From: Sean Christopherson <seanjc@google.com>
Date: Wed, 7 Jun 2023 01:02:04 +0000 (-0700)
Subject: KVM: x86/pmu: Simplify intel_hw_event_available()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bc9658999b3e44cbad964fe9fbab5a25bd4f5ed3;p=linux.git

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.

Link: https://lore.kernel.org/r/20230607010206.1425277-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
---

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 1109cbdedcae4..db23697f31415 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -110,17 +110,16 @@ 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;