn from(msg: &'static str) -> Self {
+        let location = panic::Location::caller();
+        Error {
+            msg: Some(Cow::Borrowed(msg)),
+            cause: None,
+            file: location.file(),
+            line: location.line(),
+        }
+    }
+}
+
+impl From<anyhow::Error> for Error {
+    #[track_caller]
+    fn from(error: anyhow::Error) -> Self {
+        let location = panic::Location::caller();
+        Error {
+            msg: None,
+            cause: Some(error),
+            file: location.file(),
+            line: location.line(),
+        }
+    }
+}
+
+impl Error {
+    /// Create a new error, prepending `msg` to the
+    /// description of `cause`
+    #[track_caller]
+    pub fn with_error(msg: impl Into<Cow<'static, str>>, cause: impl Into<anyhow::Error>) -> Self {
+        let location = panic::Location::caller();
+        Error {
+            msg: Some(msg.into()),
+            cause: Some(cause.into()),
+            file: location.file(),
+            line: location.line(),
+        }
+    }
+
+    /// Consume a result, returning `false` if it is an error and
+    /// `true` if it is successful.  The error is propagated into
+    /// `errp` like the C API `error_propagate` would do.
+    ///
+    /// # Safety
+    ///
+    /// `errp` must be a valid argument to `error_propagate`;
+    /// typically it is received from C code and need not be
+    /// checked further at the Rust↔C boundary.
+    pub unsafe fn bool_or_propagate(result: Result<()>, errp: *mut *mut bindings::Error) -> bool {
+        // SAFETY: caller guarantees errp is valid
+        unsafe { Self::ok_or_propagate(result, errp) }.is_some()
+    }
+
+    /// Consume a result, returning a `NULL` pointer if it is an error and
+    /// a C representation of the contents if it is successful.  This is
+    /// similar to the C API `error_propagate`, but it panics if `*errp`
+    /// is not `NULL`.
+    ///
+    /// # Safety
+    ///
+    /// `errp` must be a valid argument to `error_propagate`;
+    /// typically it is received from C code and need not be
+    /// checked further at the Rust↔C boundary.
+    ///
+    /// See [`propagate`](Error::propagate) for more information.
+    #[must_use]
+    pub unsafe fn ptr_or_propagate<T: CloneToForeign>(
+        result: Result<T>,
+        errp: *mut *mut bindings::Error,
+    ) -> *mut T::Foreign {
+        // SAFETY: caller guarantees errp is valid
+        unsafe { Self::ok_or_propagate(result, errp) }.clone_to_foreign_ptr()
+    }
+
+    /// Consume a result in the same way as `self.ok()`, but also propagate
+    /// a possible error into `errp`.  This is similar to the C API
+    /// `error_propagate`, but it panics if `*errp` is not `NULL`.
+    ///
+    /// # Safety
+    ///
+    /// `errp` must be a valid argument to `error_propagate`;
+    /// typically it is received from C code and need not be
+    /// checked further at the Rust↔C boundary.
+    ///
+    /// See [`propagate`](Error::propagate) for more information.
+    pub unsafe fn ok_or_propagate<T>(
+        result: Result<T>,
+        errp: *mut *mut bindings::Error,
+    ) -> Option<T> {
+        result.map_err(|err| unsafe { err.propagate(errp) }).ok()
+    }
+
+    /// Equivalent of the C function `error_propagate`.  Fill `*errp`
+    /// with the information container in `self` if `errp` is not NULL;
+    /// then consume it.
+    ///
+    /// This is similar to the C API `error_propagate`, but it panics if
+    /// `*errp` is not `NULL`.
+    ///
+    /// # Safety
+    ///
+    /// `errp` must be a valid argument to `error_propagate`; it can be
+    /// `NULL` or it can point to any of:
+    /// * `error_abort`
+    /// * `error_fatal`
+    /// * a local variable of (C) type `Error *`
+    ///
+    /// Typically `errp` is received from C code and need not be
+    /// checked further at the Rust↔C boundary.
+    pub unsafe fn propagate(self, errp: *mut *mut bindings::Error) {
+        if errp.is_null() {
+            return;
+        }
+
+        // SAFETY: caller guarantees that errp and *errp are valid
+        unsafe {
+            assert_eq!(*errp, ptr::null_mut());
+            bindings::error_propagate(errp, self.clone_to_foreign_ptr());
+        }
+    }
+
+    /// Convert a C `Error*` into a Rust `Result`, using
+    /// `Ok(())` if `c_error` is NULL.  Free the `Error*`.
+    ///
+    /// # Safety
+    ///
+    /// `c_error` must be `NULL` or valid; typically it was initialized
+    /// with `ptr::null_mut()` and passed by reference to a C function.
+    pub unsafe fn err_or_unit(c_error: *mut bindings::Error) -> Result<()> {
+        // SAFETY: caller guarantees c_error is valid
+        unsafe { Self::err_or_else(c_error, || ()) }
+    }
+
+    /// Convert a C `Error*` into a Rust `Result`, calling `f()` to
+    /// obtain an `Ok` value if `c_error` is NULL.  Free the `Error*`.
+    ///
+    /// # Safety
+    ///
+    /// `c_error` must be `NULL` or point to a valid C [`struct
+    /// Error`](bindings::Error); typically it was initialized with
+    /// `ptr::null_mut()` and passed by reference to a C function.
+    pub unsafe fn err_or_else<T, F: FnOnce() -> T>(
+        c_error: *mut bindings::Error,
+        f: F,
+    ) -> Result<T> {
+        // SAFETY: caller guarantees c_error is valid
+        let err = unsafe { Option::<Self>::from_foreign(c_error) };
+        match err {
+            None => Ok(f()),
+            Some(err) => Err(err),
+        }
+    }
+}
+
+impl FreeForeign for Error {
+    type Foreign = bindings::Error;
+
+    unsafe fn free_foreign(p: *mut bindings::Error) {
+        // SAFETY: caller guarantees p is valid
+        unsafe {
+            bindings::error_free(p);
+        }
+    }
+}
+
+impl CloneToForeign for Error {
+    fn clone_to_foreign(&self) -> OwnedPointer<Self> {
+        // SAFETY: all arguments are controlled by this function
+        unsafe {
+            let err: *mut c_void = libc::malloc(std::mem::size_of::<bindings::Error>());
+            let err: &mut bindings::Error = &mut *err.cast();
+            *err = bindings::Error {
+                msg: format!("{self}").clone_to_foreign_ptr(),
+                err_class: bindings::ERROR_CLASS_GENERIC_ERROR,
+                src_len: self.file.len() as c_int,
+                src: self.file.as_ptr().cast::<c_char>(),
+                line: self.line as c_int,
+                func: ptr::null_mut(),
+                hint: ptr::null_mut(),
+            };
+            OwnedPointer::new(err)
+        }
+    }
+}
+
+impl FromForeign for Error {
+    unsafe fn cloned_from_foreign(c_error: *const bindings::Error) -> Self {
+        // SAFETY: caller guarantees c_error is valid
+        unsafe {
+            let error = &*c_error;
+            let file = if error.src_len < 0 {
+                // NUL-terminated
+                CStr::from_ptr(error.src).to_str()
+            } else {
+                // Can become str::from_utf8 with Rust 1.87.0
+                std::str::from_utf8(std::slice::from_raw_parts(
+                    &*error.src.cast::<u8>(),
+                    error.src_len as usize,
+                ))
+            };
+
+            Error {
+                msg: FromForeign::cloned_from_foreign(error.msg),
+                cause: None,
+                file: file.unwrap(),
+                line: error.line as u32,
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::ffi::CStr;
+
+    use anyhow::anyhow;
+    use foreign::OwnedPointer;
+
+    use super::*;
+    use crate::{assert_match, bindings};
+
+    #[track_caller]
+    fn error_for_test(msg: &CStr) -> OwnedPointer<Error> {
+        // SAFETY: all arguments are controlled by this function
+        let location = panic::Location::caller();
+        unsafe {
+            let err: *mut c_void = libc::malloc(std::mem::size_of::<bindings::Error>());
+            let err: &mut bindings::Error = &mut *err.cast();
+            *err = bindings::Error {
+                msg: msg.clone_to_foreign_ptr(),
+                err_class: bindings::ERROR_CLASS_GENERIC_ERROR,
+                src_len: location.file().len() as c_int,
+                src: location.file().as_ptr().cast::<c_char>(),
+                line: location.line() as c_int,
+                func: ptr::null_mut(),
+                hint: ptr::null_mut(),
+            };
+            OwnedPointer::new(err)
+        }
+    }
+
+    unsafe fn error_get_pretty<'a>(local_err: *mut bindings::Error) -> &'a CStr {
+        unsafe { CStr::from_ptr(bindings::error_get_pretty(local_err)) }
+    }
+
+    #[test]
+    #[allow(deprecated)]
+    fn test_description() {
+        use std::error::Error;
+
+        assert_eq!(super::Error::from("msg").description(), "msg");
+        assert_eq!(super::Error::from("msg".to_owned()).description(), "msg");
+    }
+
+    #[test]
+    fn test_display() {
+        assert_eq!(&*format!("{}", Error::from("msg")), "msg");
+        assert_eq!(&*format!("{}", Error::from("msg".to_owned())), "msg");
+        assert_eq!(&*format!("{}", Error::from(anyhow!("msg"))), "msg");
+
+        assert_eq!(
+            &*format!("{}", Error::with_error("msg", anyhow!("cause"))),
+            "msg: cause"
+        );
+    }
+
+    #[test]
+    fn test_bool_or_propagate() {
+        unsafe {
+            let mut local_err: *mut bindings::Error = ptr::null_mut();
+
+            assert!(Error::bool_or_propagate(Ok(()), &mut local_err));
+            assert_eq!(local_err, ptr::null_mut());
+
+            let my_err = Error::from("msg");
+            assert!(!Error::bool_or_propagate(Err(my_err), &mut local_err));
+            assert_ne!(local_err, ptr::null_mut());
+            assert_eq!(error_get_pretty(local_err), c"msg");
+            bindings::error_free(local_err);
+        }
+    }
+
+    #[test]
+    fn test_ptr_or_propagate() {
+        unsafe {
+            let mut local_err: *mut bindings::Error = ptr::null_mut();
+
+            let ret = Error::ptr_or_propagate(Ok("abc".to_owned()), &mut local_err);
+            assert_eq!(String::from_foreign(ret), "abc");
+            assert_eq!(local_err, ptr::null_mut());
+
+            let my_err = Error::from("msg");
+            assert_eq!(
+                Error::ptr_or_propagate(Err::<String, _>(my_err), &mut local_err),
+                ptr::null_mut()
+            );
+            assert_ne!(local_err, ptr::null_mut());
+            assert_eq!(error_get_pretty(local_err), c"msg");
+            bindings::error_free(local_err);
+        }
+    }
+
+    #[test]
+    fn test_err_or_unit() {
+        unsafe {
+            let result = Error::err_or_unit(ptr::null_mut());
+            assert_match!(result, Ok(()));
+
+            let err = error_for_test(c"msg");
+            let err = Error::err_or_unit(err.into_inner()).unwrap_err();
+            assert_eq!(&*format!("{err}"), "msg");
+        }
+    }
+}

rust/qemu-api/src/lib.rs

@@ -19,6 +19,7 @@ pub mod callbacks;
 pub mod cell;
 pub mod chardev;
 pub mod errno;
+pub mod error;
 pub mod irq;
 pub mod memory;
 pub mod module;
@@ -34,6 +35,8 @@ use std::{
     ffi::c_void,
 };
 
+pub use error::{Error, Result};
+
 #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)]
 extern "C" {
     fn g_aligned_alloc0(

rust/qemu-api/src/qdev.rs

@@ -12,10 +12,11 @@ use std::{
 pub use bindings::{ClockEvent, DeviceClass, Property, ResetType};
 
 use crate::{
-    bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, Error, ResettableClass},
+    bindings::{self, qdev_init_gpio_in, qdev_init_gpio_out, ResettableClass},
     callbacks::FnCall,
     cell::{bql_locked, Opaque},
     chardev::Chardev,
+    error::{Error, Result},
     irq::InterruptSource,
     prelude::*,
     qom::{ObjectClass, ObjectImpl, Owned},
@@ -108,7 +109,7 @@ pub trait DeviceImpl: ObjectImpl + ResettablePhasesImpl + IsA<DeviceState> {
     ///
     /// If not `None`, the parent class's `realize` method is overridden
     /// with the function pointed to by `REALIZE`.
-    const REALIZE: Option<fn(&Self)> = None;
+    const REALIZE: Option<fn(&Self) -> Result<()>> = None;
 
     /// An array providing the properties that the user can set on the
     /// device.  Not a `const` because referencing statics in constants
@@ -134,10 +135,13 @@ pub trait DeviceImpl: ObjectImpl + ResettablePhasesImpl + IsA<DeviceState> {
 /// readable/writeable from one thread at any time.
 unsafe extern "C" fn rust_realize_fn<T: DeviceImpl>(
     dev: *mut bindings::DeviceState,
-    _errp: *mut *mut Error,
+    errp: *mut *mut bindings::Error,
 ) {
     let state = NonNull::new(dev).unwrap().cast::<T>();
-    T::REALIZE.unwrap()(unsafe { state.as_ref() });
+    let result = T::REALIZE.unwrap()(unsafe { state.as_ref() });
+    unsafe {
+        Error::ok_or_propagate(result, errp);
+    }
 }
 
 unsafe impl InterfaceType for ResettableClass {

rust/wrapper.h

@@ -60,6 +60,7 @@ typedef enum memory_order {
 #include "hw/qdev-properties-system.h"
 #include "hw/irq.h"
 #include "qapi/error.h"
+#include "qapi/error-internal.h"
 #include "migration/vmstate.h"
 #include "chardev/char-serial.h"
 #include "exec/memattrs.h"

scripts/archive-source.sh

@@ -27,8 +27,9 @@ sub_file="${sub_tdir}/submodule.tar"
 # in their checkout, because the build environment is completely
 # different to the host OS.
 subprojects="keycodemapdb libvfio-user berkeley-softfloat-3
-  berkeley-testfloat-3 arbitrary-int-1-rs bilge-0.2-rs
+  berkeley-testfloat-3 anyhow-1-rs arbitrary-int-1-rs bilge-0.2-rs
-  bilge-impl-0.2-rs either-1-rs itertools-0.11-rs libc-0.2-rs proc-macro2-1-rs
+  bilge-impl-0.2-rs either-1-rs foreign-0.3-rs itertools-0.11-rs
+  libc-0.2-rs proc-macro2-1-rs
   proc-macro-error-1-rs proc-macro-error-attr-1-rs quote-1-rs
   syn-2-rs unicode-ident-1-rs"
 sub_deinit=""

scripts/make-release

@@ -40,8 +40,9 @@ fi
 
 # Only include wraps that are invoked with subproject()
 SUBPROJECTS="libvfio-user keycodemapdb berkeley-softfloat-3
-  berkeley-testfloat-3 arbitrary-int-1-rs bilge-0.2-rs
+  berkeley-testfloat-3 anyhow-1-rs arbitrary-int-1-rs bilge-0.2-rs
-  bilge-impl-0.2-rs either-1-rs itertools-0.11-rs libc-0.2-rs proc-macro2-1-rs
+  bilge-impl-0.2-rs either-1-rs foreign-0.3-rs itertools-0.11-rs
+  libc-0.2-rs proc-macro2-1-rs
   proc-macro-error-1-rs proc-macro-error-attr-1-rs quote-1-rs
   syn-2-rs unicode-ident-1-rs"
 

subprojects/.gitignore

@@ -6,10 +6,12 @@
 /keycodemapdb
 /libvfio-user
 /slirp
+/anyhow-1.0.98
 /arbitrary-int-1.2.7
 /bilge-0.2.0
 /bilge-impl-0.2.0
 /either-1.12.0
+/foreign-0.3.1
 /itertools-0.11.0
 /libc-0.2.162
 /proc-macro-error-1.0.4

subprojects/anyhow-1-rs.wrap

@@ -0,0 +1,7 @@
+[wrap-file]
+directory = anyhow-1.0.98
+source_url = https://crates.io/api/v1/crates/anyhow/1.0.98/download
+source_filename = anyhow-1.0.98.tar.gz
+source_hash = e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487
+#method = cargo
+patch_directory = anyhow-1-rs

subprojects/foreign-0.3-rs.wrap

@@ -0,0 +1,7 @@
+[wrap-file]
+directory = foreign-0.3.1
+source_url = https://crates.io/api/v1/crates/foreign/0.3.1/download
+source_filename = foreign-0.3.1.tar.gz
+source_hash = 17ca1b5be8c9d320daf386f1809c7acc0cb09accbae795c2001953fa50585846
+#method = cargo
+patch_directory = foreign-0.3-rs

subprojects/packagefiles/anyhow-1-rs/meson.build

@@ -0,0 +1,33 @@
+project('anyhow-1-rs', 'rust',
+  meson_version: '>=1.5.0',
+  version: '1.0.98',
+  license: 'MIT OR Apache-2.0',
+  default_options: [])
+
+rustc = meson.get_compiler('rust')
+
+rust_args = ['--cap-lints', 'allow']
+rust_args += ['--cfg', 'feature="std"']
+if rustc.version().version_compare('<1.65.0')
+  error('rustc version ' + rustc.version() + ' is unsupported. Please upgrade to at least 1.65.0')
+endif
+rust_args += [ '--cfg', 'std_backtrace' ] # >= 1.65.0
+if rustc.version().version_compare('<1.81.0')
+  rust_args += [ '--cfg', 'anyhow_no_core_error' ]
+endif
+
+_anyhow_rs = static_library(
+  'anyhow',
+  files('src/lib.rs'),
+  gnu_symbol_visibility: 'hidden',
+  override_options: ['rust_std=2018', 'build.rust_std=2018'],
+  rust_abi: 'rust',
+  rust_args: rust_args,
+  dependencies: [],
+)
+
+anyhow_dep = declare_dependency(
+  link_with: _anyhow_rs,
+)
+
+meson.override_dependency('anyhow-1-rs', anyhow_dep)

subprojects/packagefiles/foreign-0.3-rs/meson.build

@@ -0,0 +1,26 @@
+project('foreign-0.3-rs', 'rust',
+  meson_version: '>=1.5.0',
+  version: '0.2.0',
+  license: 'MIT OR Apache-2.0',
+  default_options: [])
+
+subproject('libc-0.2-rs', required: true)
+libc_rs = dependency('libc-0.2-rs')
+
+_foreign_rs = static_library(
+  'foreign',
+  files('src/lib.rs'),
+  gnu_symbol_visibility: 'hidden',
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  rust_args: [
+    '--cap-lints', 'allow',
+  ],
+  dependencies: [libc_rs],
+)
+
+foreign_dep = declare_dependency(
+  link_with: _foreign_rs,
+)
+
+meson.override_dependency('foreign-0.3-rs', foreign_dep)

target/i386/kvm/kvm.c

@@ -6018,9 +6018,11 @@ static bool host_supports_vmx(void)
  * because private/shared page tracking is already provided through other
  * means, these 2 use-cases should be treated as being mutually-exclusive.
  */
-static int kvm_handle_hc_map_gpa_range(struct kvm_run *run)
+static int kvm_handle_hc_map_gpa_range(X86CPU *cpu, struct kvm_run *run)
 {
+    struct kvm_pre_fault_memory mem;
     uint64_t gpa, size, attributes;
+    int ret;
 
     if (!machine_require_guest_memfd(current_machine))
         return -EINVAL;
@@ -6031,13 +6033,32 @@ static int kvm_handle_hc_map_gpa_range(struct kvm_run *run)
 
     trace_kvm_hc_map_gpa_range(gpa, size, attributes, run->hypercall.flags);
 
-    return kvm_convert_memory(gpa, size, attributes & KVM_MAP_GPA_RANGE_ENCRYPTED);
+    ret = kvm_convert_memory(gpa, size, attributes & KVM_MAP_GPA_RANGE_ENCRYPTED);
+    if (ret || !kvm_pre_fault_memory_supported) {
+        return ret;
+    }
+
+    /*
+     * Opportunistically pre-fault memory in. Failures are ignored so that any
+     * errors in faulting in the memory will get captured in KVM page fault
+     * path when the guest first accesses the page.
+     */
+    memset(&mem, 0, sizeof(mem));
+    mem.gpa = gpa;
+    mem.size = size;
+    while (mem.size) {
+        if (kvm_vcpu_ioctl(CPU(cpu), KVM_PRE_FAULT_MEMORY, &mem)) {
+            break;
+        }
+    }
+
+    return 0;
 }
 
-static int kvm_handle_hypercall(struct kvm_run *run)
+static int kvm_handle_hypercall(X86CPU *cpu, struct kvm_run *run)
 {
     if (run->hypercall.nr == KVM_HC_MAP_GPA_RANGE)
-        return kvm_handle_hc_map_gpa_range(run);
+        return kvm_handle_hc_map_gpa_range(cpu, run);
 
     return -EINVAL;
 }
@@ -6137,7 +6158,7 @@ int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
         break;
 #endif
     case KVM_EXIT_HYPERCALL:
-        ret = kvm_handle_hypercall(run);
+        ret = kvm_handle_hypercall(cpu, run);
         break;
     case KVM_EXIT_SYSTEM_EVENT:
         switch (run->system_event.type) {

target/i386/ops_sse.h

@@ -842,7 +842,7 @@ int64_t helper_cvttsd2sq(CPUX86State *env, ZMMReg *s)
 
 void glue(helper_rsqrtps, SUFFIX)(CPUX86State *env, ZMMReg *d, ZMMReg *s)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     int i;
     for (i = 0; i < 2 << SHIFT; i++) {
         d->ZMM_S(i) = float32_div(float32_one,
@@ -855,7 +855,7 @@ void glue(helper_rsqrtps, SUFFIX)(CPUX86State *env, ZMMReg *d, ZMMReg *s)
 #if SHIFT == 1
 void helper_rsqrtss(CPUX86State *env, ZMMReg *d, ZMMReg *v, ZMMReg *s)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     int i;
     d->ZMM_S(0) = float32_div(float32_one,
                               float32_sqrt(s->ZMM_S(0), &env->sse_status),
@@ -869,7 +869,7 @@ void helper_rsqrtss(CPUX86State *env, ZMMReg *d, ZMMReg *v, ZMMReg *s)
 
 void glue(helper_rcpps, SUFFIX)(CPUX86State *env, ZMMReg *d, ZMMReg *s)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     int i;
     for (i = 0; i < 2 << SHIFT; i++) {
         d->ZMM_S(i) = float32_div(float32_one, s->ZMM_S(i), &env->sse_status);
@@ -880,7 +880,7 @@ void glue(helper_rcpps, SUFFIX)(CPUX86State *env, ZMMReg *d, ZMMReg *s)
 #if SHIFT == 1
 void helper_rcpss(CPUX86State *env, ZMMReg *d, ZMMReg *v, ZMMReg *s)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     int i;
     d->ZMM_S(0) = float32_div(float32_one, s->ZMM_S(0), &env->sse_status);
     for (i = 1; i < 2 << SHIFT; i++) {
@@ -1714,7 +1714,7 @@ void glue(helper_phminposuw, SUFFIX)(CPUX86State *env, Reg *d, Reg *s)
 void glue(helper_roundps, SUFFIX)(CPUX86State *env, Reg *d, Reg *s,
                                   uint32_t mode)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     signed char prev_rounding_mode;
     int i;
 
@@ -1738,7 +1738,7 @@ void glue(helper_roundps, SUFFIX)(CPUX86State *env, Reg *d, Reg *s,
 void glue(helper_roundpd, SUFFIX)(CPUX86State *env, Reg *d, Reg *s,
                                   uint32_t mode)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     signed char prev_rounding_mode;
     int i;
 
@@ -1763,7 +1763,7 @@ void glue(helper_roundpd, SUFFIX)(CPUX86State *env, Reg *d, Reg *s,
 void glue(helper_roundss, SUFFIX)(CPUX86State *env, Reg *d, Reg *v, Reg *s,
                                   uint32_t mode)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     signed char prev_rounding_mode;
     int i;
 
@@ -1788,7 +1788,7 @@ void glue(helper_roundss, SUFFIX)(CPUX86State *env, Reg *d, Reg *v, Reg *s,
 void glue(helper_roundsd, SUFFIX)(CPUX86State *env, Reg *d, Reg *v, Reg *s,
                                   uint32_t mode)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->sse_status);
+    int old_flags = get_float_exception_flags(&env->sse_status);
     signed char prev_rounding_mode;
     int i;
 

target/i386/tcg/fpu_helper.c

@@ -189,25 +189,25 @@ void cpu_init_fp_statuses(CPUX86State *env)
     set_float_default_nan_pattern(0b11000000, &env->mmx_status);
     set_float_default_nan_pattern(0b11000000, &env->sse_status);
     /*
-     * TODO: x86 does flush-to-zero detection after rounding (the SDM
+     * x86 does flush-to-zero detection after rounding (the SDM
      * section 10.2.3.3 on the FTZ bit of MXCSR says that we flush
      * when we detect underflow, which x86 does after rounding).
      */
-    set_float_ftz_detection(float_ftz_before_rounding, &env->fp_status);
+    set_float_ftz_detection(float_ftz_after_rounding, &env->fp_status);
-    set_float_ftz_detection(float_ftz_before_rounding, &env->mmx_status);
+    set_float_ftz_detection(float_ftz_after_rounding, &env->mmx_status);
-    set_float_ftz_detection(float_ftz_before_rounding, &env->sse_status);
+    set_float_ftz_detection(float_ftz_after_rounding, &env->sse_status);
 }
 
-static inline uint8_t save_exception_flags(CPUX86State *env)
+static inline int save_exception_flags(CPUX86State *env)
 {
-    uint8_t old_flags = get_float_exception_flags(&env->fp_status);
+    int old_flags = get_float_exception_flags(&env->fp_status);
     set_float_exception_flags(0, &env->fp_status);
     return old_flags;
 }
 
-static void merge_exception_flags(CPUX86State *env, uint8_t old_flags)
+static void merge_exception_flags(CPUX86State *env, int old_flags)
 {
-    uint8_t new_flags = get_float_exception_flags(&env->fp_status);
+    int new_flags = get_float_exception_flags(&env->fp_status);
     float_raise(old_flags, &env->fp_status);
     fpu_set_exception(env,
                       ((new_flags & float_flag_invalid ? FPUS_IE : 0) |
@@ -215,12 +215,12 @@ static void merge_exception_flags(CPUX86State *env, uint8_t old_flags)
                        (new_flags & float_flag_overflow ? FPUS_OE : 0) |
                        (new_flags & float_flag_underflow ? FPUS_UE : 0) |
                        (new_flags & float_flag_inexact ? FPUS_PE : 0) |
-                       (new_flags & float_flag_input_denormal_flushed ? FPUS_DE : 0)));
+                       (new_flags & float_flag_input_denormal_used ? FPUS_DE : 0)));
 }
 
 static inline floatx80 helper_fdiv(CPUX86State *env, floatx80 a, floatx80 b)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     floatx80 ret = floatx80_div(a, b, &env->fp_status);
     merge_exception_flags(env, old_flags);
     return ret;
@@ -240,7 +240,7 @@ static void fpu_raise_exception(CPUX86State *env, uintptr_t retaddr)
 
 void helper_flds_FT0(CPUX86State *env, uint32_t val)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     union {
         float32 f;
         uint32_t i;
@@ -253,7 +253,7 @@ void helper_flds_FT0(CPUX86State *env, uint32_t val)
 
 void helper_fldl_FT0(CPUX86State *env, uint64_t val)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     union {
         float64 f;
         uint64_t i;
@@ -271,7 +271,7 @@ void helper_fildl_FT0(CPUX86State *env, int32_t val)
 
 void helper_flds_ST0(CPUX86State *env, uint32_t val)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int new_fpstt;
     union {
         float32 f;
@@ -288,7 +288,7 @@ void helper_flds_ST0(CPUX86State *env, uint32_t val)
 
 void helper_fldl_ST0(CPUX86State *env, uint64_t val)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int new_fpstt;
     union {
         float64 f;
@@ -338,7 +338,7 @@ void helper_fildll_ST0(CPUX86State *env, int64_t val)
 
 uint32_t helper_fsts_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     union {
         float32 f;
         uint32_t i;
@@ -351,7 +351,7 @@ uint32_t helper_fsts_ST0(CPUX86State *env)
 
 uint64_t helper_fstl_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     union {
         float64 f;
         uint64_t i;
@@ -364,7 +364,7 @@ uint64_t helper_fstl_ST0(CPUX86State *env)
 
 int32_t helper_fist_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int32_t val;
 
     val = floatx80_to_int32(ST0, &env->fp_status);
@@ -378,7 +378,7 @@ int32_t helper_fist_ST0(CPUX86State *env)
 
