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Mon, 18 Dec 2023 01:07:42 -0800 From: To: , , , , , , , , , , , , , , , CC: , , , , , , , , , , , , , Subject: [PATCH v4 2/3] kvm: arm64: set io memory s2 pte as normalnc for vfio pci devices Date: Mon, 18 Dec 2023 14:37:18 +0530 Message-ID: <20231218090719.22250-3-ankita@nvidia.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20231218090719.22250-1-ankita@nvidia.com> References: <20231218090719.22250-1-ankita@nvidia.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN1PEPF0002529D:EE_|DM6PR12MB4404:EE_ X-MS-Office365-Filtering-Correlation-Id: f51a83f0-31c9-4550-d9f6-08dbffa8d718 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: B9aaZeGx5d2XH8GrYze4BxLj38qvOTxggsMSVQSDe7PFAVLAg1NrvO5jvmfu8rMOrgXrpvRKKTA2K8RGT07+FpB61NhqGbDW38t2DFwB3kx8uLt95OWNcmvDJTDLdRIfUmFbJknbbmrvu0cvrDZ41M2YglmILQNcuJphrGOzau9zi+Cg6JTrsPNZjYNBVWiAyGrFtI2YL3qXWLBaO83LdnhHhl1e3TG5NyztdTpKR1ill7FZPAt3td38kOMwg8H/jmC1B38PnME++e5cL98A8KlEOdqeKKHfsbWjgKS5RWOj+wEnlH1bkd8ONgG0kEKg0MwAmlNamMTBeGc+D0otDO9lLJoslbh721a8R8lrzyjcLDW0Le616xOWAIpjLE1VfisbWoewMXrNOMfYl1mi5muGGhwj7dsys35msHysLhfq+4McVB8fALhgaYERObWR33bcZnzy8Af0/e5ZhRC9xt9zsPgEMvtZrpl2AjfBbQgxv5+OZhMWdiqtdhPhgzfza53fT9HP64AoNBLKyYe5KTz/OZo6KwN0mJjY/fXGEG52sRDs5B3ox5JHGh0scqWrJOtrbUEDWssmDRwGRPt5CDcHv9QqqB/9cGc80pqoFgkv2i2KCM++HvIQPW1qi4w3NNWeE7E6M5etl822rizxwjHGP3sCaa3VwQ5YfxOWsf4r9lSbMe4hwnZxgUInTRlXURrAELFmCtkfQqiiNS2oDcq+VYRxE9iN1kanEyfeQ7ZAlhKTLUwwU9pJUb44gWvIqtoqfw9TWqJEStXQA1uU8CEclrN49OyTFNyHwhuf8lKWraPVw76SHfJyg/PvOBrzD6ZU5nJnSOwxlQmj1DIPc5J7p2WeTyISdplSBQEUJ/w= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230031)(4636009)(39860400002)(346002)(396003)(376002)(136003)(230173577357003)(230273577357003)(230922051799003)(82310400011)(1800799012)(186009)(64100799003)(451199024)(40470700004)(46966006)(36840700001)(2616005)(40480700001)(7696005)(26005)(7416002)(5660300002)(478600001)(6666004)(83380400001)(426003)(336012)(1076003)(70206006)(54906003)(70586007)(316002)(110136005)(40460700003)(4326008)(47076005)(8936002)(8676002)(921008)(2876002)(2906002)(86362001)(41300700001)(36860700001)(82740400003)(356005)(7636003)(36756003)(83996005)(2101003);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Dec 2023 09:08:02.9969 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: f51a83f0-31c9-4550-d9f6-08dbffa8d718 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF0002529D.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4404 From: Ankit Agrawal To provide VM with the ability to get device IO memory with NormalNC property, map device MMIO in KVM for ARM64 at stage2 as NormalNC. Having NormalNC S2 default puts guests in control (based on [1], "Combining stage 1 and stage 2 memory type attributes") of device MMIO regions memory mappings. The rules are summarized below: ([(S1) - stage1], [(S2) - stage 2]) S1 | S2 | Result NORMAL-WB | NORMAL-NC | NORMAL-NC NORMAL-WT | NORMAL-NC | NORMAL-NC NORMAL-NC | NORMAL-NC | NORMAL-NC DEVICE | NORMAL-NC | DEVICE Generalizing this to non PCI devices may be problematic. E.g. GICv2 vCPU interface, which is effectively a shared peripheral, can allow a guest to affect another guest's interrupt