1 files changed, 34 insertions, 3 deletions

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 9829149e4b..9efdc74bba 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -35,6 +35,7 @@
 #include "sysemu/sysemu.h"
 #include "trace.h"
 #include "qapi/error.h"
+#include "qemu/error-report.h"
 #include "qemu/sockets.h"
 #include "qemu/thread.h"
 #include <libgen.h>
@@ -95,6 +96,7 @@ typedef struct MemsetThread MemsetThread;
 
 /* used by sigbus_handler() */
 static MemsetContext *sigbus_memset_context;
+struct sigaction sigbus_oldact;
 static QemuMutex sigbus_mutex;
 
 static QemuMutex page_mutex;
@@ -446,7 +448,11 @@ const char *qemu_get_exec_dir(void)
     return exec_dir;
 }
 
+#ifdef CONFIG_LINUX
+static void sigbus_handler(int signal, siginfo_t *siginfo, void *ctx)
+#else /* CONFIG_LINUX */
 static void sigbus_handler(int signal)
+#endif /* CONFIG_LINUX */
 {
     int i;
 
@@ -459,6 +465,26 @@ static void sigbus_handler(int signal)
             }
         }
     }
+
+#ifdef CONFIG_LINUX
+    /*
+     * We assume that the MCE SIGBUS handler could have been registered. We
+     * should never receive BUS_MCEERR_AO on any of our threads, but only on
+     * the main thread registered for PR_MCE_KILL_EARLY. Further, we should not
+     * receive BUS_MCEERR_AR triggered by action of other threads on one of
+     * our threads. So, no need to check for unrelated SIGBUS when seeing one
+     * for our threads.
+     *
+     * We will forward to the MCE handler, which will either handle the SIGBUS
+     * or reinstall the default SIGBUS handler and reraise the SIGBUS. The
+     * default SIGBUS handler will crash the process, so we don't care.
+     */
+    if (sigbus_oldact.sa_flags & SA_SIGINFO) {
+        sigbus_oldact.sa_sigaction(signal, siginfo, ctx);
+        return;
+    }
+#endif /* CONFIG_LINUX */
+    warn_report("os_mem_prealloc: unrelated SIGBUS detected and ignored");
 }
 
 static void *do_touch_pages(void *arg)
@@ -628,10 +654,10 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
 {
     static gsize initialized;
     int ret;
-    struct sigaction act, oldact;
     size_t hpagesize = qemu_fd_getpagesize(fd);
     size_t numpages = DIV_ROUND_UP(memory, hpagesize);
     bool use_madv_populate_write;
+    struct sigaction act;
 
     /*
      * Sense on every invocation, as MADV_POPULATE_WRITE cannot be used for
@@ -647,10 +673,15 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
 
         qemu_mutex_lock(&sigbus_mutex);
         memset(&act, 0, sizeof(act));
+#ifdef CONFIG_LINUX
+        act.sa_sigaction = &sigbus_handler;
+        act.sa_flags = SA_SIGINFO;
+#else /* CONFIG_LINUX */
         act.sa_handler = &sigbus_handler;
         act.sa_flags = 0;
+#endif /* CONFIG_LINUX */
 
-        ret = sigaction(SIGBUS, &act, &oldact);
+        ret = sigaction(SIGBUS, &act, &sigbus_oldact);
         if (ret) {
             error_setg_errno(errp, errno,
                 "os_mem_prealloc: failed to install signal handler");
@@ -667,7 +698,7 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
     }
 
     if (!use_madv_populate_write) {
-        ret = sigaction(SIGBUS, &oldact, NULL);
+        ret = sigaction(SIGBUS, &sigbus_oldact, NULL);
         if (ret) {
             /* Terminate QEMU since it can't recover from error */
             perror("os_mem_prealloc: failed to reinstall signal handler");