 int32_t helper_fistl_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int32_t val;
 
     val = floatx80_to_int32(ST0, &env->fp_status);
@@ -391,7 +391,7 @@ int32_t helper_fistl_ST0(CPUX86State *env)
 
 int64_t helper_fistll_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int64_t val;
 
     val = floatx80_to_int64(ST0, &env->fp_status);
@@ -404,7 +404,7 @@ int64_t helper_fistll_ST0(CPUX86State *env)
 
 int32_t helper_fistt_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int32_t val;
 
     val = floatx80_to_int32_round_to_zero(ST0, &env->fp_status);
@@ -418,7 +418,7 @@ int32_t helper_fistt_ST0(CPUX86State *env)
 
 int32_t helper_fisttl_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int32_t val;
 
     val = floatx80_to_int32_round_to_zero(ST0, &env->fp_status);
@@ -431,7 +431,7 @@ int32_t helper_fisttl_ST0(CPUX86State *env)
 
 int64_t helper_fisttll_ST0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int64_t val;
 
     val = floatx80_to_int64_round_to_zero(ST0, &env->fp_status);
@@ -527,7 +527,7 @@ static const int fcom_ccval[4] = {0x0100, 0x4000, 0x0000, 0x4500};
 
 void helper_fcom_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     FloatRelation ret;
 
     ret = floatx80_compare(ST0, FT0, &env->fp_status);
@@ -537,7 +537,7 @@ void helper_fcom_ST0_FT0(CPUX86State *env)
 
 void helper_fucom_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     FloatRelation ret;
 
     ret = floatx80_compare_quiet(ST0, FT0, &env->fp_status);
@@ -549,7 +549,7 @@ static const int fcomi_ccval[4] = {CC_C, CC_Z, 0, CC_Z | CC_P | CC_C};
 
 void helper_fcomi_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int eflags;
     FloatRelation ret;
 
@@ -562,7 +562,7 @@ void helper_fcomi_ST0_FT0(CPUX86State *env)
 
 void helper_fucomi_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int eflags;
     FloatRelation ret;
 
@@ -575,28 +575,28 @@ void helper_fucomi_ST0_FT0(CPUX86State *env)
 
 void helper_fadd_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST0 = floatx80_add(ST0, FT0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fmul_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST0 = floatx80_mul(ST0, FT0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fsub_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST0 = floatx80_sub(ST0, FT0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fsubr_ST0_FT0(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST0 = floatx80_sub(FT0, ST0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
@@ -615,28 +615,28 @@ void helper_fdivr_ST0_FT0(CPUX86State *env)
 
 void helper_fadd_STN_ST0(CPUX86State *env, int st_index)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST(st_index) = floatx80_add(ST(st_index), ST0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fmul_STN_ST0(CPUX86State *env, int st_index)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST(st_index) = floatx80_mul(ST(st_index), ST0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fsub_STN_ST0(CPUX86State *env, int st_index)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST(st_index) = floatx80_sub(ST(st_index), ST0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fsubr_STN_ST0(CPUX86State *env, int st_index)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST(st_index) = floatx80_sub(ST0, ST(st_index), &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
@@ -861,7 +861,7 @@ void helper_fbld_ST0(CPUX86State *env, target_ulong ptr)
 
 void helper_fbst_ST0(CPUX86State *env, target_ulong ptr)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     int v;
     target_ulong mem_ref, mem_end;
     int64_t val;
@@ -1136,7 +1136,7 @@ static const struct f2xm1_data f2xm1_table[65] = {
 
 void helper_f2xm1(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     uint64_t sig = extractFloatx80Frac(ST0);
     int32_t exp = extractFloatx80Exp(ST0);
     bool sign = extractFloatx80Sign(ST0);
@@ -1369,7 +1369,7 @@ static const struct fpatan_data fpatan_table[9] = {
 
 void helper_fpatan(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     uint64_t arg0_sig = extractFloatx80Frac(ST0);
     int32_t arg0_exp = extractFloatx80Exp(ST0);
     bool arg0_sign = extractFloatx80Sign(ST0);
@@ -1808,7 +1808,7 @@ void helper_fpatan(CPUX86State *env)
 
 void helper_fxtract(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     CPU_LDoubleU temp;
 
     temp.d = ST0;
@@ -1857,7 +1857,7 @@ void helper_fxtract(CPUX86State *env)
 
 static void helper_fprem_common(CPUX86State *env, bool mod)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     uint64_t quotient;
     CPU_LDoubleU temp0, temp1;
     int exp0, exp1, expdiff;
@@ -2053,7 +2053,7 @@ static void helper_fyl2x_common(CPUX86State *env, floatx80 arg, int32_t *exp,
 
 void helper_fyl2xp1(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     uint64_t arg0_sig = extractFloatx80Frac(ST0);
     int32_t arg0_exp = extractFloatx80Exp(ST0);
     bool arg0_sign = extractFloatx80Sign(ST0);
@@ -2151,7 +2151,7 @@ void helper_fyl2xp1(CPUX86State *env)
 
 void helper_fyl2x(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     uint64_t arg0_sig = extractFloatx80Frac(ST0);
     int32_t arg0_exp = extractFloatx80Exp(ST0);
     bool arg0_sign = extractFloatx80Sign(ST0);
@@ -2298,7 +2298,7 @@ void helper_fyl2x(CPUX86State *env)
 
 void helper_fsqrt(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     if (floatx80_is_neg(ST0)) {
         env->fpus &= ~0x4700;  /* (C3,C2,C1,C0) <-- 0000 */
         env->fpus |= 0x400;
@@ -2324,14 +2324,14 @@ void helper_fsincos(CPUX86State *env)
 
 void helper_frndint(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     ST0 = floatx80_round_to_int(ST0, &env->fp_status);
     merge_exception_flags(env, old_flags);
 }
 
 void helper_fscale(CPUX86State *env)
 {
-    uint8_t old_flags = save_exception_flags(env);
+    int old_flags = save_exception_flags(env);
     if (floatx80_invalid_encoding(ST1, &env->fp_status) ||
         floatx80_invalid_encoding(ST0, &env->fp_status)) {
         float_raise(float_flag_invalid, &env->fp_status);
@@ -2369,7 +2369,7 @@ void helper_fscale(CPUX86State *env)
     } else {
         int n;
         FloatX80RoundPrec save = env->fp_status.floatx80_rounding_precision;
-        uint8_t save_flags = get_float_exception_flags(&env->fp_status);
+        int save_flags = get_float_exception_flags(&env->fp_status);
         set_float_exception_flags(0, &env->fp_status);
         n = floatx80_to_int32_round_to_zero(ST1, &env->fp_status);
         set_float_exception_flags(save_flags, &env->fp_status);
@@ -3254,6 +3254,7 @@ void update_mxcsr_status(CPUX86State *env)
 