distribution. The issue may be solved by limiting the relaxation to mappings that have a user VMA. Still There is insufficient information and uncertainity in the behavior of non PCI driver. Hence caution is maintained and the change is restricted to the VFIO-PCI devices. PCIe on the other hand is safe because the PCI bridge does not generate errors, and thus do not cause uncontained failures. A new flag VM_VFIO_ALLOW_WC to indicate KVM that the device is WC capable. KVM use this flag to activate the code. This could be extended to other devices in the future once that is deemed safe. [1] section D8.5.5 of DDI0487J_a_a-profile_architecture_reference_manual.pdf Signed-off-by: Ankit Agrawal Suggested-by: Catalin Marinas Acked-by: Jason Gunthorpe Tested-by: Ankit Agrawal --- arch/arm64/kvm/mmu.c | 18 ++++++++++++++---- include/linux/mm.h | 13 +++++++++++++ 2 files changed, 27 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index d14504821b79..e1e6847a793b 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1381,7 +1381,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, int ret = 0; bool write_fault, writable, force_pte = false; bool exec_fault, mte_allowed; - bool device = false; + bool device = false, vfio_allow_wc = false; unsigned long mmu_seq; struct kvm *kvm = vcpu->kvm; struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; @@ -1472,6 +1472,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, gfn = fault_ipa >> PAGE_SHIFT; mte_allowed = kvm_vma_mte_allowed(vma); + vfio_allow_wc = (vma->vm_flags & VM_VFIO_ALLOW_WC); + /* Don't use the VMA after the unlock -- it may have vanished */ vma = NULL; @@ -1557,10 +1559,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, if (exec_fault) prot |= KVM_PGTABLE_PROT_X; - if (device) - prot |= KVM_PGTABLE_PROT_DEVICE; - else if (cpus_have_final_cap(ARM64_HAS_CACHE_DIC)) + if (device) { + /* + * To provide VM with the ability to get device IO memory + * with NormalNC property, map device MMIO as NormalNC in S2. + */ + if (vfio_allow_wc) + prot |= KVM_PGTABLE_PROT_NORMAL_NC; + else + prot |= KVM_PGTABLE_PROT_DEVICE; + } else if (cpus_have_final_cap(ARM64_HAS_CACHE_DIC)) { prot |= KVM_PGTABLE_PROT_X; + } /* * Under the premise of getting a FSC_PERM fault, we just need to relax diff --git a/include/linux/mm.h b/include/linux/mm.h index 2bea89dc0bdf..d2f0f969875c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -391,6 +391,19 @@ extern unsigned int kobjsize(const void *objp); # define VM_UFFD_MINOR VM_NONE #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ +/* This flag is used to connect VFIO to arch specific KVM code. It + * indicates that the memory under this VMA is safe for use with any + * non-cachable memory type inside KVM. Some VFIO devices, on some + * platforms, are thought to be unsafe and can cause machine crashes if + * KVM does not lock down the memory type. + */ +#ifdef CONFIG_64BIT +#define VM_VFIO_ALLOW_WC_BIT 39 +#define VM_VFIO_ALLOW_WC BIT(VM_VFIO_ALLOW_WC_BIT) +#else +#define VM_VFIO_ALLOW_WC VM_NONE +#endif + /* Bits set in the VMA until the stack is in its final location */ #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY)