* [PATCH v2 1/2] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status [not found] <20241120005230.2335682-1-oliver.upton@linux.dev> @ 2024-11-20 0:52 ` Oliver Upton 2024-11-20 8:18 ` Marc Zyngier 0 siblings, 1 reply; 2+ messages in thread From: Oliver Upton @ 2024-11-20 0:52 UTC (permalink / raw) To: kvmarm Cc: Marc Zyngier, Joey Gouly, Suzuki K Poulose, Zenghui Yu, Mingwei Zhang, Colton Lewis, Raghavendra Rao Ananta, stable, Oliver Upton From: Raghavendra Rao Ananta <rananta@google.com> DDI0487K D13.1.1 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 ] Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- 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 8ad62284fa23..3855cc9d0ca5 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -381,7 +381,6 @@ 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); } -- 2.39.5 ^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2 1/2] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-11-20 0:52 ` [PATCH v2 1/2] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status Oliver Upton @ 2024-11-20 8:18 ` Marc Zyngier 0 siblings, 0 replies; 2+ messages in thread From: Marc Zyngier @ 2024-11-20 8:18 UTC (permalink / raw) To: Oliver Upton Cc: kvmarm, Joey Gouly, Suzuki K Poulose, Zenghui Yu, Mingwei Zhang, Colton Lewis, Raghavendra Rao Ananta, stable On Wed, 20 Nov 2024 00:52:29 +0000, Oliver Upton <oliver.upton@linux.dev> wrote: > > From: Raghavendra Rao Ananta <rananta@google.com> > > DDI0487K D13.1.1 describes the PMU overflow condition, which evaluates nit: DDI0487K.a, and D13.3.1. > 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 ] > Signed-off-by: Oliver Upton <oliver.upton@linux.dev> > --- > 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 8ad62284fa23..3855cc9d0ca5 100644 > --- a/arch/arm64/kvm/pmu-emul.c > +++ b/arch/arm64/kvm/pmu-emul.c > @@ -381,7 +381,6 @@ 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); > } > Reviewed-by: Marc Zyngier <maz@kernel.org> M. -- Without deviation from the norm, progress is not possible. ^ permalink raw reply [flat|nested] 2+ messages in thread
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2024-11-20 0:52 ` [PATCH v2 1/2] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status Oliver Upton
2024-11-20 8:18 ` Marc Zyngier
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