| Message ID | 1478286955-108360-1-git-send-email-ikalvarado@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/11/2016 20:15, Ignacio Alvarado wrote: > 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> Cc: stable@vger.kernel.org Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> > --- > Changelog since v1: > - Move unregistration to the beginning of kvm_on_user_return > > 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 e375235..952e19d 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) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2016-11-17 13:42+0100, Paolo Bonzini: > On 04/11/2016 20:15, Ignacio Alvarado wrote: >> 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> > > Cc: stable@vger.kernel.org > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Applied to kvm/master, thanks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e375235..952e19d 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)
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> --- Changelog since v1: - Move unregistration to the beginning of kvm_on_user_return arch/x86/kvm/x86.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)