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 } 51