aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorIgnacio Alvarado <ikalvarado@google.com>2016-11-04 12:15:55 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-11-26 09:54:52 +0100
commitd4a774fdb92f37da91ebd827c3e507b542ab29b1 (patch)
tree88c703c5df493bc51a972c4051b51669b6bfb7a4
parentb689e86c9a8f81aa80f2ab8a4d5a4635f870af4b (diff)
downloadlinux-linaro-stable-d4a774fdb92f37da91ebd827c3e507b542ab29b1.tar.gz
KVM: Disable irq while unregistering user notifier
commit 1650b4ebc99da4c137bfbfc531be4a2405f951dd upstream. 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@google.com> Fixes: 18863bdd60f8 ("KVM: x86 shared msr infrastructure") Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/x86.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2a04b5fa28c2..7429d481a311 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -199,7 +199,18 @@ 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) {
+ locals->registered = false;
+ user_return_notifier_unregister(urn);
+ }
+ local_irq_restore(flags);
for (slot = 0; slot < shared_msrs_global.nr; ++slot) {
values = &locals->values[slot];
if (values->host != values->curr) {
@@ -207,8 +218,6 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
values->curr = values->host;
}
}
- locals->registered = false;
- user_return_notifier_unregister(urn);
}
static void shared_msr_update(unsigned slot, u32 msr)