LXR qemu/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
  17static int
  18membarrier(int cmd, int flags)
  19{
  20    return syscall(__NR_membarrier, cmd, flags);
  21}
  22#endif
  23
  24void 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
  35void 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}
  51