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Fri, 02 Oct 2026 14:15:06 +0000 Date: Fri, 02 Oct 2026 15:15:06 +0100 Message-ID: <86pkxs2npx.wl-maz@kernel.org> From: Marc Zyngier To: Suzuki K Poulose , Fuad Tabba Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, 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, gshan@redhat.com, joey.gouly@arm.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 Subject: Re: [PATCH v21 05/23] KVM: arm64: Track the type of VM in kvm_arch In-Reply-To: References: <20261001210703.1597150-1-suzuki.poulose@arm.com> <20261001210703.1597150-6-suzuki.poulose@arm.com> <86se2o2rbs.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: suzuki.poulose@arm.com, tabba@google.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, 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, gshan@redhat.com, joey.gouly@arm.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 X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false 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 On Fri, 02 Oct 2026 14:05:17 +0100, Fuad Tabba wrote: > > Hi Marc, > > On Fri, 02 Oct 2026 13:57:11 +0100, Marc Zyngier wrote: > [...] > > Just to make sure. Is that what you had in mind? > > A diff is worth a thousand words :) Yes, that's it. With that, every > remaining hyp user of vcpu_is_protected() only runs with pKVM, so the > kern_hyp_va() case in the macro can go too. Actually, scratch all of that. The whole thing is written upside down, and makes little sense. I wish I had looked at it more closely... The *_protected__pkvm() shouldn't exist at all, because nVHE is the only context where it matters, and therefore we can specialise the *normal* accessors for the nVHE context (see below). No *_pkvm(), no kern_hyp_va(), nothing at all. I'm also dead against the unprotected_pkvm() stuff, as it looks pointlessly specialised. Specifically, this nugget is making my head spin: + if (!kvm_vm_is_unprotected_pkvm(vcpu->kvm)) return; Honestly, we introduce the flavor stuff to make it easy to match things on a particular VM type in a readable way. So why isn't this reading: if (vcpu->kvm->arch.vm_flavor != VM_PROTECTED_PKVM) return; which makes it pretty explicit. You can gate it with a is_protected_kvm_enabled() if you want, as it was before. M. diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 9e1fa00d96f7c..6b64f9610f3a3 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1519,41 +1519,22 @@ struct kvm *kvm_arch_alloc_vm(void); #define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE -#define kvm_vm_is_protected(kvm) ((kvm)->arch.vm_flavor >= __VM_PROTECTED) -/* - * Accessing vcpu->kvm from nVHE hyp stub is tricky, as we need to convert the - * pointer to the hyp VA. With pKVM, the nVHE code runs with the hyp_vcpu, - * which is populated correctly. - */ -#define vcpu_is_protected(vcpu) \ - ({ \ - struct kvm *__kvm = READ_ONCE((vcpu)->kvm); \ - bool __protected = false; \ - \ - if (__kvm) { \ - if (is_nvhe_hyp_code() && \ - !is_protected_kvm_enabled()) \ - __kvm = kern_hyp_va(__kvm); \ - \ - __protected = kvm_vm_is_protected(__kvm); \ - } \ - __protected; \ - }) - -#define kvm_vm_is_protected_pkvm(kvm) \ +#ifdef __KVM_NVHE_HYPERVISOR__ +#define kvm_vm_is_protected(kvm) \ (is_protected_kvm_enabled() && ((kvm)->arch.vm_flavor == VM_PROTECTED_PKVM)) - /* * Rely on is_protected_kvm_enabled() check in kvm_vm_is_protected_pkvm() to * make sure the vcpu->kvm is always valid VA in the context */ -#define vcpu_is_protected_pkvm(vcpu) \ +#define vcpu_is_protected(vcpu) \ ({ \ struct kvm *__kvm = READ_ONCE((vcpu)->kvm); \ - \ - (__kvm && kvm_vm_is_protected_pkvm(__kvm)); \ + (__kvm && kvm_vm_is_protected(__kvm)); \ }) - +#else +#define kvm_vm_is_protected(kvm) ((kvm)->arch.vm_flavor >= __VM_PROTECTED) +#define vcpu_is_protected(vcpu) kvm_vm_is_protected((vcpu)->kvm) +#endif #define kvm_vm_is_unprotected_pkvm(kvm) \ (is_protected_kvm_enabled() && ((kvm)->arch.vm_flavor == VM_PKVM)) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 0f4e8b71fa85d..9ba86450fe4af 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -2624,7 +2624,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, hva_t hva, reg_end; int ret = 0; - if (kvm_vm_is_protected_pkvm(kvm)) { + if (kvm_vm_is_protected(kvm)) { /* Cannot modify memslots once a pVM has run. */ if (pkvm_hyp_vm_is_created(kvm) && (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) { -- Without deviation from the norm, progress is not possible.