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

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Date:   Thu, 12 Mar 2020 05:39:28 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, joro@...tes.org, jon.grimm@....com,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: [PATCH] kvm: svm: Introduce GA Log tracepoint for AVIC

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@....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