From ae1f36f12b2b203c139f28dada4061db7f5d1017 Mon Sep 17 00:00:00 2001 From: Peter Crosthwaite Date: Mon, 23 Mar 2015 03:48:09 -0700 Subject: [PATCH] cpus: Don't kick un-realized cpus. following a464982499b2f637f6699e3d03e0a9d2e0b5288b, it's now possible for there to be attempts to take the BQL before CPUs have been realized in cases where a machine model inits peripherals before the first CPU. BQL lock aquisition kicks the first_cpu, leading to a segfault if this happens pre-realize. Guard the CPU kick routine to perform no action for a CPU that doesn't exist or doesn't have a thread yet. There was a fix to this with commit 6b49809c597331803ea941eadda813e5bb4e8fe2, but the check there misses the case where the CPU has been inited and not realized. Strengthen the check to make sure that the first_cpu has a thread (i.e. it is realized) before allowing the kick. Signed-off-by: Peter Crosthwaite Message-Id: <1427107689-6946-1-git-send-email-peter.crosthwaite@xilinx.com> Signed-off-by: Paolo Bonzini --- cpus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/cpus.c b/cpus.c index 7274f52c73..585b5c19e8 100644 --- a/cpus.c +++ b/cpus.c @@ -1044,7 +1044,7 @@ static bool qemu_in_vcpu_thread(void) void qemu_mutex_lock_iothread(void) { atomic_inc(&iothread_requesting_mutex); - if (!tcg_enabled() || !first_cpu) { + if (!tcg_enabled() || !first_cpu || !first_cpu->thread) { qemu_mutex_lock(&qemu_global_mutex); atomic_dec(&iothread_requesting_mutex); } else {