KVM: Disable irq while unregistering user notifier (1650b4eb) · Commits · 戴 / test

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 Fixes: ("KVM: x86 shared msr infrastructure") Reviewed-by:

Paolo Bonzini <pbonzini@redhat.com> Signed-off-by:

Radim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/x86.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -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)

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