From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9E48138D686; Fri, 2 Oct 2026 15:15:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790954115; cv=none; b=jZtToHQb4dRHn7d+IpYu/xOYWX00IqdRCLOCbCpXypz77bGciVAM34Aqoe0izG3+RJOrHoOPRUnsdjdQEDSnys9gLBoxdFcf4Gr66HXxw0IznnVc4OJtP5+dDXEhdFXeYeOxXt/ZX7EpD4wD6genImgF/gTXM/MI7A3MSclDJtU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790954115; c=relaxed/simple; bh=ELvA9eECm9X8xz8cLNWJerW7Zrs56j8/gPBHi6bQfAQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GWUcbwuJkqAournHujBy+X82Zo7gJidT+oH4p4cW7SX/8Ur1Vsd7IVvHGiD1Nu+yWvVCfzJS10UoPRKEQ7WKnqaqnGqBrBQ6ODqJ2/Pr18QlBZKayUHofxL7u5NR0mlkOlZkIAhhoyyCFGtrMxIuAHYHyklEMKTBORBcPXs9I7w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=e/z+/n06; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="e/z+/n06" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 95834143D; Fri, 2 Oct 2026 08:15:09 -0700 (PDT) Received: from [10.57.8.170] (unknown [10.57.8.170]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8291F3F85F; Fri, 2 Oct 2026 08:15:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790954113; bh=ELvA9eECm9X8xz8cLNWJerW7Zrs56j8/gPBHi6bQfAQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=e/z+/n06DSw8s8JlOWXlAtjzjYm25fc9jLHgrTo3RhyWsmmAIyy3j08qP4TzIdjSS i1XDER7EGZI78JBxCEhHmrhsg6HJecq/80SfKLh1Si6/jmxdcksfoV7sMgyWi7U8LA kq+LppQbltELEHrEHjQrIFbsWBlmpXgBCDEFpcrQ= Message-ID: <10563362-5964-4ef7-b5d7-fe1d67ce4adb@arm.com> Date: Fri, 2 Oct 2026 16:15:07 +0100 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 v21 05/23] KVM: arm64: Track the type of VM in kvm_arch Content-Language: en-GB To: Marc Zyngier , 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 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> From: Suzuki K Poulose In-Reply-To: <86pkxs2npx.wl-maz@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 02/10/2026 15:15, Marc Zyngier wrote: > 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)) { 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() Suzuki > /* Cannot modify memslots once a pVM has run. */ > if (pkvm_hyp_vm_is_created(kvm) && > (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) { >