Replace qemu_real_host_page variables with inlined functions

Replace the global variables with inlined helper functions. getpagesize() is very
likely annotated with a "const" function attribute (at least with glibc), and thus
optimization should apply even better.

This avoids the need for a constructor initialization too.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220323155743.1585078-12-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

util/cutils.c

@@ -175,7 +175,7 @@ int qemu_fdatasync(int fd)
 int qemu_msync(void *addr, size_t length, int fd)
 {
 #ifdef CONFIG_POSIX
-    size_t align_mask = ~(qemu_real_host_page_size - 1);
+    size_t align_mask = ~(qemu_real_host_page_size() - 1);
 
     /**
      * There are no strict reqs as per the length of mapping
@@ -183,7 +183,7 @@ int qemu_msync(void *addr, size_t length, int fd)
      * alignment changes. Additionally - round the size to the multiple
      * of PAGE_SIZE
      */
-    length += ((uintptr_t)addr & (qemu_real_host_page_size - 1));
+    length += ((uintptr_t)addr & (qemu_real_host_page_size() - 1));
     length = (length + ~align_mask) & align_mask;
 
     addr = (void *)((uintptr_t)addr & align_mask);

util/meson.build

@@ -42,7 +42,6 @@ if have_membarrier
   util_ss.add(files('sys_membarrier.c'))
 endif
 util_ss.add(files('log.c'))
-util_ss.add(files('pagesize.c'))
 util_ss.add(files('qdist.c'))
 util_ss.add(files('qht.c'))
 util_ss.add(files('qsp.c'))

util/mmap-alloc.c

@@ -50,7 +50,7 @@ size_t qemu_fd_getpagesize(int fd)
 #endif
 #endif
 
-    return qemu_real_host_page_size;
+    return qemu_real_host_page_size();
 }
 
 size_t qemu_mempath_getpagesize(const char *mem_path)
@@ -81,7 +81,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path)
 #endif
 #endif
 
-    return qemu_real_host_page_size;
+    return qemu_real_host_page_size();
 }
 
 #define OVERCOMMIT_MEMORY_PATH "/proc/sys/vm/overcommit_memory"
@@ -101,7 +101,7 @@ static bool map_noreserve_effective(int fd, uint32_t qemu_map_flags)
      *    MAP_NORESERVE.
      * b) MAP_NORESERVE is not affected by /proc/sys/vm/overcommit_memory.
      */
-    if (qemu_fd_getpagesize(fd) != qemu_real_host_page_size) {
+    if (qemu_fd_getpagesize(fd) != qemu_real_host_page_size()) {
         return true;
     }
 
@@ -166,7 +166,7 @@ static void *mmap_reserve(size_t size, int fd)
      * We do this unless we are using the system page size, in which case
      * anonymous memory is OK.
      */
-    if (fd == -1 || qemu_fd_getpagesize(fd) == qemu_real_host_page_size) {
+    if (fd == -1 || qemu_fd_getpagesize(fd) == qemu_real_host_page_size()) {
         fd = -1;
         flags |= MAP_ANONYMOUS;
     } else {
@@ -243,7 +243,7 @@ static inline size_t mmap_guard_pagesize(int fd)
     /* Mappings in the same segment must share the same page size */
     return qemu_fd_getpagesize(fd);
 #else
-    return qemu_real_host_page_size;
+    return qemu_real_host_page_size();
 #endif
 }
 

util/osdep.c

@@ -69,8 +69,8 @@ int qemu_madvise(void *addr, size_t len, int advice)
 
 static int qemu_mprotect__osdep(void *addr, size_t size, int prot)
 {
-    g_assert(!((uintptr_t)addr & ~qemu_real_host_page_mask));
-    g_assert(!(size & ~qemu_real_host_page_mask));
+    g_assert(!((uintptr_t)addr & ~qemu_real_host_page_mask()));
+    g_assert(!(size & ~qemu_real_host_page_mask()));
 
 #ifdef _WIN32
     DWORD old_protect;

util/oslib-posix.c

@@ -767,7 +767,7 @@ void *qemu_alloc_stack(size_t *sz)
 #ifdef CONFIG_DEBUG_STACK_USAGE
     void *ptr2;
 #endif
-    size_t pagesz = qemu_real_host_page_size;
+    size_t pagesz = qemu_real_host_page_size();
 #ifdef _SC_THREAD_STACK_MIN
     /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
     long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
@@ -829,7 +829,7 @@ void qemu_free_stack(void *stack, size_t sz)
     unsigned int usage;
     void *ptr;
 
