kvm: svm/avic: Do not send AVIC doorbell to self

AVIC doorbell is used to notify a running vCPU that interrupts
has been injected into the vCPU AVIC backing page. Current logic
checks only if a VCPU is running before sending a doorbell.
However, the doorbell is not necessary if the destination
CPU is itself.

Add logic to check currently running CPU before sending doorbell.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a7ea34b..c56f40d 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5163,10 +5163,13 @@ static void svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec)
        kvm_lapic_set_irr(vec, vcpu->arch.apic);
        smp_mb__after_atomic();
 
-       if (avic_vcpu_is_running(vcpu))
-               wrmsrl(SVM_AVIC_DOORBELL,
-                      kvm_cpu_get_apicid(vcpu->cpu));
-       else
+       if (avic_vcpu_is_running(vcpu)) {
+               int cpuid = vcpu->cpu;
+
+               if (cpuid != get_cpu())
+                       wrmsrl(SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpuid));
+               put_cpu();
+       } else
                kvm_vcpu_wake_up(vcpu);
 }