     /* Set exception flags.  */
     set_float_exception_flags((mxcsr & FPUS_IE ? float_flag_invalid : 0) |
+                              (mxcsr & FPUS_DE ? float_flag_input_denormal_used : 0) |
                               (mxcsr & FPUS_ZE ? float_flag_divbyzero : 0) |
                               (mxcsr & FPUS_OE ? float_flag_overflow : 0) |
                               (mxcsr & FPUS_UE ? float_flag_underflow : 0) |
@@ -3269,15 +3270,9 @@ void update_mxcsr_status(CPUX86State *env)
 
 void update_mxcsr_from_sse_status(CPUX86State *env)
 {
-    uint8_t flags = get_float_exception_flags(&env->sse_status);
+    int flags = get_float_exception_flags(&env->sse_status);
-    /*
-     * The MXCSR denormal flag has opposite semantics to
-     * float_flag_input_denormal_flushed (the softfloat code sets that flag
-     * only when flushing input denormals to zero, but SSE sets it
-     * only when not flushing them to zero), so is not converted
-     * here.
-     */
     env->mxcsr |= ((flags & float_flag_invalid ? FPUS_IE : 0) |
+                   (flags & float_flag_input_denormal_used ? FPUS_DE : 0) |
                    (flags & float_flag_divbyzero ? FPUS_ZE : 0) |
                    (flags & float_flag_overflow ? FPUS_OE : 0) |
                    (flags & float_flag_underflow ? FPUS_UE : 0) |

tests/tcg/x86_64/fma.c

@@ -79,14 +79,21 @@ static testdata tests[] = {
     /*
      * Flushing of denormal outputs to zero should also happen after
      * rounding, so setting FTZ should not affect the result or the flags.
-     * QEMU currently does not emulate this correctly because we do the
-     * flush-to-zero check before rounding, so we incorrectly produce a
-     * zero result and set Underflow as well as Precision.
      */
-#ifdef ENABLE_FAILING_TESTS
     { 0x3fdfffffffffffff, 0x001fffffffffffff, 0x801fffffffffffff, true,
       0x8010000000000000, 0x20 }, /* Enabling FTZ shouldn't change flags */
-#endif
+    /*
+     * normal * 0 + a denormal. With FTZ disabled this gives an exact
+     * result (equal to the input denormal) that has consumed the denormal.
+     */
+    { 0x3cc8000000000000, 0x0000000000000000, 0x8008000000000000, false,
+      0x8008000000000000, 0x2 }, /* Denormal */
+    /*
+     * With FTZ enabled, this consumes the denormal, returns zero (because
+     * flushed) and indicates also Underflow and Precision.
+     */
+    { 0x3cc8000000000000, 0x0000000000000000, 0x8008000000000000, true,
+      0x8000000000000000, 0x32 }, /* Precision, Underflow, Denormal */
 };
 
 int main(void)

tests/unit/test-aio-multithread.c

@@ -305,7 +305,9 @@ static void mcs_mutex_lock(void)
     prev = qatomic_xchg(&mutex_head, id);
     if (prev != -1) {
         qatomic_set(&nodes[prev].next, id);
-        qemu_futex_wait(&nodes[id].locked, 1);
+        while (qatomic_read(&nodes[id].locked) == 1) {
+            qemu_futex_wait(&nodes[id].locked, 1);
+        }
     }
 }
 
@@ -328,7 +330,7 @@ static void mcs_mutex_unlock(void)
     /* Wake up the next in line.  */
     next = qatomic_read(&nodes[id].next);
     nodes[next].locked = 0;
-    qemu_futex_wake(&nodes[next].locked, 1);
+    qemu_futex_wake_single(&nodes[next].locked);
 }
 
 static void test_multi_fair_mutex_entry(void *opaque)

util/error.c

@@ -15,15 +15,7 @@
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
-
+#include "qapi/error-internal.h"
-struct Error
-{
-    char *msg;
-    ErrorClass err_class;
-    const char *src, *func;
-    int line;
-    GString *hint;
-};
 
 Error *error_abort;
 Error *error_fatal;
@@ -32,8 +24,13 @@ Error *error_warn;
 static void error_handle(Error **errp, Error *err)
 {
     if (errp == &error_abort) {
-        fprintf(stderr, "Unexpected error in %s() at %s:%d:\n",
+        if (err->func) {
-                err->func, err->src, err->line);
+            fprintf(stderr, "Unexpected error in %s() at %.*s:%d:\n",
+                    err->func, err->src_len, err->src, err->line);
+        } else {
+            fprintf(stderr, "Unexpected error at %.*s:%d:\n",
+		    err->src_len, err->src, err->line);
+        }
         error_report("%s", error_get_pretty(err));
         if (err->hint) {
             error_printf("%s", err->hint->str);
@@ -75,6 +72,7 @@ static void error_setv(Error **errp,
         g_free(msg);
     }
     err->err_class = err_class;
+    err->src_len = -1;
     err->src = src;
     err->line = line;
     err->func = func;

