linux-kernel - [PATCH 2/7] KVM: x86/pmu: Fix available_event_types check for REF_CPU

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Message-Id: <20211112095139.21775-3-likexu@tencent.com>
Date:   Fri, 12 Nov 2021 17:51:34 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Like Xu <likexu@...cent.com>
Subject: [PATCH 2/7] KVM: x86/pmu: Fix available_event_types check for REF_CPU_CYCLES event

From: Like Xu <likexu@...cent.com>

For the CPUID 0x0A.EBX bit vector, the [7] event should be the Intel
unrealized architectural performance events "Topdown Slots" instead
of the *kernel* generalized common hardware event "REF_CPU_CYCLES", so
we can skip the cpuid unavaliblity check in the intel_find_arch_event()
for the last REF_CPU_CYCLES event and update the confusing comment.

Fixes: 62079d8a43128 ("KVM: PMU: add proper support for fixed counter 2")
Signed-off-by: Like Xu <likexu@...cent.com>
---
 arch/x86/kvm/vmx/pmu_intel.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index b8e0d21b7c8a..bc6845265362 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -21,7 +21,6 @@
 #define MSR_PMC_FULL_WIDTH_BIT      (MSR_IA32_PMC0 - MSR_IA32_PERFCTR0)
 
 static struct kvm_event_hw_type_mapping intel_arch_events[] = {
-	/* Index must match CPUID 0x0A.EBX bit vector */
 	[0] = { 0x3c, 0x00, PERF_COUNT_HW_CPU_CYCLES },
 	[1] = { 0xc0, 0x00, PERF_COUNT_HW_INSTRUCTIONS },
 	[2] = { 0x3c, 0x01, PERF_COUNT_HW_BUS_CYCLES  },
@@ -29,6 +28,7 @@ static struct kvm_event_hw_type_mapping intel_arch_events[] = {
 	[4] = { 0x2e, 0x41, PERF_COUNT_HW_CACHE_MISSES },
 	[5] = { 0xc4, 0x00, PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
 	[6] = { 0xc5, 0x00, PERF_COUNT_HW_BRANCH_MISSES },
+	/* The above index must match CPUID 0x0A.EBX bit vector */
 	[7] = { 0x00, 0x03, PERF_COUNT_HW_REF_CPU_CYCLES },
 };
 
@@ -75,9 +75,9 @@ static unsigned intel_find_arch_event(struct kvm_pmu *pmu,
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(intel_arch_events); i++)
-		if (intel_arch_events[i].eventsel == event_select
-		    && intel_arch_events[i].unit_mask == unit_mask
-		    && (pmu->available_event_types & (1 << i)))
+		if (intel_arch_events[i].eventsel == event_select &&
+		    intel_arch_events[i].unit_mask == unit_mask &&
+		    ((i > 6) || pmu->available_event_types & (1 << i)))
 			break;
 
 	if (i == ARRAY_SIZE(intel_arch_events))
-- 
2.33.0