Function user_notifier_unregister should be called only once for each
registered user notifier.
Function kvm_arch_hardware_disable can be executed from an IPI context
which could cause a race condition with a VCPU returning to user mode
and attempting to unregister the notifier.
Signed-off-by: Ignacio Alvarado <ikalvarado@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e375235..51f87f0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -210,7 +210,15 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
struct kvm_shared_msrs *locals
= container_of(urn, struct kvm_shared_msrs, urn);
struct kvm_shared_msr_values *values;
+ unsigned long flags;
+ /*
+ * Disabling irqs at this point since the following code could be
+ * interrupted and executed through kvm_arch_hardware_disable()
+ */
+ local_irq_save(flags);
+ if (!locals->registered)
+ goto out;
for (slot = 0; slot < shared_msrs_global.nr; ++slot) {
values = &locals->values[slot];
if (values->host != values->curr) {
@@ -220,6 +228,8 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
}
locals->registered = false;
user_return_notifier_unregister(urn);
+out:
+ local_irq_restore(flags);
}
static void shared_msr_update(unsigned slot, u32 msr)
--
2.8.0.rc3.226.g39d4020
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
