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Wed, 30 Sep 2026 14:18:35 -0700 (PDT) Date: Wed, 30 Sep 2026 21:18:33 +0000 In-Reply-To: <20260930211834.2773546-1-coltonlewis@google.com> Mime-Version: 1.0 References: <20260930211834.2773546-1-coltonlewis@google.com> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog Message-ID: <20260930211834.2773546-2-coltonlewis@google.com> Subject: [PATCH v2 1/2] KVM: arm64: Handle ID_AA64DFR0_EL1.PMUVer == NI in __kvm_pmu_event_mask() From: Colton Lewis To: kvmarm@lists.linux.dev Cc: maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, pbonzini@redhat.com, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Colton Lewis Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260930_141838_196298_3C61BF1A X-CRM114-Status: GOOD ( 12.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org When userspace initializes a vCPU with KVM_ARM_VCPU_PMU_V3 but sets ID_AA64DFR0_EL1.PMUVer to NI (0) or IMP_DEF (0xf, which is sanitized to NI), resetting the vCPU invokes reset_pmevtyper() and calls kvm_pmu_evtyper_mask(). Because __kvm_pmu_event_mask() does not handle ID_AA64DFR0_EL1_PMUVer_NI, it triggers a WARN_ONCE("Unknown PMU version 0"). Explicitly handle ID_AA64DFR0_EL1_PMUVer_NI in __kvm_pmu_event_mask() by returning an event mask of 0, and drop the redundant kvm_vcpu_has_pmu() check in reset_pmevtyper(). Fixes: bc512d6a9b92 ("KVM: arm64: Make PMEVTYPER_EL0.NSH RES0 if EL2 isn't advertised") Suggested-by: Oliver Upton Assisted-by: LLM Signed-off-by: Colton Lewis --- arch/arm64/kvm/pmu-emul.c | 5 ++++- arch/arm64/kvm/sys_regs.c | 4 ---- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 5b1af7e2176fa..e2b28dbc0451b 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -50,8 +50,11 @@ static u32 __kvm_pmu_event_mask(unsigned int pmuver) case ID_AA64DFR0_EL1_PMUVer_V3P5: case ID_AA64DFR0_EL1_PMUVer_V3P7: return GENMASK(15, 0); - default: /* Shouldn't be here, just for sanity */ + default: + /* Shouldn't be here, just for sanity */ WARN_ONCE(1, "Unknown PMU version %d\n", pmuver); + fallthrough; + case ID_AA64DFR0_EL1_PMUVer_NI: return 0; } } diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index a2f4e769a4282..e4ad9c171c7ca 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1059,10 +1059,6 @@ static u64 reset_pmevcntr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) static u64 reset_pmevtyper(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) { - /* This thing will UNDEF, who cares about the reset value? */ - if (!kvm_vcpu_has_pmu(vcpu)) - return 0; - reset_unknown(vcpu, r); __vcpu_rmw_sys_reg(vcpu, r->reg, &=, kvm_pmu_evtyper_mask(vcpu->kvm)); -- 2.56.0.rc1.315.gc6ed9934b7-goog