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Thu, 7 Sep 2023 11:15:00 -0700 From: To: , , , , , CC: , , , , , , , , , , , Subject: [PATCH v1 1/2] KVM: arm64: determine memory type from VMA Date: Thu, 7 Sep 2023 11:14:58 -0700 Message-ID: <20230907181459.18145-2-ankita@nvidia.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230907181459.18145-1-ankita@nvidia.com> References: <20230907181459.18145-1-ankita@nvidia.com> MIME-Version: 1.0 X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000FCC5:EE_|DS0PR12MB6630:EE_ X-MS-Office365-Filtering-Correlation-Id: 44698d35-ff27-4d8c-33de-08dbafce5ed2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 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)(396003)(376002)(136003)(346002)(186009)(82310400011)(1800799009)(451199024)(40470700004)(36840700001)(46966006)(40480700001)(478600001)(336012)(426003)(83380400001)(40460700003)(36756003)(7696005)(26005)(7636003)(356005)(2616005)(82740400003)(1076003)(36860700001)(316002)(54906003)(47076005)(8676002)(2906002)(41300700001)(8936002)(4326008)(5660300002)(86362001)(70586007)(70206006)(110136005)(2876002);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Sep 2023 18:15:09.0608 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 44698d35-ff27-4d8c-33de-08dbafce5ed2 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: CY4PEPF0000FCC5.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB6630 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Ankit Agrawal Currently KVM determines if a VMA is pointing at IO memory by checking pfn_is_map_memory(). However, the MM already gives us a way to tell what kind of memory it is by inspecting the VMA. Replace pfn_is_map_memory() with a check on the VMA pgprot to determine if the memory is IO and thus needs stage-2 device mapping. The VMA's pgprot is tested to determine the memory type with the following mapping: pgprot_noncached MT_DEVICE_nGnRnE device pgprot_writecombine MT_NORMAL_NC device pgprot_device MT_DEVICE_nGnRE device pgprot_tagged MT_NORMAL_TAGGED RAM This patch solves a problems where it is possible for the kernel to have VMAs pointing at cachable memory without causing pfn_is_map_memory() to be true, eg DAX memremap cases and CXL/pre-CXL devices. This memory is now properly marked as cachable in KVM. Unfortunately when FWB is not enabled, the kernel expects to naively do cache management by flushing the memory using an address in the kernel's map. This does not work in several of the newly allowed cases such as dcache_clean_inval_poc(). Check whether the targeted pfn and its mapping KVA is valid in case the FWB is absent before continuing. Signed-off-by: Ankit Agrawal --- arch/arm64/include/asm/kvm_pgtable.h | 8 ++++++ arch/arm64/kvm/hyp/pgtable.c | 2 +- arch/arm64/kvm/mmu.c | 40 +++++++++++++++++++++++++--- 3 files changed, 45 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/= kvm_pgtable.h index d3e354bb8351..0579dbe958b9 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -430,6 +430,14 @@ u64 kvm_pgtable_hyp_unmap(struct kvm_pgtable *pgt, u64= addr, u64 size); */ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift); =20 +/** + * stage2_has_fwb() - Determine whether FWB is supported + * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*() + * + * Return: True if FWB is supported. + */ +bool stage2_has_fwb(struct kvm_pgtable *pgt); + /** * kvm_pgtable_stage2_pgd_size() - Helper to compute size of a stage-2 PGD * @vtcr: Content of the VTCR register. diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index f155b8c9e98c..ccd291b6893d 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -662,7 +662,7 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift) return vtcr; } =20 -static bool stage2_has_fwb(struct kvm_pgtable *pgt) +bool stage2_has_fwb(struct kvm_pgtable *pgt) { if (!cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) return false; diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 482280fe22d7..79f1caaa08a0 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1391,6 +1391,15 @@ static bool kvm_vma_mte_allowed(struct vm_area_struc= t *vma) return vma->vm_flags & VM_MTE_ALLOWED; } =20 +/* + * Determine the memory region cacheability from VMA's pgprot. This + * is used to set the stage 2 PTEs. + */ +static unsigned long mapping_type(pgprot_t page_prot) +{ + return FIELD_GET(PTE_ATTRINDX_MASK, pgprot_val(page_prot)); +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_memory_slot *memslot, unsigned long hva, unsigned long fault_status) @@ -1490,6 +1499,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phy= s_addr_t fault_ipa, gfn =3D fault_ipa >> PAGE_SHIFT; mte_allowed =3D kvm_vma_mte_allowed(vma); =20 + /* + * Figure out the memory type based on the user va mapping properties + * Only MT_DEVICE_nGnRE and MT_DEVICE_nGnRnE will be set using + * pgprot_device() and pgprot_noncached() respectively. + */ + if ((mapping_type(vma->vm_page_prot) =3D=3D