linux-kernel - [PATCH v2 08/16] KVM: arm64: Add tracepoint for failed MMIO guard check

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Date:   Mon,  4 Oct 2021 18:48:41 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     will@...nel.org, qperret@...gle.com, dbrazdil@...gle.com,
        Steven Price <steven.price@....com>,
        Andrew Jones <drjones@...hat.com>,
        Fuad Tabba <tabba@...gle.com>,
        Srivatsa Vaddagiri <vatsa@...eaurora.org>,
        Shanker R Donthineni <sdonthineni@...dia.com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        kernel-team@...roid.com
Subject: [PATCH v2 08/16] KVM: arm64: Add tracepoint for failed MMIO guard check

In order to make debugging easier, expose a new trace point
that triggers when a MMIO check fails.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 arch/arm64/kvm/mmu.c       |  4 +++-
 arch/arm64/kvm/trace_arm.h | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 2470a55ca675..8c38d856533f 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1275,8 +1275,10 @@ bool kvm_check_ioguard_page(struct kvm_vcpu *vcpu, gpa_t ipa)
 	ret = __check_ioguard_page(vcpu, ipa & PAGE_MASK);
 	spin_unlock(&vcpu->kvm->mmu_lock);
 
-	if (!ret)
+	if (!ret) {
+		trace_kvm_failed_mmio_check(*vcpu_pc(vcpu), ipa);
 		kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
+	}
 
 	return ret;
 }
diff --git a/arch/arm64/kvm/trace_arm.h b/arch/arm64/kvm/trace_arm.h
index 33e4e7dd2719..e40cfeb251ad 100644
--- a/arch/arm64/kvm/trace_arm.h
+++ b/arch/arm64/kvm/trace_arm.h
@@ -89,6 +89,23 @@ TRACE_EVENT(kvm_access_fault,
 	TP_printk("IPA: %lx", __entry->ipa)
 );
 
+TRACE_EVENT(kvm_failed_mmio_check,
+	TP_PROTO(unsigned long vcpu_pc, unsigned long ipa),
+	TP_ARGS(vcpu_pc, ipa),
+
+	TP_STRUCT__entry(
+		__field(	unsigned long,	vcpu_pc		)
+		__field(	unsigned long,	ipa		)
+	),
+
+	TP_fast_assign(
+		__entry->vcpu_pc	= vcpu_pc;
+		__entry->ipa		= ipa;
+	),
+
+	TP_printk("PC: %lx IPA: %lx", __entry->vcpu_pc, __entry->ipa)
+);
+
 TRACE_EVENT(kvm_irq_line,
 	TP_PROTO(unsigned int type, int vcpu_idx, int irq_num, int level),
 	TP_ARGS(type, vcpu_idx, irq_num, level),
-- 
2.30.2