-    for (ptr = stack + qemu_real_host_page_size; ptr < stack + sz;
+    for (ptr = stack + qemu_real_host_page_size(); ptr < stack + sz;
          ptr += sizeof(uint32_t)) {
         if (*(uint32_t *)ptr != 0xdeadbeaf) {
             break;
@@ -927,10 +927,10 @@ size_t qemu_get_host_physmem(void)
 #ifdef _SC_PHYS_PAGES
     long pages = sysconf(_SC_PHYS_PAGES);
     if (pages > 0) {
-        if (pages > SIZE_MAX / qemu_real_host_page_size) {
+        if (pages > SIZE_MAX / qemu_real_host_page_size()) {
             return SIZE_MAX;
         } else {
-            return pages * qemu_real_host_page_size;
+            return pages * qemu_real_host_page_size();
         }
     }
 #endif

util/oslib-win32.c

@@ -319,7 +319,7 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
                      Error **errp)
 {
     int i;
-    size_t pagesize = qemu_real_host_page_size;
+    size_t pagesize = qemu_real_host_page_size();
 
     memory = (memory + pagesize - 1) & -pagesize;
     for (i = 0; i < memory / pagesize; i++) {

util/pagesize.c

@@ -1,18 +0,0 @@
-/*
- * pagesize.c - query the host about its page size
- *
- * Copyright (C) 2017, Emilio G. Cota <cota@braap.org>
- * License: GNU GPL, version 2 or later.
- *   See the COPYING file in the top-level directory.
- */
-
-#include "qemu/osdep.h"
-
-uintptr_t qemu_real_host_page_size;
-intptr_t qemu_real_host_page_mask;
-
-static void __attribute__((constructor)) init_real_host_page_size(void)
-{
-    qemu_real_host_page_size = getpagesize();
-    qemu_real_host_page_mask = -(intptr_t)qemu_real_host_page_size;
-}

util/vfio-helpers.c

@@ -163,7 +163,7 @@ void *qemu_vfio_pci_map_bar(QEMUVFIOState *s, int index,
                             Error **errp)
 {
     void *p;
-    assert(QEMU_IS_ALIGNED(offset, qemu_real_host_page_size));
+    assert(QEMU_IS_ALIGNED(offset, qemu_real_host_page_size()));
     assert_bar_index_valid(s, index);
     p = mmap(NULL, MIN(size, s->bar_region_info[index].size - offset),
              prot, MAP_SHARED,
@@ -591,9 +591,9 @@ static IOVAMapping *qemu_vfio_add_mapping(QEMUVFIOState *s,
     IOVAMapping m = {.host = host, .size = size, .iova = iova};
     IOVAMapping *insert;
 
-    assert(QEMU_IS_ALIGNED(size, qemu_real_host_page_size));
-    assert(QEMU_IS_ALIGNED(s->low_water_mark, qemu_real_host_page_size));
-    assert(QEMU_IS_ALIGNED(s->high_water_mark, qemu_real_host_page_size));
+    assert(QEMU_IS_ALIGNED(size, qemu_real_host_page_size()));
+    assert(QEMU_IS_ALIGNED(s->low_water_mark, qemu_real_host_page_size()));
+    assert(QEMU_IS_ALIGNED(s->high_water_mark, qemu_real_host_page_size()));
     trace_qemu_vfio_new_mapping(s, host, size, index, iova);
 
     assert(index >= 0);
@@ -644,7 +644,7 @@ static void qemu_vfio_undo_mapping(QEMUVFIOState *s, IOVAMapping *mapping,
 
     index = mapping - s->mappings;
     assert(mapping->size > 0);
-    assert(QEMU_IS_ALIGNED(mapping->size, qemu_real_host_page_size));
+    assert(QEMU_IS_ALIGNED(mapping->size, qemu_real_host_page_size()));
     assert(index >= 0 && index < s->nr_mappings);
     if (ioctl(s->container, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
         error_setg_errno(errp, errno, "VFIO_UNMAP_DMA failed");
@@ -752,8 +752,8 @@ int qemu_vfio_dma_map(QEMUVFIOState *s, void *host, size_t size,
     IOVAMapping *mapping;
     uint64_t iova0;
 
-    assert(QEMU_PTR_IS_ALIGNED(host, qemu_real_host_page_size));
-    assert(QEMU_IS_ALIGNED(size, qemu_real_host_page_size));
+    assert(QEMU_PTR_IS_ALIGNED(host, qemu_real_host_page_size()));
+    assert(QEMU_IS_ALIGNED(size, qemu_real_host_page_size()));
     trace_qemu_vfio_dma_map(s, host, size, temporary, iova);
     QEMU_LOCK_GUARD(&s->lock);
     mapping = qemu_vfio_find_mapping(s, host, &index);