linux-kernel - [PATCH 2/4] KVM: x86/pmu: Simplify intel_hw_event

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Message-ID: <20230607010206.1425277-3-seanjc@google.com>
Date:   Tue,  6 Jun 2023 18:02:04 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Aaron Lewis <aaronlewis@...gle.com>,
        Like Xu <like.xu.linux@...il.com>
Subject: [PATCH 2/4] KVM: x86/pmu: Simplify intel_hw_event_available()

Walk only the "real", i.e. non-pseudo, architectural events when checking
if a hardware event is available, i.e. isn't disabled by guest CPUID.
Skipping pseudo-arch events in the loop body is unnecessarily convoluted,
especially now that KVM has enums that delineate between real and pseudo
events.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/pmu_intel.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 0050d71c9c01..f281e634af3c 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -122,17 +122,16 @@ static bool intel_hw_event_available(struct kvm_pmc *pmc)
 
 	BUILD_BUG_ON(ARRAY_SIZE(intel_arch_events) != NR_INTEL_ARCH_EVENTS);
 
-	for (i = 0; i < NR_INTEL_ARCH_EVENTS; i++) {
+	/*
+	 * Disallow events reported as unavailable in guest CPUID.  Note, this
+	 * doesn't apply to pseudo-architectural events.
+	 */
+	for (i = 0; i < NR_REAL_INTEL_ARCH_EVENTS; i++) {
 		if (intel_arch_events[i].eventsel != event_select ||
 		    intel_arch_events[i].unit_mask != unit_mask)
 			continue;
 
-		/* disable event that reported as not present by cpuid */
-		if ((i < PSEUDO_ARCH_REFERENCE_CYCLES) &&
-		    !(pmu->available_event_types & (1 << i)))
-			return false;
-
-		break;
+		return pmu->available_event_types & BIT(i);
 	}
 
 	return true;
-- 
2.41.0.162.gfafddb0af9-goog