From 8b6916f4cf7d4aba2d710409d5e2fc66eacbd623 Mon Sep 17 00:00:00 2001
From: Raghavendra Rao Ananta <rananta@google.com>
Date: Tue, 19 Nov 2024 16:52:29 -0800
Subject: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow
status
commit 54bbee190d42166209185d89070c58a343bf514b upstream.
DDI0487K.a D13.3.1 describes the PMU overflow condition, which evaluates
to true if any counter's global enable (PMCR_EL0.E), overflow flag
(PMOVSSET_EL0[n]), and interrupt enable (PMINTENSET_EL1[n]) are all 1.
Of note, this does not require a counter to be enabled
(i.e. PMCNTENSET_EL0[n] = 1) to generate an overflow.
Align kvm_pmu_overflow_status() with the reality of the architecture
and stop using PMCNTENSET_EL0 as part of the overflow condition. The
bug was discovered while running an SBSA PMU test [*], which only sets
PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.
Cc: stable@vger.kernel.org
Fixes: 76d883c4e640 ("arm64: KVM: Add access handler for PMOVSSET and PMOVSCLR register")
Link: https://github.com/ARM-software/sbsa-acs/blob/master/test_pool/pmu/operating_system/test_pmu001.c
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
[ oliver: massaged changelog ]
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241120005230.2335682-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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 ac36c438b8c18..3940fe893783c 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);
}
--
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