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author | Alex Williamson <alex.williamson@redhat.com> | 2024-03-05 02:08:46 +0300 |
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committer | Alex Williamson <alex.williamson@redhat.com> | 2024-03-05 02:08:46 +0300 |
commit | c71f08cfb3c621acd537a591e2230eb17562ac7e (patch) | |
tree | 3a81e0f412ddd1ab2091450ee13798a9b49fadd7 | |
parent | ec29d22caea85d9b391f9df780a0e61597f18778 (diff) | |
parent | a39d3a966a090989b89c0287a67cd98c85ae2f52 (diff) | |
download | linux-c71f08cfb3c621acd537a591e2230eb17562ac7e.tar.xz |
Merge branch 'kvm-arm64/vfio-normal-nc' of https://git.kernel.org/pub/scm/linux/kernel/git/oupton/linux into v6.9/vfio/next
-rw-r--r-- | arch/arm64/include/asm/kvm_pgtable.h | 2 | ||||
-rw-r--r-- | arch/arm64/include/asm/memory.h | 2 | ||||
-rw-r--r-- | arch/arm64/kvm/hyp/pgtable.c | 24 | ||||
-rw-r--r-- | arch/arm64/kvm/mmu.c | 14 | ||||
-rw-r--r-- | drivers/vfio/pci/vfio_pci_core.c | 19 | ||||
-rw-r--r-- | include/linux/mm.h | 14 |
6 files changed, 65 insertions, 10 deletions
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index cfdf40f734b1..19278dfe7978 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -197,6 +197,7 @@ enum kvm_pgtable_stage2_flags { * @KVM_PGTABLE_PROT_W: Write permission. * @KVM_PGTABLE_PROT_R: Read permission. * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + * @KVM_PGTABLE_PROT_NORMAL_NC: Normal noncacheable attributes. * @KVM_PGTABLE_PROT_SW0: Software bit 0. * @KVM_PGTABLE_PROT_SW1: Software bit 1. * @KVM_PGTABLE_PROT_SW2: Software bit 2. @@ -208,6 +209,7 @@ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_R = BIT(2), KVM_PGTABLE_PROT_DEVICE = BIT(3), + KVM_PGTABLE_PROT_NORMAL_NC = BIT(4), KVM_PGTABLE_PROT_SW0 = BIT(55), KVM_PGTABLE_PROT_SW1 = BIT(56), diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index d82305ab420f..449ca2ff1df6 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -173,6 +173,7 @@ * Memory types for Stage-2 translation */ #define MT_S2_NORMAL 0xf +#define MT_S2_NORMAL_NC 0x5 #define MT_S2_DEVICE_nGnRE 0x1 /* @@ -180,6 +181,7 @@ * 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 #ifdef CONFIG_ARM64_4K_PAGES diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index ab9d05fcf98b..3fae5830f8d2 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -717,15 +717,29 @@ void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu, static int stage2_set_prot_attr(struct kvm_pgtable *pgt, enum kvm_pgtable_prot prot, kvm_pte_t *ptep) { - bool device = prot & KVM_PGTABLE_PROT_DEVICE; - kvm_pte_t attr = device ? KVM_S2_MEMATTR(pgt, DEVICE_nGnRE) : - KVM_S2_MEMATTR(pgt, NORMAL); + kvm_pte_t attr; u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS; + switch (prot & (KVM_PGTABLE_PROT_DEVICE | + KVM_PGTABLE_PROT_NORMAL_NC)) { + case KVM_PGTABLE_PROT_DEVICE | KVM_PGTABLE_PROT_NORMAL_NC: + return -EINVAL; + case KVM_PGTABLE_PROT_DEVICE: + if (prot & KVM_PGTABLE_PROT_X) + return -EINVAL; + attr = KVM_S2_MEMATTR(pgt, DEVICE_nGnRE); + break; + case KVM_PGTABLE_PROT_NORMAL_NC: + if (prot & KVM_PGTABLE_PROT_X) + return -EINVAL; + attr = KVM_S2_MEMATTR(pgt, NORMAL_NC); + break; + default: + attr = KVM_S2_MEMATTR(pgt, NORMAL); + } + if (!(prot & KVM_PGTABLE_PROT_X)) attr |= KVM_PTE_LEAF_ATTR_HI_S2_XN; - else if (device) - return -EINVAL; if (prot & KVM_PGTABLE_PROT_R) attr |= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R; diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index d14504821b79..1742fdccb432 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_any_uc = 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_any_uc = vma->vm_flags & VM_ALLOW_ANY_UNCACHED; + /* Don't use the VMA after the unlock -- it may have vanished */ vma = NULL; @@ -1557,10 +1559,14 @@ 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) { + if (vfio_allow_any_uc) + 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/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 61aa19666050..d94d61b92c1a 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -1862,8 +1862,25 @@ int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma /* * See remap_pfn_range(), called from vfio_pci_fault() but we can't * change vm_flags within the fault handler. Set them now. + * + * VM_ALLOW_ANY_UNCACHED: The VMA flag is implemented for ARM64, + * allowing KVM stage 2 device mapping attributes to use Normal-NC + * rather than DEVICE_nGnRE, which allows guest mappings + * supporting write-combining attributes (WC). ARM does not + * architecturally guarantee this is safe, and indeed some MMIO + * regions like the GICv2 VCPU interface can trigger uncontained + * faults if Normal-NC is used. + * + * To safely use VFIO in KVM the platform must guarantee full + * safety in the guest where no action taken against a MMIO + * mapping can trigger an uncontained failure. The assumption is + * that most VFIO PCI platforms support this for both mapping types, + * at least in common flows, based on some expectations of how + * PCI IP is integrated. Hence VM_ALLOW_ANY_UNCACHED is set in + * the VMA flags. */ - vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); + vm_flags_set(vma, VM_ALLOW_ANY_UNCACHED | VM_IO | VM_PFNMAP | + VM_DONTEXPAND | VM_DONTDUMP); vma->vm_ops = &vfio_pci_mmap_ops; return 0; diff --git a/include/linux/mm.h b/include/linux/mm.h index f5a97dec5169..59576e56c58b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -391,6 +391,20 @@ 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_ALLOW_ANY_UNCACHED_BIT 39 +#define VM_ALLOW_ANY_UNCACHED BIT(VM_ALLOW_ANY_UNCACHED_BIT) +#else +#define VM_ALLOW_ANY_UNCACHED 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) |