MT_DEVICE_nGnRE) || + (mapping_type(vma->vm_page_prot) =3D=3D MT_DEVICE_nGnRnE) || + (mapping_type(vma->vm_page_prot) =3D=3D MT_NORMAL_NC)) + prot |=3D KVM_PGTABLE_PROT_DEVICE; + else if (cpus_have_const_cap(ARM64_HAS_CACHE_DIC)) + prot |=3D KVM_PGTABLE_PROT_X; + /* Don't use the VMA after the unlock -- it may have vanished */ vma =3D NULL; =20 @@ -1576,10 +1597,21 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, ph= ys_addr_t fault_ipa, if (exec_fault) prot |=3D KVM_PGTABLE_PROT_X; =20 - if (device) - prot |=3D KVM_PGTABLE_PROT_DEVICE; - else if (cpus_have_const_cap(ARM64_HAS_CACHE_DIC)) - prot |=3D KVM_PGTABLE_PROT_X; + /* + * When FWB is unsupported KVM needs to do cache flushes + * (via dcache_clean_inval_poc()) of the underlying memory. This is + * only possible if the memory is already mapped into the kernel map + * at the usual spot. + * + * Validate that there is a struct page for the PFN which maps + * to the KVA that the flushing code expects. + */ + if (!stage2_has_fwb(pgt) && + !(pfn_valid(pfn) && + page_to_virt(pfn_to_page(pfn)) =3D=3D kvm_host_va(PFN_PHYS(pfn)))) { + ret =3D -EINVAL; + goto out_unlock; + } =20 /* * Under the premise of getting a FSC_PERM fault, we just need to relax --=20 2.17.1 From nobody Fri Dec 19 16:05:37 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C72DCEC874B for ; Thu, 7 Sep 2023 18:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343688AbjIGSPl (ORCPT ); Thu, 7 Sep 2023 14:15:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242208AbjIGSPi (ORCPT ); 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Sep 2023 18:15:09.5608 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 567b9141-f874-4537-7f10-08dbafce5f1e 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: CY4PEPF0000FCC5.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6469 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ankit Agrawal Linux allows device drivers to map IO memory on a per-page basis using "write combining" or WC. This is often done using pgprot_writecombing(). The driver knows which pages can support WC access and the proper programming model to generate this IO. Generally the use case is to boost performance by using write combining to generate larger PCIe MemWr TLPs. Allow VMs to select DEVICE_* or NORMAL_NC on a page by page basis for all IO memory. This puts the VM in charge of the memory attributes, and removes the KVM override to DEVICE_nGnRE. Ultimately this makes pgprot_writecombing() work correctly in VMs and allows drivers like mlx5 to fully operate their HW. After some discussions with ARM and CPU architects we reached the conclusion there was no need for KVM to prevent the VM from selecting between DEVICE_* and NORMAL_NC for IO memory in VMs. There was a fear that NORMAL_NC could result in uncontained failures, but upon deeper analysis it turns out there are already possible cases for uncontained failures with DEVICE types too. Ultimately the platform must be implemented in a way that ensures that all DEVICE_* and NORMAL_NC accesses have no uncontained failures. Fortunately real platforms do tend to implement this. This patch makes the VM's memory attributes behave as follows: =C2=A0S1=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 |=C2= =A0=C2=A0 S2=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 |=C2=A0 = Result =C2=A0NORMAL-WB=C2=A0=C2=A0=C2=A0=C2=A0|=C2=A0 NORMAL-NC=C2=A0=C2=A0=C2=A0= =C2=A0|=C2=A0 NORMAL-NC =C2=A0NORMAL-WT=C2=A0=C2=A0=C2=A0=C2=A0|=C2=A0 NORMAL-NC=C2=A0=C2=A0=C2=A0= =C2=A0|=C2=A0 NORMAL-NC =C2=A0NORMAL-NC=C2=A0=C2=A0=C2=A0=C2=A0|=C2=A0 NORMAL-NC=C2=A0=C2=A0=C2=A0= =C2=A0|=C2=A0 NORMAL-NC =C2=A0DEVICE=C2=A0|=C2=A0 NORMAL-NC=C2=A0=C2=A0=C2=A0=C2=A0|=C2=A0 DE= VICE See section D8.5.5 of DDI0487_I_a_a-profile_architecture_reference_manual.p= df for details. Signed-off-by: Ankit Agrawal Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/memory.h | 2 ++ arch/arm64/kvm/hyp/pgtable.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memor= y.h index fde4186cc387..c247e5f29d5a 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -147,6 +147,7 @@ * Memory types for Stage-2 translation */ #define MT_S2_NORMAL 0xf +#define MT_S2_NORMAL_NC 0x5 #define MT_S2_DEVICE_nGnRE 0x1 =20 /* @@ -154,6 +155,7 @@ * Stage-2 enforces Normal-WB and Device-nGnRE */ #define MT_S2_FWB_NORMAL 6 +#define MT_S2_FWB_NORMAL_NC 5 #define MT_S2_FWB_DEVICE_nGnRE 1 =20 #ifdef CONFIG_ARM64_4K_PAGES diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index ccd291b6893d..a80949002191 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -696,7 +696,7 @@ static int stage2_set_prot_attr(struct kvm_pgtable *pgt= , enum kvm_pgtable_prot p kvm_pte_t *ptep) { bool device =3D prot & KVM_PGTABLE_PROT_DEVICE; - kvm_pte_t attr =3D device ? KVM_S2_MEMATTR(pgt, DEVICE_nGnRE) : + kvm_pte_t attr =3D device ? KVM_S2_MEMATTR(pgt, NORMAL_NC) : KVM_S2_MEMATTR(pgt, NORMAL); u32 sh =3D KVM_PTE_LEAF_ATTR_LO_S2_SH_IS; =20 --=20 2.17.1