2022-04-14 14:44:06

by Suthikulpanit, Suravee

Subject: [PATCH 2/2] KVM: SVM: Introduce trace point for the slow-path of avic_kic_target_vcpus

This can help identify potential performance issues when handles
AVIC incomplete IPI due vCPU not running.

Signed-off-by: Suravee Suthikulpanit <[email protected]>
---
arch/x86/kvm/svm/avic.c | 2 ++
arch/x86/kvm/trace.h | 20 ++++++++++++++++++++
arch/x86/kvm/x86.c | 1 +
3 files changed, 23 insertions(+)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 92d8e0de1fb4..e5fb4931a2f1 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -440,6 +440,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
if (!avic_kick_target_vcpus_fast(kvm, source, icrl, icrh, index))
return;

+ trace_kvm_avic_kick_vcpu_slowpath(icrh, icrl, index);
+
/*
* Wake any target vCPUs that are blocking, i.e. waiting for a wake
* event. There's no need to signal doorbells, as hardware has handled
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index e3a24b8f04be..de4762517569 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1459,6 +1459,26 @@ TRACE_EVENT(kvm_avic_ga_log,
__entry->vmid, __entry->vcpuid)
);

+TRACE_EVENT(kvm_avic_kick_vcpu_slowpath,
+ TP_PROTO(u32 icrh, u32 icrl, u32 index),
+ TP_ARGS(icrh, icrl, index),
+
+ TP_STRUCT__entry(
+ __field(u32, icrh)
+ __field(u32, icrl)
+ __field(u32, index)
+ ),
+
+ TP_fast_assign(
+ __entry->icrh = icrh;
+ __entry->icrl = icrl;
+ __entry->index = index;
+ ),
+
+ TP_printk("icrh:icrl=%#08x:%08x, index=%u",
+ __entry->icrh, __entry->icrl, __entry->index)
+);
+
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 d0fac57e9996..c2da6c7516b0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12978,6 +12978,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_pi_irte_update);
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_apicv_accept_irq);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_enter);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_exit);
--
2.25.1

2022-04-18 22:54:56

by Maxim Levitsky

Subject: Re: [PATCH 2/2] KVM: SVM: Introduce trace point for the slow-path of avic_kic_target_vcpus

On Thu, 2022-04-14 at 00:11 -0500, Suravee Suthikulpanit wrote:
> This can help identify potential performance issues when handles
> AVIC incomplete IPI due vCPU not running.
>
> Signed-off-by: Suravee Suthikulpanit <[email protected]>
> ---
> arch/x86/kvm/svm/avic.c | 2 ++
> arch/x86/kvm/trace.h | 20 ++++++++++++++++++++
> arch/x86/kvm/x86.c | 1 +
> 3 files changed, 23 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 92d8e0de1fb4..e5fb4931a2f1 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -440,6 +440,8 @@ static void avic_kick_target_vcpus(struct kvm *kvm, struct kvm_lapic *source,
> if (!avic_kick_target_vcpus_fast(kvm, source, icrl, icrh, index))
> return;
>
> + trace_kvm_avic_kick_vcpu_slowpath(icrh, icrl, index);
> +
> /*
> * Wake any target vCPUs that are blocking, i.e. waiting for a wake
> * event. There's no need to signal doorbells, as hardware has handled
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index e3a24b8f04be..de4762517569 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -1459,6 +1459,26 @@ TRACE_EVENT(kvm_avic_ga_log,
> __entry->vmid, __entry->vcpuid)
> );
>
> +TRACE_EVENT(kvm_avic_kick_vcpu_slowpath,
> + TP_PROTO(u32 icrh, u32 icrl, u32 index),
> + TP_ARGS(icrh, icrl, index),
> +
> + TP_STRUCT__entry(
> + __field(u32, icrh)
> + __field(u32, icrl)
> + __field(u32, index)
> + ),
> +
> + TP_fast_assign(
> + __entry->icrh = icrh;
> + __entry->icrl = icrl;
> + __entry->index = index;
> + ),
> +
> + TP_printk("icrh:icrl=%#08x:%08x, index=%u",
> + __entry->icrh, __entry->icrl, __entry->index)
> +);
> +
> 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 d0fac57e9996..c2da6c7516b0 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12978,6 +12978,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_pi_irte_update);
> 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_apicv_accept_irq);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_enter);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_exit);

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

Best regards,
Maxim Levitsky