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KVM: SVM: unconditionally wake up VCPU on IOMMU interrupt

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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>
This commit is contained in:
Paolo Bonzini 2017-10-10 12:51:56 +02:00
parent c1bd743e54
commit 1cf53587c0
1 changed files with 1 additions and 4 deletions
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arch/x86/kvm/svm.c
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@ -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;