* [PATCH] svm/avic: Do not send AVIC doorbell to self
@ 2019-05-03 13:38 Suthikulpanit, Suravee
2019-05-07 13:16 ` Graf, Alexander
2019-05-20 12:56 ` Paolo Bonzini
0 siblings, 2 replies; 4+ messages in thread
From: Suthikulpanit, Suravee @ 2019-05-03 13:38 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: pbonzini, rkrcmar, joro, Suthikulpanit, Suravee
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);
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] svm/avic: Do not send AVIC doorbell to self
2019-05-03 13:38 [PATCH] svm/avic: Do not send AVIC doorbell to self Suthikulpanit, Suravee
@ 2019-05-07 13:16 ` Graf, Alexander
2019-05-14 15:52 ` Suthikulpanit, Suravee
2019-05-20 12:56 ` Paolo Bonzini
1 sibling, 1 reply; 4+ messages in thread
From: Graf, Alexander @ 2019-05-07 13:16 UTC (permalink / raw)
To: Suthikulpanit, Suravee, linux-kernel, kvm; +Cc: pbonzini, rkrcmar, joro
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>
Reviewed-by: Alexander Graf <graf@amazon.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())
Tiny nitpick: What would keep you from checking vcpu->cpu directly here?
Alex
> + wrmsrl(SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpuid));
> + put_cpu();
> + } else
> kvm_vcpu_wake_up(vcpu);
> }
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] svm/avic: Do not send AVIC doorbell to self
2019-05-07 13:16 ` Graf, Alexander
@ 2019-05-14 15:52 ` Suthikulpanit, Suravee
0 siblings, 0 replies; 4+ messages in thread
From: Suthikulpanit, Suravee @ 2019-05-14 15:52 UTC (permalink / raw)
To: Graf, Alexander, linux-kernel, kvm; +Cc: pbonzini, rkrcmar, joro
Alex,
On 5/7/2019 8:16 AM, Graf, Alexander wrote:
> [CAUTION: External Email]
>
> 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>
>
> Reviewed-by: Alexander Graf <graf@amazon.com>
Thanks.
>> ---
>> 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())
>
> Tiny nitpick: What would keep you from checking vcpu->cpu directly here?
Nothing. Just coding style.
Thanks,
Suravee
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] svm/avic: Do not send AVIC doorbell to self
2019-05-03 13:38 [PATCH] svm/avic: Do not send AVIC doorbell to self Suthikulpanit, Suravee
2019-05-07 13:16 ` Graf, Alexander
@ 2019-05-20 12:56 ` Paolo Bonzini
1 sibling, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2019-05-20 12:56 UTC (permalink / raw)
To: Suthikulpanit, Suravee, linux-kernel, kvm; +Cc: rkrcmar, joro
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
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-05-20 12:56 UTC | newest]
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2019-05-03 13:38 [PATCH] svm/avic: Do not send AVIC doorbell to self Suthikulpanit, Suravee
2019-05-07 13:16 ` Graf, Alexander
2019-05-14 15:52 ` Suthikulpanit, Suravee
2019-05-20 12:56 ` Paolo Bonzini
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