cpu-timers, icount: new modules

refactoring of cpus.c continues with cpu timer state extraction.

cpu-timers: responsible for the softmmu cpu timers state,
            including cpu clocks and ticks.

icount: counts the TCG instructions executed. As such it is specific to
the TCG accelerator. Therefore, it is built only under CONFIG_TCG.

One complication is due to qtest, which uses an icount field to warp time
as part of qtest (qtest_clock_warp).

In order to solve this problem, provide a separate counter for qtest.

This requires fixing assumptions scattered in the code that
qtest_enabled() implies icount_enabled(), checking each specific case.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[remove redundant initialization with qemu_spice_init]
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
[fix lingering calls to icount_get]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/cpu-timers.h

@@ -0,0 +1,87 @@
+/*
+ * CPU timers state API
+ *
+ * Copyright 2020 SUSE LLC
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#ifndef SYSEMU_CPU_TIMERS_H
+#define SYSEMU_CPU_TIMERS_H
+
+#include "qemu/timer.h"
+
+/* init the whole cpu timers API, including icount, ticks, and cpu_throttle */
+void cpu_timers_init(void);
+
+/* icount - Instruction Counter API */
+
+/*
+ * icount enablement state:
+ *
+ * 0 = Disabled - Do not count executed instructions.
+ * 1 = Enabled - Fixed conversion of insn to ns via "shift" option
+ * 2 = Enabled - Runtime adaptive algorithm to compute shift
+ */
+#ifdef CONFIG_TCG
+extern int use_icount;
+#define icount_enabled() (use_icount)
+#else
+#define icount_enabled() 0
+#endif
+
+/*
+ * Update the icount with the executed instructions. Called by
+ * cpus-tcg vCPU thread so the main-loop can see time has moved forward.
+ */
+void cpu_update_icount(CPUState *cpu);
+
+/* get raw icount value */
+int64_t cpu_get_icount_raw(void);
+
+/* return the virtual CPU time in ns, based on the instruction counter. */
+int64_t cpu_get_icount(void);
+/*
+ * convert an instruction counter value to ns, based on the icount shift.
+ * This shift is set as a fixed value with the icount "shift" option
+ * (precise mode), or it is constantly approximated and corrected at
+ * runtime in adaptive mode.
+ */
+int64_t cpu_icount_to_ns(int64_t icount);
+
+/* configure the icount options, including "shift" */
+void configure_icount(QemuOpts *opts, Error **errp);
+
+/* used by tcg vcpu thread to calc icount budget */
+int64_t qemu_icount_round(int64_t count);
+
+/* if the CPUs are idle, start accounting real time to virtual clock. */
+void qemu_start_warp_timer(void);
+void qemu_account_warp_timer(void);
+
+/*
+ * CPU Ticks and Clock
+ */
+
+/* Caller must hold BQL */
+void cpu_enable_ticks(void);
+/* Caller must hold BQL */
+void cpu_disable_ticks(void);
+
+/*
+ * return the time elapsed in VM between vm_start and vm_stop.  Unless
+ * icount is active, cpu_get_ticks() uses units of the host CPU cycle
+ * counter.
+ */
+int64_t cpu_get_ticks(void);
+
+/*
+ * Returns the monotonic time elapsed in VM, i.e.,
+ * the time between vm_start and vm_stop
+ */
+int64_t cpu_get_clock(void);
+
+void qemu_timer_notify_cb(void *opaque, QEMUClockType type);
+
+#endif /* SYSEMU_CPU_TIMERS_H */

include/sysemu/cpus.h

@@ -4,33 +4,23 @@
 #include "qemu/timer.h"
 
 /* cpus.c */
+bool all_cpu_threads_idle(void);
 bool qemu_in_vcpu_thread(void);
 void qemu_init_cpu_loop(void);
 void resume_all_vcpus(void);
 void pause_all_vcpus(void);
 void cpu_stop_current(void);
-void cpu_ticks_init(void);
 
-void configure_icount(QemuOpts *opts, Error **errp);
-extern int use_icount;
 extern int icount_align_option;
 
-/* drift information for info jit command */
-extern int64_t max_delay;
-extern int64_t max_advance;
-void dump_drift_info(void);
-
 /* Unblock cpu */
 void qemu_cpu_kick_self(void);
-void qemu_timer_notify_cb(void *opaque, QEMUClockType type);
 
 void cpu_synchronize_all_states(void);
 void cpu_synchronize_all_post_reset(void);
 void cpu_synchronize_all_post_init(void);
 void cpu_synchronize_all_pre_loadvm(void);
 
-void qtest_clock_warp(int64_t dest);
-
 #ifndef CONFIG_USER_ONLY
 /* vl.c */
 /* *-user doesn't have configurable SMP topology */

include/sysemu/qtest.h

@@ -30,4 +30,6 @@ void qtest_server_set_send_handler(void (*send)(void *, const char *),
                                  void *opaque);
 void qtest_server_inproc_recv(void *opaque, const char *buf);
 
+int64_t qtest_get_virtual_clock(void);
+
 #endif