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 CBAF53B8D4F; Tue, 6 Oct 2026 08:49:32 +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=1791276574; cv=none; b=aOpO94m0ZrG3ukoXGWsxo6snXT0ghZBcanRaw/EsK+GdguIL0hmwgaKmcI/EB/gXM5vpfFloVqiQFxsqY3PadGu38SJBVmynPhKl6vk7UVNHN11cKIU0bCKuqrgoLBiXjXPq91cl3Fo1Uq99XLIPlAMQc9Es3iYXE6PWWrK9ntA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791276574; c=relaxed/simple; bh=YISavRvpWmdsDYnih8VoBSgUz6ZqTZT9fYgZxccZo24=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NWNVTbSGkWk1x6lGR/4IsNVVQSnJPM45qDPpHGsZzQeGsZCjkQAEDiKl9zTN2se/uYsoSOrJ26vhCeoQQdP9stNFAs1/LGLyucp7KG6vbYzD/G//jqWsURJ8cOLYiX2wG1mlk8wkP5InHUO5HbVPzcMTVnBYpNvusHNfP5f3suY= 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=XprR6Fnf; 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="XprR6Fnf" 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 8185F1516; Tue, 6 Oct 2026 01:49:28 -0700 (PDT) Received: from [10.57.10.233] (unknown [10.57.10.233]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B84033F86F; Tue, 6 Oct 2026 01:49:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791276571; bh=YISavRvpWmdsDYnih8VoBSgUz6ZqTZT9fYgZxccZo24=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=XprR6FnfcIDTLyhMAIr43Z9gnXww9pKL5fQTlBTcKKUI02uJEdDo7Vl6C9L5aWja6 nl5Lk736djKuQAvvXk8cUmuk+AF+M7jY9nMcGiA3HKLcqt4nl3WHMbyC+tP4ppAUWZ EH6jVXFlj2pLUaECROcDKPXLBn1/5GUYqTDWpfwc= Message-ID: Date: Tue, 6 Oct 2026 10:49:24 +0200 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 05/23] KVM: arm64: Track the type of VM in kvm_arch Content-Language: en-GB To: Marc Zyngier 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, 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> <20261005090754.2140522-6-suzuki.poulose@arm.com> <87cxtn2pp8.wl-maz@kernel.org> From: Suzuki K Poulose In-Reply-To: <87cxtn2pp8.wl-maz@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 06/10/2026 09:33, Marc Zyngier wrote: > On Mon, 05 Oct 2026 10:07:36 +0100, > Suzuki K Poulose wrote: >> >> KVM arm64 has different types of VMs with all the different modes in which >> the hypervisor code can be run. e.g., VHE, nVHE, pKVM etc. Then there is >> protected VM and normal VMs with pKVM. We might soon add other types, >> e.g., Arm CCA Realm. So in an effort to make the handling of these >> different types of VMs a bit more friendly to the eyes, add a VM flavor to >> the kvm_arch and we could then add handlers for different operations based >> on the VM type. >> >> Keep the flavor initialisation at the beginning to allow for the detection >> early enough and fail out on any unsupported requests. >> >> With that, add wrappers for checking the "type" of a VM and replace the >> existing users with the new wrappers. >> >> Given we already have the construct of "kvm_vm_is_protected" in the core >> KVM code, use that for all confidential compute guests including Realms >> that we are about to add. Adds __VM_PROTECTED marker vm flavor to draw the >> boundary for "protected VMs". In later patches, we would add Realm VMs, >> which would also be classified as protected. >> >> Add a explicit helper to detect if a given VM is a "protected" VM under pKVM. >> Change the existing users that precisely want to check the VM type. These >> include : >> - kvm_arch_prepare_memory_region - For preventing memslot changes after >> pVM creation. >> >> All the others are retained as a wider check for confidential guest VMs. >> These are: >> - kvm_vm_ioctl_set_counter_offset - For disallowing timer offset >> configuration >> - io_mem_abort for dabt handling without valid syndrome information >> >> Both of which are true for Realms too. >> >> Realms support is restricted to VHE host and thus "kvm_vm_is_protected()" >> checks in the pkvm hyp specific code doesn't need to change, as the only >> protected guests it deals with is "protected pKVM" guests. To tighten this >> init_pkvm_hyp_vm() restricts the hyp copy of the vm_flavor to the ones it >> supports. >> >> vcpu_is_protected() usage from nVHE hyp code is tricky, as we need to >> convert the vcpu->kvm to the HYP VA before checking the flavor. This >> involves kern_hyp_va() usage in asm/kvm_host.h. To avoid build breaks, >> include asm/kvm_mmu.h to arm64/kvm/mmio.c. >> >> While at it move the psci_version around to keep the structure packed. >> >> Suggested-by: Marc Zyngier >> Tested-by: Gavin Shan >> Signed-off-by: Suzuki K Poulose >> --- >> Changes since v21: >> - Drop kern_hyp_va() and restrict nvhe code to always use vcpu_is_protected_pkvm() >> - Drop kvm_vm_is_unprotected_pkvm() and open code the check >> - Move psci_version field in kvm_arch around to keep the structure packed >> --- >> arch/arm64/include/asm/kvm_host.h | 42 +++++++++++++++++++++++--- >> arch/arm64/include/asm/kvm_pkvm.h | 4 +-- >> arch/arm64/kvm/arm.c | 33 ++++++++++++++++---- >> arch/arm64/kvm/hyp/include/nvhe/pkvm.h | 2 +- >> arch/arm64/kvm/hyp/nvhe/pkvm.c | 6 +++- >> arch/arm64/kvm/hyp/nvhe/switch.c | 4 +-- >> arch/arm64/kvm/hyp/nvhe/timer-sr.c | 2 +- >> arch/arm64/kvm/mmio.c | 1 + >> arch/arm64/kvm/mmu.c | 2 +- >> arch/arm64/kvm/pkvm.c | 6 ++-- >> 10 files changed, 79 insertions(+), 23 deletions(-) >> >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h >> index 286489a69dff5..dedb5df15a803 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -257,7 +257,6 @@ struct kvm_protected_vm { >> pkvm_handle_t handle; >> struct kvm_hyp_memcache teardown_mc; >> struct kvm_hyp_memcache stage2_teardown_mc; >> - bool is_protected; >> bool is_created; >> >> /* >> @@ -306,9 +305,22 @@ enum fgt_group_id { >> __NR_FGT_GROUP_IDS__ >> }; >> >> +enum kvm_arm_vm_flavor { >> + VM_NVHE, >> + VM_VHE, >> + VM_PKVM, /* Normal guests on pKVM */ >> + MARKER(__VM_PROTECTED), >> + VM_PROTECTED_PKVM, /* Protected VM */ >> + VM_FLAVOR_MAX >> +}; >> + >> struct kvm_arch { >> struct kvm_s2_mmu mmu; >> >> + enum kvm_arm_vm_flavor vm_flavor; >> + /* Mandated version of PSCI */ >> + u32 psci_version; >> + >> /* >> * Fine-Grained UNDEF, mimicking the FGT layout defined by the >> * architecture. We track them globally, as we present the >> @@ -332,9 +344,6 @@ struct kvm_arch { >> /* Timers */ >> struct arch_timer_vm_data timer_data; >> >> - /* Mandated version of PSCI */ >> - u32 psci_version; >> - >> /* Protects VM-scoped configuration data */ >> struct mutex config_lock; >> >> @@ -1504,9 +1513,32 @@ struct kvm *kvm_arch_alloc_vm(void); >> >> #define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE >> >> -#define kvm_vm_is_protected(kvm) (is_protected_kvm_enabled() && (kvm)->arch.pkvm.is_protected) >> +#define kvm_vm_is_protected(kvm) ((kvm)->arch.vm_flavor >= __VM_PROTECTED) >> >> +#ifdef __KVM_NVHE_HYPERVISOR__ >> +/* >> + * 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. Always vcpu_is_protected_pkvm(), which is > > Always *use*? Ack > >> + * gated on is_protected_kvm_enabled(). >> + */ >> +#define vcpu_is_protected(vcpu) BUILD_BUG_ON(1) >> +#else >> #define vcpu_is_protected(vcpu) kvm_vm_is_protected((vcpu)->kvm) >> +#endif >> + >> +#define kvm_vm_is_protected_pkvm(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) \ >> + ({ \ >> + struct kvm *__kvm = READ_ONCE((vcpu)->kvm); \ >> + \ >> + (__kvm && kvm_vm_is_protected_pkvm(__kvm)); \ >> + }) > > But why do we have to have this pkvm-specific stuff? I thought we had > established it is not necessary in [1]. My bad. I need to wear the glasses :-( > > I really want to avoid any backend-specific helper, as it really gets > in the way of maintainability. Agreed. I will fix this. Apologies Cheers Suzuki > > M. > > [1] https://lore.kernel.org/r/86pkxs2npx.wl-maz@kernel.org > >