From 86cf9e154632cb28d749db0ea47946fba8cf3f09 Mon Sep 17 00:00:00 2001 From: Pavel Dovgalyuk Date: Tue, 17 Sep 2019 12:54:06 +0300 Subject: [PATCH] replay: don't synchronize memory operations in replay mode Commit 9458a9a1df1a4c719e24512394d548c1fc7abd22 added synchronization of vCPU and migration operations through calling run_on_cpu operation. However, in replay mode this synchronization is unneeded, because I/O and vCPU threads are already synchronized. This patch disables such synchronization for record/replay mode. Signed-off-by: Pavel Dovgalyuk Signed-off-by: Paolo Bonzini Signed-off-by: Pavel Dovgalyuk --- exec.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/exec.c b/exec.c index 8a0a6613b1..1d6e4d8608 100644 --- a/exec.c +++ b/exec.c @@ -2959,8 +2959,17 @@ static void tcg_log_global_after_sync(MemoryListener *listener) * by pushing the migration thread's memory read after the vCPU thread has * written the memory. */ - cpuas = container_of(listener, CPUAddressSpace, tcg_as_listener); - run_on_cpu(cpuas->cpu, do_nothing, RUN_ON_CPU_NULL); + if (replay_mode == REPLAY_MODE_NONE) { + /* + * VGA can make calls to this function while updating the screen. + * In record/replay mode this causes a deadlock, because + * run_on_cpu waits for rr mutex. Therefore no races are possible + * in this case and no need for making run_on_cpu when + * record/replay is not enabled. + */ + cpuas = container_of(listener, CPUAddressSpace, tcg_as_listener); + run_on_cpu(cpuas->cpu, do_nothing, RUN_ON_CPU_NULL); + } } static void tcg_commit(MemoryListener *listener)