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authorIgnacio Alvarado <ikalvarado@google.com>2016-11-04 12:15:55 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-11-26 09:56:53 +0100
commit1cb9b2489e778b4f0d97a98ef35be00b2498d94d (patch)
tree95e756ad8c3aaa53db6bceaf43e046d0949c4b83
parent23555ca21394c0f5a146c891128bd4edc3e78862 (diff)
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 692f3023b513..2fff65794f46 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -210,7 +210,18 @@ 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) {
@@ -218,8 +229,6 @@ 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)