util/event.c

@@ -0,0 +1,171 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "qemu/osdep.h"
+#include "qemu/thread.h"
+
+/*
+ * Valid transitions:
+ * - FREE -> SET (qemu_event_set)
+ * - BUSY -> SET (qemu_event_set)
+ * - SET -> FREE (qemu_event_reset)
+ * - FREE -> BUSY (qemu_event_wait)
+ *
+ * With futex, the waking and blocking operations follow
+ * BUSY -> SET and FREE -> BUSY, respectively.
+ *
+ * Without futex, BUSY -> SET and FREE -> BUSY never happen. Instead, the waking
+ * operation follows FREE -> SET and the blocking operation will happen in
+ * qemu_event_wait() if the event is not SET.
+ *
+ * SET->BUSY does not happen (it can be observed from the outside but
+ * it really is SET->FREE->BUSY).
+ *
+ * busy->free provably cannot happen; to enforce it, the set->free transition
+ * is done with an OR, which becomes a no-op if the event has concurrently
+ * transitioned to free or busy.
+ */
+
+#define EV_SET         0
+#define EV_FREE        1
+#define EV_BUSY       -1
+
+void qemu_event_init(QemuEvent *ev, bool init)
+{
+#ifndef HAVE_FUTEX
+    pthread_mutex_init(&ev->lock, NULL);
+    pthread_cond_init(&ev->cond, NULL);
+#endif
+
+    ev->value = (init ? EV_SET : EV_FREE);
+    ev->initialized = true;
+}
+
+void qemu_event_destroy(QemuEvent *ev)
+{
+    assert(ev->initialized);
+    ev->initialized = false;
+#ifndef HAVE_FUTEX
+    pthread_mutex_destroy(&ev->lock);
+    pthread_cond_destroy(&ev->cond);
+#endif
+}
+
+void qemu_event_set(QemuEvent *ev)
+{
+    assert(ev->initialized);
+
+#ifdef HAVE_FUTEX
+    /*
+     * Pairs with both qemu_event_reset() and qemu_event_wait().
+     *
+     * qemu_event_set has release semantics, but because it *loads*
+     * ev->value we need a full memory barrier here.
+     */
+    smp_mb();
+    if (qatomic_read(&ev->value) != EV_SET) {
+        int old = qatomic_xchg(&ev->value, EV_SET);
+
+        /* Pairs with memory barrier in kernel futex_wait system call.  */
+        smp_mb__after_rmw();
+        if (old == EV_BUSY) {
+            /* There were waiters, wake them up.  */
+            qemu_futex_wake_all(ev);
+        }
+    }
+#else
+    pthread_mutex_lock(&ev->lock);
+    /* Pairs with qemu_event_reset()'s load acquire.  */
+    qatomic_store_release(&ev->value, EV_SET);
+    pthread_cond_broadcast(&ev->cond);
+    pthread_mutex_unlock(&ev->lock);
+#endif
+}
+
+void qemu_event_reset(QemuEvent *ev)
+{
+    assert(ev->initialized);
+
+#ifdef HAVE_FUTEX
+    /*
+     * If there was a concurrent reset (or even reset+wait),
+     * do nothing.  Otherwise change EV_SET->EV_FREE.
+     */
+    qatomic_or(&ev->value, EV_FREE);
+
+    /*
+     * Order reset before checking the condition in the caller.
+     * Pairs with the first memory barrier in qemu_event_set().
+     */
+    smp_mb__after_rmw();
+#else
+    /*
+     * If futexes are not available, there are no EV_FREE->EV_BUSY
+     * transitions because wakeups are done entirely through the
+     * condition variable.  Since qatomic_set() only writes EV_FREE,
+     * the load seems useless but in reality, the acquire synchronizes
+     * with qemu_event_set()'s store release: if qemu_event_reset()
+     * sees EV_SET here, then the caller will certainly see a
+     * successful condition and skip qemu_event_wait():
+     *
+     * done = 1;                 if (done == 0)
+     * qemu_event_set() {          qemu_event_reset() {
+     *   lock();
+     *   ev->value = EV_SET ----->     load ev->value
+     *                                 ev->value = old value | EV_FREE
+     *   cond_broadcast()
+     *   unlock();                 }
+     * }                           if (done == 0)
+     *                               // qemu_event_wait() not called
+     */
+    qatomic_set(&ev->value, qatomic_load_acquire(&ev->value) | EV_FREE);
+#endif
+}
+
+void qemu_event_wait(QemuEvent *ev)
+{
+    assert(ev->initialized);
+
+#ifdef HAVE_FUTEX
+    while (true) {
+        /*
+         * qemu_event_wait must synchronize with qemu_event_set even if it does
+         * not go down the slow path, so this load-acquire is needed that
+         * synchronizes with the first memory barrier in qemu_event_set().
+         */
+        unsigned value = qatomic_load_acquire(&ev->value);
+        if (value == EV_SET) {
+            break;
+        }
+
+        if (value == EV_FREE) {
+            /*
+             * Leave the event reset and tell qemu_event_set that there are
+             * waiters.  No need to retry, because there cannot be a concurrent
+             * busy->free transition.  After the CAS, the event will be either
+             * set or busy.
+             *
+             * This cmpxchg doesn't have particular ordering requirements if it
+             * succeeds (moving the store earlier can only cause
+             * qemu_event_set() to issue _more_ wakeups), the failing case needs
+             * acquire semantics like the load above.
+             */
+            if (qatomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
+                break;
+            }
+        }
+
+        /*
+         * This is the final check for a concurrent set, so it does need
+         * a smp_mb() pairing with the second barrier of qemu_event_set().
+         * The barrier is inside the FUTEX_WAIT system call.
+         */
+        qemu_futex_wait(ev, EV_BUSY);
+    }
+#else
+    pthread_mutex_lock(&ev->lock);
+    while (qatomic_read(&ev->value) != EV_SET) {
+        pthread_cond_wait(&ev->cond, &ev->lock);
+    }
+    pthread_mutex_unlock(&ev->lock);
+#endif
+}

util/lockcnt.c

@@ -12,10 +12,11 @@
 #include "qemu/atomic.h"
 #include "trace.h"
 
-#ifdef CONFIG_LINUX
+#ifdef HAVE_FUTEX
-#include "qemu/futex.h"
 
-/* On Linux, bits 0-1 are a futex-based lock, bits 2-31 are the counter.
+/*
+ * When futex is available, bits 0-1 are a futex-based lock, bits 2-31 are the
+ * counter.
  * For the mutex algorithm see Ulrich Drepper's "Futexes Are Tricky" (ok,
  * this is not the most relaxing citation I could make...).  It is similar
  * to mutex2 in the paper.
@@ -106,7 +107,7 @@ static bool qemu_lockcnt_cmpxchg_or_wait(QemuLockCnt *lockcnt, int *val,
 static void lockcnt_wake(QemuLockCnt *lockcnt)
 {
     trace_lockcnt_futex_wake(lockcnt);
-    qemu_futex_wake(&lockcnt->count, 1);
+    qemu_futex_wake_single(&lockcnt->count);
 }
 
 void qemu_lockcnt_inc(QemuLockCnt *lockcnt)

util/meson.build

@@ -27,7 +27,7 @@ else
   util_ss.add(files('event_notifier-win32.c'))
   util_ss.add(files('oslib-win32.c'))
   util_ss.add(files('qemu-thread-win32.c'))
-  util_ss.add(winmm, pathcch)
+  util_ss.add(winmm, pathcch, synchronization)
 endif
 util_ss.add(when: linux_io_uring, if_true: files('fdmon-io_uring.c'))
 if glib_has_gslice
@@ -35,6 +35,7 @@ if glib_has_gslice
 endif
 util_ss.add(files('defer-call.c'))
 util_ss.add(files('envlist.c', 'path.c', 'module.c'))
+util_ss.add(files('event.c'))
 util_ss.add(files('host-utils.c'))
 util_ss.add(files('bitmap.c', 'bitops.c'))
 util_ss.add(files('fifo8.c'))

util/qemu-thread-posix.c

@@ -317,154 +317,6 @@ void qemu_sem_wait(QemuSemaphore *sem)
     qemu_mutex_unlock(&sem->mutex);
 }
 
