From: Marc Zyngier Date: Mon, 17 Feb 2025 10:24:43 +0000 (+0000) Subject: KVM: arm64: Contextualise the handling of PMCR_EL0.P writes X-Git-Tag: v6.16-rc1~129^2~2^2~7^2~4 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=022435334393d56f4d6bc398cf16430067807b0a;p=thirdparty%2Fkernel%2Flinux.git KVM: arm64: Contextualise the handling of PMCR_EL0.P writes Contrary to what the comment says in kvm_pmu_handle_pmcr(), writing PMCR_EL0.P==1 has the following effects: The event counters affected by this field are: * All event counters in the first range. * If any of the following are true, all event counters in the second range: - EL2 is disabled or not implemented in the current Security state. - The PE is executing at EL2 or EL3. where the "first range" represent the counters in the [0..HPMN-1] range, and the "second range" the counters in the [HPMN..MAX] range. It so appears that writing P from EL2 should nuke all counters, and not just the "guest" view. Just do that, and nuke the misleading comment. Reported-by: Joey Gouly Reviewed-by: Oliver Upton Signed-off-by: Marc Zyngier --- diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 2df54508f5aee..2336d9c8bd5e7 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -608,14 +608,12 @@ void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val) kvm_pmu_set_counter_value(vcpu, ARMV8_PMU_CYCLE_IDX, 0); if (val & ARMV8_PMU_PMCR_P) { - /* - * Unlike other PMU sysregs, the controls in PMCR_EL0 always apply - * to the 'guest' range of counters and never the 'hyp' range. - */ unsigned long mask = kvm_pmu_implemented_counter_mask(vcpu) & - ~kvm_pmu_hyp_counter_mask(vcpu) & ~BIT(ARMV8_PMU_CYCLE_IDX); + if (!vcpu_is_el2(vcpu)) + mask &= ~kvm_pmu_hyp_counter_mask(vcpu); + for_each_set_bit(i, &mask, 32) kvm_pmu_set_pmc_value(kvm_vcpu_idx_to_pmc(vcpu, i), 0, true); }