include/qemu/sys_membarrier.h

   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 #ifndef QEMU_SYS_MEMBARRIER_H
  10 #define QEMU_SYS_MEMBARRIER_H
  11
  12 #ifdef CONFIG_MEMBARRIER
  13 /* Only block reordering at the compiler level in the performance-critical
  14  * side.  The slow side forces processor-level ordering on all other cores
  15  * through a system call.
  16  */
  17 extern void smp_mb_global_init(void);
  18 extern void smp_mb_global(void);
  19 #define smp_mb_placeholder()       barrier()
  20 #else
  21 /* Keep it simple, execute a real memory barrier on both sides.  */
  22 static inline void smp_mb_global_init(void) {}
  23 #define smp_mb_global()            smp_mb()
  24 #define smp_mb_placeholder()       smp_mb()
  25 #endif
  26
  27 #endif