-#ifdef __linux__
-#include "qemu/futex.h"
-#else
-static inline void qemu_futex_wake(QemuEvent *ev, int n)
-{
-    assert(ev->initialized);
-    pthread_mutex_lock(&ev->lock);
-    if (n == 1) {
-        pthread_cond_signal(&ev->cond);
-    } else {
-        pthread_cond_broadcast(&ev->cond);
-    }
-    pthread_mutex_unlock(&ev->lock);
-}
-
-static inline void qemu_futex_wait(QemuEvent *ev, unsigned val)
-{
-    assert(ev->initialized);
-    pthread_mutex_lock(&ev->lock);
-    if (ev->value == val) {
-        pthread_cond_wait(&ev->cond, &ev->lock);
-    }
-    pthread_mutex_unlock(&ev->lock);
-}
-#endif
-
-/* Valid transitions:
- * - free->set, when setting the event
- * - busy->set, when setting the event, followed by qemu_futex_wake
- * - set->free, when resetting the event
- * - free->busy, when waiting
- *
- * set->busy does not happen (it can be observed from the outside but
- * it really is set->free->busy).
- *
- * busy->free provably cannot happen; to enforce it, the set->free transition
- * is done with an OR, which becomes a no-op if the event has concurrently
- * transitioned to free or busy.
- */
-
-#define EV_SET         0
-#define EV_FREE        1
-#define EV_BUSY       -1
-
-void qemu_event_init(QemuEvent *ev, bool init)
-{
-#ifndef __linux__
-    pthread_mutex_init(&ev->lock, NULL);
-    pthread_cond_init(&ev->cond, NULL);
-#endif
-
-    ev->value = (init ? EV_SET : EV_FREE);
-    ev->initialized = true;
-}
-
-void qemu_event_destroy(QemuEvent *ev)
-{
-    assert(ev->initialized);
-    ev->initialized = false;
-#ifndef __linux__
-    pthread_mutex_destroy(&ev->lock);
-    pthread_cond_destroy(&ev->cond);
-#endif
-}
-
-void qemu_event_set(QemuEvent *ev)
-{
-    assert(ev->initialized);
-
-    /*
-     * Pairs with both qemu_event_reset() and qemu_event_wait().
-     *
-     * qemu_event_set has release semantics, but because it *loads*
-     * ev->value we need a full memory barrier here.
-     */
-    smp_mb();
-    if (qatomic_read(&ev->value) != EV_SET) {
-        int old = qatomic_xchg(&ev->value, EV_SET);
-
-        /* Pairs with memory barrier in kernel futex_wait system call.  */
-        smp_mb__after_rmw();
-        if (old == EV_BUSY) {
-            /* There were waiters, wake them up.  */
-            qemu_futex_wake(ev, INT_MAX);
-        }
-    }
-}
-
-void qemu_event_reset(QemuEvent *ev)
-{
-    assert(ev->initialized);
-
-    /*
-     * If there was a concurrent reset (or even reset+wait),
-     * do nothing.  Otherwise change EV_SET->EV_FREE.
-     */
-    qatomic_or(&ev->value, EV_FREE);
-
-    /*
-     * Order reset before checking the condition in the caller.
-     * Pairs with the first memory barrier in qemu_event_set().
-     */
-    smp_mb__after_rmw();
-}
-
-void qemu_event_wait(QemuEvent *ev)
-{
-    unsigned value;
-
-    assert(ev->initialized);
-
-    /*
-     * qemu_event_wait must synchronize with qemu_event_set even if it does
-     * not go down the slow path, so this load-acquire is needed that
-     * synchronizes with the first memory barrier in qemu_event_set().
-     *
-     * If we do go down the slow path, there is no requirement at all: we
-     * might miss a qemu_event_set() here but ultimately the memory barrier in
-     * qemu_futex_wait() will ensure the check is done correctly.
-     */
-    value = qatomic_load_acquire(&ev->value);
-    if (value != EV_SET) {
-        if (value == EV_FREE) {
-            /*
-             * Leave the event reset and tell qemu_event_set that there are
-             * waiters.  No need to retry, because there cannot be a concurrent
-             * busy->free transition.  After the CAS, the event will be either
-             * set or busy.
-             *
-             * This cmpxchg doesn't have particular ordering requirements if it
-             * succeeds (moving the store earlier can only cause qemu_event_set()
-             * to issue _more_ wakeups), the failing case needs acquire semantics
-             * like the load above.
-             */
-            if (qatomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
-                return;
-            }
-        }
-
-        /*
-         * This is the final check for a concurrent set, so it does need
-         * a smp_mb() pairing with the second barrier of qemu_event_set().
-         * The barrier is inside the FUTEX_WAIT system call.
-         */
-        qemu_futex_wait(ev, EV_BUSY);
-    }
-}
-
 static __thread NotifierList thread_exit;
 
 /*

util/qemu-thread-win32.c

@@ -231,135 +231,6 @@ void qemu_sem_wait(QemuSemaphore *sem)
     }
 }
 
-/* Wrap a Win32 manual-reset event with a fast userspace path.  The idea
- * is to reset the Win32 event lazily, as part of a test-reset-test-wait
- * sequence.  Such a sequence is, indeed, how QemuEvents are used by
- * RCU and other subsystems!
- *
- * Valid transitions:
- * - free->set, when setting the event
- * - busy->set, when setting the event, followed by SetEvent
- * - set->free, when resetting the event
- * - free->busy, when waiting
- *
- * set->busy does not happen (it can be observed from the outside but
- * it really is set->free->busy).
- *
- * busy->free provably cannot happen; to enforce it, the set->free transition
- * is done with an OR, which becomes a no-op if the event has concurrently
- * transitioned to free or busy (and is faster than cmpxchg).
- */
-
-#define EV_SET         0
-#define EV_FREE        1
-#define EV_BUSY       -1
-
-void qemu_event_init(QemuEvent *ev, bool init)
-{
-    /* Manual reset.  */
-    ev->event = CreateEvent(NULL, TRUE, TRUE, NULL);
-    ev->value = (init ? EV_SET : EV_FREE);
-    ev->initialized = true;
-}
-
-void qemu_event_destroy(QemuEvent *ev)
-{
-    assert(ev->initialized);
-    ev->initialized = false;
-    CloseHandle(ev->event);
-}
-
-void qemu_event_set(QemuEvent *ev)
-{
-    assert(ev->initialized);
-
-    /*
-     * Pairs with both qemu_event_reset() and qemu_event_wait().
-     *
-     * qemu_event_set has release semantics, but because it *loads*
-     * ev->value we need a full memory barrier here.
-     */
-    smp_mb();
-    if (qatomic_read(&ev->value) != EV_SET) {
-        int old = qatomic_xchg(&ev->value, EV_SET);
-
-        /* Pairs with memory barrier after ResetEvent.  */
-        smp_mb__after_rmw();
-        if (old == EV_BUSY) {
-            /* There were waiters, wake them up.  */
-            SetEvent(ev->event);
-        }
-    }
-}
-
-void qemu_event_reset(QemuEvent *ev)
-{
-    assert(ev->initialized);
-
-    /*
-     * If there was a concurrent reset (or even reset+wait),
-     * do nothing.  Otherwise change EV_SET->EV_FREE.
-     */
-    qatomic_or(&ev->value, EV_FREE);
-
-    /*
-     * Order reset before checking the condition in the caller.
-     * Pairs with the first memory barrier in qemu_event_set().
-     */
-    smp_mb__after_rmw();
-}
-
-void qemu_event_wait(QemuEvent *ev)
-{
-    unsigned value;
-
-    assert(ev->initialized);
-
-    /*
-     * qemu_event_wait must synchronize with qemu_event_set even if it does
-     * not go down the slow path, so this load-acquire is needed that
-     * synchronizes with the first memory barrier in qemu_event_set().
-     *
-     * If we do go down the slow path, there is no requirement at all: we
-     * might miss a qemu_event_set() here but ultimately the memory barrier in
-     * qemu_futex_wait() will ensure the check is done correctly.
-     */
-    value = qatomic_load_acquire(&ev->value);
-    if (value != EV_SET) {
-        if (value == EV_FREE) {
-            /*
-             * Here the underlying kernel event is reset, but qemu_event_set is
-             * not yet going to call SetEvent.  However, there will be another
-             * check for EV_SET below when setting EV_BUSY.  At that point it
-             * is safe to call WaitForSingleObject.
-             */
-            ResetEvent(ev->event);
-
-            /*
-             * It is not clear whether ResetEvent provides this barrier; kernel
-             * APIs (KeResetEvent/KeClearEvent) do not.  Better safe than sorry!
-             */
-            smp_mb();
-
-            /*
-             * Leave the event reset and tell qemu_event_set that there are
-             * waiters.  No need to retry, because there cannot be a concurrent
-             * busy->free transition.  After the CAS, the event will be either
-             * set or busy.
-             */
-            if (qatomic_cmpxchg(&ev->value, EV_FREE, EV_BUSY) == EV_SET) {
-                return;
-            }
-        }
-
-        /*
-         * ev->value is now EV_BUSY.  Since we didn't observe EV_SET,
-         * qemu_event_set() must observe EV_BUSY and call SetEvent().
-         */
-        WaitForSingleObject(ev->event, INFINITE);
-    }
-}
-
 struct QemuThreadData {
     /* Passed to win32_start_routine.  */
     void             *(*start_routine)(void *);