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[104.155.91.135]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a67f932bf5sm1108584a12.14.2026.09.02.06.30.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Sep 2026 06:30:51 -0700 (PDT) Date: Wed, 2 Sep 2026 14:30:48 +0100 From: Vincent Donnefort To: Fuad Tabba Cc: Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Quentin Perret , Fuad Tabba Subject: Re: [PATCH 03/17] KVM: arm64: Reject the PVTIME vCPU attribute for protected VMs Message-ID: References: <20260831163421.272420-1-fuad.tabba@linux.dev> <20260831163421.272420-4-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260831163421.272420-4-fuad.tabba@linux.dev> On Mon, Aug 31, 2026 at 05:34:07PM +0100, Fuad Tabba wrote: > pKVM currently does not support steal time for protected guests: > KVM_CAP_STEAL_TIME reports 0 for them. The host still accepts the > KVM_ARM_VCPU_PVTIME_CTRL attribute, whose IPA would point > kvm_update_stolen_time() at the guest's private memory on every vCPU > load. Return -EPERM for the attribute group instead. > > Signed-off-by: Fuad Tabba > --- > arch/arm64/kvm/guest.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > index b01d6622b8720..23f725e2cf745 100644 > --- a/arch/arm64/kvm/guest.c > +++ b/arch/arm64/kvm/guest.c > @@ -916,6 +916,10 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, > ret = kvm_arm_timer_set_attr(vcpu, attr); > break; > case KVM_ARM_VCPU_PVTIME_CTRL: > + /* Steal time is not offered to protected guests. */ > + if (kvm_vm_is_protected(vcpu->kvm)) > + return -EPERM; > + nit: We have vcpu_is_protected() Also, would that make more sense to put that check in kvm_arm_pvtime_supported()? > ret = kvm_arm_pvtime_set_attr(vcpu, attr); > break; > default: > @@ -939,6 +943,9 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu, > ret = kvm_arm_timer_get_attr(vcpu, attr); > break; > case KVM_ARM_VCPU_PVTIME_CTRL: > + if (kvm_vm_is_protected(vcpu->kvm)) > + return -EPERM; > + > ret = kvm_arm_pvtime_get_attr(vcpu, attr); > break; > default: > @@ -962,6 +969,9 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu, > ret = kvm_arm_timer_has_attr(vcpu, attr); > break; > case KVM_ARM_VCPU_PVTIME_CTRL: > + if (kvm_vm_is_protected(vcpu->kvm)) > + return -EPERM; > + > ret = kvm_arm_pvtime_has_attr(vcpu, attr); > break; > default: > -- > 2.39.5 > -- Vincent