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Fri, 02 Oct 2026 15:40:29 +0000 Date: Fri, 02 Oct 2026 16:40:28 +0100 Message-ID: <86mrsw2jrn.wl-maz@kernel.org> From: Marc Zyngier To: Suzuki K Poulose Cc: Fuad Tabba , 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: <10563362-5964-4ef7-b5d7-fe1d67ce4adb@arm.com> References: <20261001210703.1597150-1-suzuki.poulose@arm.com> <20261001210703.1597150-6-suzuki.poulose@arm.com> <86se2o2rbs.wl-maz@kernel.org> <86pkxs2npx.wl-maz@kernel.org> <10563362-5964-4ef7-b5d7-fe1d67ce4adb@arm.com> 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 On Fri, 02 Oct 2026 16:15:07 +0100, Suzuki K Poulose wrote: > > > 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)) { > > We have slightly different handling for Realms. The final code for this > looks like : > > if (kvm_vm_is_protected(kvm)) { > if (new && > new->flags & (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY)) { > return -EPERM; > } > } > > if (kvm_vm_is_protected_pkvm(kvm)) { > /* Cannot modify memslots once a pVM has run. */ > if (pkvm_hyp_vm_is_created(kvm) && > (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) { > return -EPERM; > } > } else if (kvm_realm_is_created(kvm)) { > /* > * Once the Realm is created, we cannot modify any slots that > * could be providing private memory. i.e., guest_memfd backed > * slots. > * TODO: Handle trusted device private memory slots > */ > if (kvm_slot_has_gmem(old) || kvm_slot_has_gmem(new)) > return -EPERM; > } > > > Of course we could invert the checks to detect vm_is_protected_pkvm() This is how I expect this stuff to be written. if (kvm_vm_is_protected(kvm) && new && new->flags & (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY)) return -EPERM; switch (kvm->vm_flavor) { case VM_PROTECTED_PKVM: /* Cannot modify memslots once a pVM has run. */ if (pkvm_hyp_vm_is_created(kvm) && (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) { return -EPERM; break; case VM_CCA: /* * Once the Realm is created, we cannot modify any slots that * could be providing private memory. i.e., guest_memfd backed * slots. * TODO: Handle trusted device private memory slots */ if (kvm_realm_is_created(kvm) && (kvm_slot_has_gmem(old) || kvm_slot_has_gmem(new))) return -EPERM; break; default: break; } We have an enumeration. Make use of it. And the whole "is_created" crap needs to be sorted one way or another. M. -- Without deviation from the norm, progress is not possible.