util/sys_membarrier.c

   1 /*
   2  * Process-global memory barriers
   3  *
   4  * Copyright (c) 2018 Red Hat, Inc.
   5  *
   6  * Author: Paolo Bonzini <pbonzini@redhat.com>
   7  */
   8
   9 #include "qemu/osdep.h"
  10 #include "qemu/sys_membarrier.h"
  11 #include "qemu/error-report.h"
  12
  13 #ifdef CONFIG_LINUX
  14 #include <linux/membarrier.h>
  15 #include <sys/syscall.h>
  16
  17 static int
  18 membarrier(int cmd, int flags)
  19 {
  20     return syscall(__NR_membarrier, cmd, flags);
  21 }
  22 #endif
  23
  24 void smp_mb_global(void)
  25 {
  26 #if defined CONFIG_WIN32
  27     FlushProcessWriteBuffers();
  28 #elif defined CONFIG_LINUX
  29     membarrier(MEMBARRIER_CMD_SHARED, 0);
  30 #else
  31 #error --enable-membarrier is not supported on this operating system.
  32 #endif
  33 }
  34
  35 void smp_mb_global_init(void)
  36 {
  37 #ifdef CONFIG_LINUX
  38     int ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
  39     if (ret < 0) {
  40         error_report("This QEMU binary requires the membarrier system call.");
  41         error_report("Please upgrade your system to a newer version of Linux");
  42         exit(1);
  43     }
  44     if (!(ret & MEMBARRIER_CMD_SHARED)) {
  45         error_report("This QEMU binary requires MEMBARRIER_CMD_SHARED support.");
  46         error_report("Please upgrade your system to a newer version of Linux");
  47         exit(1);
  48     }
  49 #endif
  50 }