[PATCH] kvm: svm: Introduce GA Log tracepoint for AVIC

[PATCH] kvm: svm: Introduce GA Log tracepoint for AVIC

[Suravee Suthikulpanit]

GA Log tracepoint is useful when debugging AVIC performance
issue as it can be used with perf to count the number of times
IOMMU AVIC injects interrupts through the slow-path instead of
directly inject interrupts to the target vcpu.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 arch/x86/kvm/svm.c   |  1 +
 arch/x86/kvm/trace.h | 18 ++++++++++++++++++
 arch/x86/kvm/x86.c   |  1 +
 3 files changed, 20 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 24c0b2b..504f2cb 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1208,6 +1208,7 @@ static int avic_ga_log_notifier(u32 ga_tag)
 	u32 vcpu_id = AVIC_GATAG_TO_VCPUID(ga_tag);
 
 	pr_debug("SVM: %s: vm_id=%#x, vcpu_id=%#x\n", __func__, vm_id, vcpu_id);
+	trace_kvm_avic_ga_log(vm_id, vcpu_id);
 
 	spin_lock_irqsave(&svm_vm_data_hash_lock, flags);
 	hash_for_each_possible(svm_vm_data_hash, kvm_svm, hnode, vm_id) {
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index f194dd0..023de6c 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1367,6 +1367,24 @@
 		  __entry->vec)
 );
 
+TRACE_EVENT(kvm_avic_ga_log,
+	    TP_PROTO(u32 vmid, u32 vcpuid),
+	    TP_ARGS(vmid, vcpuid),
+
+	TP_STRUCT__entry(
+		__field(u32, vmid)
+		__field(u32, vcpuid)
+	),
+
+	TP_fast_assign(
+		__entry->vmid = vmid;
+		__entry->vcpuid = vcpuid;
+	),
+
+	TP_printk("vmid=%u, vcpuid=%u",
+		  __entry->vmid, __entry->vcpuid)
+);
+
 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 5de2006..ef38b82 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10514,4 +10514,5 @@ u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu)
 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_apicv_update_request);
-- 
1.8.3.1

Re: [PATCH] kvm: svm: Introduce GA Log tracepoint for AVIC

[Paolo Bonzini]

On 12/03/20 11:39, Suravee Suthikulpanit wrote:
> GA Log tracepoint is useful when debugging AVIC performance
> issue as it can be used with perf to count the number of times
> IOMMU AVIC injects interrupts through the slow-path instead of
> directly inject interrupts to the target vcpu.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>  arch/x86/kvm/svm.c   |  1 +
>  arch/x86/kvm/trace.h | 18 ++++++++++++++++++
>  arch/x86/kvm/x86.c   |  1 +
>  3 files changed, 20 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 24c0b2b..504f2cb 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1208,6 +1208,7 @@ static int avic_ga_log_notifier(u32 ga_tag)
>  	u32 vcpu_id = AVIC_GATAG_TO_VCPUID(ga_tag);
>  
>  	pr_debug("SVM: %s: vm_id=%#x, vcpu_id=%#x\n", __func__, vm_id, vcpu_id);
> +	trace_kvm_avic_ga_log(vm_id, vcpu_id);
>  
>  	spin_lock_irqsave(&svm_vm_data_hash_lock, flags);
>  	hash_for_each_possible(svm_vm_data_hash, kvm_svm, hnode, vm_id) {
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index f194dd0..023de6c 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -1367,6 +1367,24 @@
>  		  __entry->vec)
>  );
>  
> +TRACE_EVENT(kvm_avic_ga_log,
> +	    TP_PROTO(u32 vmid, u32 vcpuid),
> +	    TP_ARGS(vmid, vcpuid),
> +
> +	TP_STRUCT__entry(
> +		__field(u32, vmid)
> +		__field(u32, vcpuid)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->vmid = vmid;
> +		__entry->vcpuid = vcpuid;
> +	),
> +
> +	TP_printk("vmid=%u, vcpuid=%u",
> +		  __entry->vmid, __entry->vcpuid)
> +);
> +
>  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 5de2006..ef38b82 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10514,4 +10514,5 @@ u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu)
>  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_apicv_update_request);
> 

Queued, thanks.

Paolo