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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a853cafddesm3352206a91.10.2026.10.05.19.24.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Oct 2026 19:24:36 -0700 (PDT) Message-ID: <7f42005b-b840-4a5a-978d-18877bea3481@redhat.com> Date: Tue, 6 Oct 2026 12:24:27 +1000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v22 09/23] KVM: arm64: Prevent unsupported vcpu features for VM types To: Suzuki K Poulose , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com, sudeep.holla@arm.com, jonathan.cameron@oss.qualcomm.com References: <20261005090754.2140522-1-suzuki.poulose@arm.com> <20261005090754.2140522-10-suzuki.poulose@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20261005090754.2140522-10-suzuki.poulose@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/5/26 7:07 PM, Suzuki K Poulose wrote: > Prevent unsupported VCPU features for the protected VCPUs. Realms and pVMs > not support 32bit EL1 or NV yet. pKVM doesn't rely on the host vcpu > features and it clears the unsupported features while hyp_vcpu is > initialised. Block the features early in the vcpu init if we detect > incompatible features. > > Signed-off-by: Suzuki K Poulose > --- > arch/arm64/kvm/arm.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > One nitpick below. In either way: Reviewed-by: Gavin Shan > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index f31d31fa27ad9..9c2ef7ca6a961 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -1668,11 +1668,12 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level, > return -EINVAL; > } > > -static unsigned long system_supported_vcpu_features(void) > +static unsigned long system_supported_vcpu_features(struct kvm_vcpu *vcpu) > { > unsigned long features = KVM_VCPU_VALID_FEATURES; > > - if (!cpus_have_final_cap(ARM64_HAS_32BIT_EL1)) > + if (vcpu_is_protected(vcpu) || > + !cpus_have_final_cap(ARM64_HAS_32BIT_EL1)) > clear_bit(KVM_ARM_VCPU_EL1_32BIT, &features); > > if (!kvm_supports_guest_pmuv3()) { > @@ -1688,7 +1689,8 @@ static unsigned long system_supported_vcpu_features(void) > clear_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, &features); > } > > - if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) > + if (vcpu_is_protected(vcpu) || > + !cpus_have_final_cap(ARM64_HAS_NESTED_VIRT)) > clear_bit(KVM_ARM_VCPU_HAS_EL2, &features); > > return features; > @@ -1708,7 +1710,7 @@ static int kvm_vcpu_init_check_features(struct kvm_vcpu *vcpu, > return -ENOENT; > } > > - if (features & ~system_supported_vcpu_features()) > + if (features & ~system_supported_vcpu_features(vcpu)) > return -EINVAL; > The following check at the beginning of kvm_vcpu_init_check_features() is redundant to the check here. We can drop that in this patch or a preparatory patch. static int kvm_vcpu_init_check_features(...) { /* * This check can be dropped since the same check has been done * by the followup "if (features & ~system_supported_vcpu_features(vcpu))" */ if (features & ~KVM_VCPU_VALID_FEATURES) return -ENOENT; } > /* Thanks, Gavin