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SubjectRe: [PATCH] svm/avic: Do not send AVIC doorbell to self
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On 03/05/19 15:38, Suthikulpanit, Suravee wrote:
> 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>
> ---
> arch/x86/kvm/svm.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 122788f..4bbf6fc 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5283,10 +5283,13 @@ 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);
> }
>
>

Queued, thanks.

Paolo

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