KVM: SVM: unconditionally wake up VCPU on IOMMU interrupt

Checking the mode is unnecessary, and is done without a memory barrier
separating the LAPIC write from the vcpu->mode read; in addition,
kvm_vcpu_wake_up is already doing a check for waiters on the wait queue
that has the same effect.

In practice it's safe because spin_lock has full-barrier semantics on x86,
but don't be too clever.

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0e68f0b..3e4337e 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1034,15 +1034,12 @@ static int avic_ga_log_notifier(u32 ga_tag)
        }
        spin_unlock_irqrestore(&svm_vm_data_hash_lock, flags);
 
-       if (!vcpu)
-               return 0;
-
        /* Note:
         * At this point, the IOMMU should have already set the pending
         * bit in the vAPIC backing page. So, we just need to schedule
         * in the vcpu.
         */
-       if (vcpu->mode == OUTSIDE_GUEST_MODE)
+       if (vcpu)
                kvm_vcpu_wake_up(vcpu);
 
        return 0;