2022-05-04 10:14:26

by Suthikulpanit, Suravee

Subject: [PATCH v3 14/14] KVM: SVM: Add AVIC doorbell tracepoint

Add a tracepoint to track number of doorbells being sent
to signal a running vCPU to process IRQ after being injected.

Signed-off-by: Suravee Suthikulpanit <[email protected]>
---
arch/x86/kvm/svm/avic.c | 4 +++-
arch/x86/kvm/trace.h | 18 ++++++++++++++++++
arch/x86/kvm/x86.c | 1 +
3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index a526fbc60bbd..e3343cfc55cd 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -343,8 +343,10 @@ void avic_ring_doorbell(struct kvm_vcpu *vcpu)
*/
int cpu = READ_ONCE(vcpu->cpu);

- if (cpu != get_cpu())
+ if (cpu != get_cpu()) {
wrmsrl(MSR_AMD64_SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpu));
+ trace_kvm_avic_doorbell(vcpu->vcpu_id, kvm_cpu_get_apicid(cpu));
+ }
put_cpu();
}

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index de4762517569..a47bb0fdea70 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1479,6 +1479,24 @@ TRACE_EVENT(kvm_avic_kick_vcpu_slowpath,
__entry->icrh, __entry->icrl, __entry->index)
);

+TRACE_EVENT(kvm_avic_doorbell,
+ TP_PROTO(u32 vcpuid, u32 apicid),
+ TP_ARGS(vcpuid, apicid),
+
+ TP_STRUCT__entry(
+ __field(u32, vcpuid)
+ __field(u32, apicid)
+ ),
+
+ TP_fast_assign(
+ __entry->vcpuid = vcpuid;
+ __entry->apicid = apicid;
+ ),
+
+ TP_printk("vcpuid=%u, apicid=%u",
+ __entry->vcpuid, __entry->apicid)
+);
+
TRACE_EVENT(kvm_hv_timer_state,
TP_PROTO(unsigned int vcpu_id, unsigned int hv_timer_in_use),
TP_ARGS(vcpu_id, hv_timer_in_use),
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b14e02ea0ff6..69a91f47a509 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13097,6 +13097,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_unaccelerated_access);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_incomplete_ipi);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_ga_log);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_kick_vcpu_slowpath);
+EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_doorbell);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_apicv_accept_irq);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_enter);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_exit);
--
2.25.1

2022-05-05 12:14:02

by Maxim Levitsky

Subject: Re: [PATCH v3 14/14] KVM: SVM: Add AVIC doorbell tracepoint

On Wed, 2022-05-04 at 02:31 -0500, Suravee Suthikulpanit wrote:
> Add a tracepoint to track number of doorbells being sent
> to signal a running vCPU to process IRQ after being injected.
>
> Signed-off-by: Suravee Suthikulpanit <[email protected]>
> ---
> arch/x86/kvm/svm/avic.c | 4 +++-
> arch/x86/kvm/trace.h | 18 ++++++++++++++++++
> arch/x86/kvm/x86.c | 1 +
> 3 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index a526fbc60bbd..e3343cfc55cd 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -343,8 +343,10 @@ void avic_ring_doorbell(struct kvm_vcpu *vcpu)
> */
> int cpu = READ_ONCE(vcpu->cpu);
>
> - if (cpu != get_cpu())
> + if (cpu != get_cpu()) {
> wrmsrl(MSR_AMD64_SVM_AVIC_DOORBELL, kvm_cpu_get_apicid(cpu));
> + trace_kvm_avic_doorbell(vcpu->vcpu_id, kvm_cpu_get_apicid(cpu));
> + }
> put_cpu();
> }
>
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index de4762517569..a47bb0fdea70 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -1479,6 +1479,24 @@ TRACE_EVENT(kvm_avic_kick_vcpu_slowpath,
> __entry->icrh, __entry->icrl, __entry->index)
> );
>
> +TRACE_EVENT(kvm_avic_doorbell,
> + TP_PROTO(u32 vcpuid, u32 apicid),
> + TP_ARGS(vcpuid, apicid),
> +
> + TP_STRUCT__entry(
> + __field(u32, vcpuid)
> + __field(u32, apicid)
> + ),
> +
> + TP_fast_assign(
> + __entry->vcpuid = vcpuid;
> + __entry->apicid = apicid;
> + ),
> +
> + TP_printk("vcpuid=%u, apicid=%u",
> + __entry->vcpuid, __entry->apicid)
> +);
> +
> TRACE_EVENT(kvm_hv_timer_state,
> TP_PROTO(unsigned int vcpu_id, unsigned int hv_timer_in_use),
> TP_ARGS(vcpu_id, hv_timer_in_use),
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b14e02ea0ff6..69a91f47a509 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -13097,6 +13097,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_unaccelerated_access);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_incomplete_ipi);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_ga_log);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_kick_vcpu_slowpath);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_avic_doorbell);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_apicv_accept_irq);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_enter);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_exit);


To be honest we already have the 'kvm_apicv_accept_irq'
which usually results in a doorbell, but no objections
to add this tracepoint.

Reviewed-by: Maxim Levitsky <[email protected]>

Best regards,
Maxim Levitsky