linux-kernel - [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

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Message-ID: <20241119205841.268247-1-rananta@google.com>
Date: Tue, 19 Nov 2024 20:58:41 +0000
From: Raghavendra Rao Ananta <rananta@...gle.com>
To: Oliver Upton <oliver.upton@...ux.dev>, Marc Zyngier <maz@...nel.org>
Cc: Raghavendra Rao Anata <rananta@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

kvm_pmu_overflow_status() currently checks if the PMCs are enabled for
evaluating the PMU overflow condition. However, ARM ARM D13.1.1 states
that a global enable control (PMCR.E), PMOVSSET<n>, and PMINTENSET<n>
are sufficent to consider that the overflow condition is met. Hence,
ignore the check for PMCNTENSET<n>.

The bug was discovered while running the SBSA PMU test, which only sets
PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.

Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
---
 arch/arm64/kvm/pmu-emul.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index ac36c438b8c1..3940fe893783 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -342,7 +342,6 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
 
 	if ((kvm_vcpu_read_pmcr(vcpu) & ARMV8_PMU_PMCR_E)) {
 		reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
-		reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
 		reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
 	}
 

base-commit: adc218676eef25575469234709c2d87185ca223a
-- 
2.47.0.338.g60cca15819-goog