The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From bf1e15a82e3b74ee86bb119d6038b41e1ed2b319 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini pbonzini@redhat.com Date: Tue, 20 Apr 2021 04:13:03 -0400 Subject: [PATCH] KVM: selftests: Always run vCPU thread with blocked SIG_IPI
The main thread could start to send SIG_IPI at any time, even before signal blocked on vcpu thread. Therefore, start the vcpu thread with the signal blocked.
Without this patch, on very busy cores the dirty_log_test could fail directly on receiving a SIGUSR1 without a handler (when vcpu runs far slower than main).
Reported-by: Peter Xu peterx@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c index ffa4e2791926..81edbd23d371 100644 --- a/tools/testing/selftests/kvm/dirty_log_test.c +++ b/tools/testing/selftests/kvm/dirty_log_test.c @@ -527,9 +527,8 @@ static void *vcpu_worker(void *data) */ sigmask->len = 8; pthread_sigmask(0, NULL, sigset); + sigdelset(sigset, SIG_IPI); vcpu_ioctl(vm, VCPU_ID, KVM_SET_SIGNAL_MASK, sigmask); - sigaddset(sigset, SIG_IPI); - pthread_sigmask(SIG_BLOCK, sigset, NULL);
sigemptyset(sigset); sigaddset(sigset, SIG_IPI); @@ -858,6 +857,7 @@ int main(int argc, char *argv[]) .interval = TEST_HOST_LOOP_INTERVAL, }; int opt, i; + sigset_t sigset;
sem_init(&sem_vcpu_stop, 0, 0); sem_init(&sem_vcpu_cont, 0, 0); @@ -916,6 +916,11 @@ int main(int argc, char *argv[])
srandom(time(0));
+ /* Ensure that vCPU threads start with SIG_IPI blocked. */ + sigemptyset(&sigset); + sigaddset(&sigset, SIG_IPI); + pthread_sigmask(SIG_BLOCK, &sigset, NULL); + if (host_log_mode_option == LOG_MODE_ALL) { /* Run each log mode */ for (i = 0; i < LOG_MODE_NUM; i++) {