tcg: synchronize cpu->exit_request and cpu->tcg_exit_req accesses

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/cpu-exec.c b/cpu-exec.c
index 567ae8b..e24c640 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -507,8 +507,12 @@ int cpu_exec(CPUState *cpu)
                          * loop. Whatever requested the exit will also
                          * have set something else (eg exit_request or
                          * interrupt_request) which we will handle
-                         * next time around the loop.
+                         * next time around the loop.  But we need to
+                         * ensure the tcg_exit_req read in generated code
+                         * comes before the next read of cpu->exit_request
+                         * or cpu->interrupt_request.
                          */
+                        smp_rmb();
                         next_tb = 0;
                         break;
                     case TB_EXIT_ICOUNT_EXPIRED: