1 files changed, 10 insertions, 6 deletions

diff --git a/arch/x86/kvm/timer.c b/arch/x86/kvm/timer.c
index 85cc743a8203..1baed414b57a 100644
--- a/arch/x86/kvm/timer.c
+++ b/arch/x86/kvm/timer.c
@@ -9,12 +9,16 @@ static int __kvm_timer_fn(struct kvm_vcpu *vcpu, struct kvm_timer *ktimer)
         int restart_timer = 0;
         wait_queue_head_t *q = &vcpu->wq;
 
-        /* FIXME: this code should not know anything about vcpus */
-        if (!atomic_inc_and_test(&ktimer->pending))
-                set_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests);
-
-        if (!ktimer->reinject)
-                atomic_set(&ktimer->pending, 1);
+        /*
+         * There is a race window between reading and incrementing, but we do
+         * not care about potentially loosing timer events in the !reinject
+         * case anyway.
+         */
+        if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
+                /* FIXME: this code should not know anything about vcpus */
+                if (!atomic_inc_and_test(&ktimer->pending))
+                        set_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests);
+        }
 
         if (waitqueue_active(q))
                 wake_up_interruptible(q);