linux-kernel - [PATCH 2/2] KVM: SVM: Introduce trace point for the slow-path of avic_kic_target

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Date:   Thu, 14 Apr 2022 00:11:51 -0500
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
CC:     <pbonzini@...hat.com>, <mlevitsk@...hat.com>, <seanjc@...gle.com>,
        <joro@...tes.org>, <jon.grimm@....com>, <wei.huang2@....com>,
        <terry.bowman@....com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
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 <suravee.suthikulpanit@....com>
---
 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