From: Ignacio Alvarado <ikalvar...@google.com> 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 <ikalvar...@google.com> Reviewed-by: Paolo Bonzini <pbonz...@redhat.com> Backport of https://patchwork.kernel.org/patch/9413131/ Fixes https://jira.sw.ru/browse/PSBM-55099 Signed-off-by: Evgeny Yakovlev <eyakov...@virtuozzo.com> --- arch/x86/kvm/x86.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ea058a2..4b2754b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -198,7 +198,18 @@ 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) { @@ -206,8 +217,6 @@ 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) -- 1.8.3.1 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel