diff options
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 13 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kvm_mmu.h | 18 | ||||
| -rw-r--r-- | arch/arm64/kvm/arm.c | 7 | ||||
| -rw-r--r-- | arch/arm64/kvm/mmu.c | 88 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 |
5 files changed, 103 insertions, 24 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 9abf93ee5f65..53e0179d5294 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8585,7 +8585,7 @@ ENOSYS for the others. When enabled, KVM will exit to userspace with KVM_EXIT_SYSTEM_EVENT of type KVM_SYSTEM_EVENT_SUSPEND to process the guest suspend request. -7.37 KVM_CAP_ARM_WRITABLE_IMP_ID_REGS +7.42 KVM_CAP_ARM_WRITABLE_IMP_ID_REGS ------------------------------------- :Architectures: arm64 @@ -8614,6 +8614,17 @@ given VM. When this capability is enabled, KVM resets the VCPU when setting MP_STATE_INIT_RECEIVED through IOCTL. The original MP_STATE is preserved. +7.43 KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED +------------------------------------------- + +:Architectures: arm64 +:Target: VM +:Parameters: None + +This capability indicate to the userspace whether a PFNMAP memory region +can be safely mapped as cacheable. This relies on the presence of +force write back (FWB) feature support on the hardware. + 8. Other capabilities. ====================== diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index b98ac6aa631f..ae563ebd6aee 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -371,6 +371,24 @@ static inline void kvm_fault_unlock(struct kvm *kvm) read_unlock(&kvm->mmu_lock); } +/* + * ARM64 KVM relies on a simple conversion from physaddr to a kernel + * virtual address (KVA) when it does cache maintenance as the CMO + * instructions work on virtual addresses. This is incompatible with + * VM_PFNMAP VMAs which may not have a kernel direct mapping to a + * virtual address. + * + * With S2FWB and CACHE DIC features, KVM need not do cache flushing + * and CMOs are NOP'd. This has the effect of no longer requiring a + * KVA for addresses mapped into the S2. The presence of these features + * are thus necessary to support cacheable S2 mapping of VM_PFNMAP. + */ +static inline bool kvm_supports_cacheable_pfnmap(void) +{ + return cpus_have_final_cap(ARM64_HAS_STAGE2_FWB) && + cpus_have_final_cap(ARM64_HAS_CACHE_DIC); +} + #ifdef CONFIG_PTDUMP_STAGE2_DEBUGFS void kvm_s2_ptdump_create_debugfs(struct kvm *kvm); #else diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 38a91bb5d4c7..25609aab032c 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -408,6 +408,13 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES: r = BIT(0); break; + case KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED: + if (!kvm) + r = -EINVAL; + else + r = kvm_supports_cacheable_pfnmap(); + break; + default: r = 0; } diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 2942ec92c5a4..3a9e2248f82d 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -193,11 +193,6 @@ int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, return 0; } -static bool kvm_is_device_pfn(unsigned long pfn) -{ - return !pfn_is_map_memory(pfn); -} - static void *stage2_memcache_zalloc_page(void *arg) { struct kvm_mmu_memory_cache *mc = arg; @@ -1470,6 +1465,18 @@ static bool kvm_vma_mte_allowed(struct vm_area_struct *vma) return vma->vm_flags & VM_MTE_ALLOWED; } +static bool kvm_vma_is_cacheable(struct vm_area_struct *vma) +{ + switch (FIELD_GET(PTE_ATTRINDX_MASK, pgprot_val(vma->vm_page_prot))) { + case MT_NORMAL_NC: + case MT_DEVICE_nGnRnE: + case MT_DEVICE_nGnRE: + return false; + default: + return true; + } +} + static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, struct kvm_s2_trans *nested, struct kvm_memory_slot *memslot, unsigned long hva, @@ -1477,8 +1484,8 @@ 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, vfio_allow_any_uc = false; + bool exec_fault, mte_allowed, is_vma_cacheable; + bool s2_force_noncacheable = false, vfio_allow_any_uc = false; unsigned long mmu_seq; phys_addr_t ipa = fault_ipa; struct kvm *kvm = vcpu->kvm; @@ -1492,6 +1499,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; struct kvm_pgtable *pgt; struct page *page; + vm_flags_t vm_flags; enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_HANDLE_FAULT | KVM_PGTABLE_WALK_SHARED; if (fault_is_perm) @@ -1619,6 +1627,10 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, vfio_allow_any_uc = vma->vm_flags & VM_ALLOW_ANY_UNCACHED; + vm_flags = vma->vm_flags; + + is_vma_cacheable = kvm_vma_is_cacheable(vma); + /* Don't use the VMA after the unlock -- it may have vanished */ vma = NULL; @@ -1642,18 +1654,39 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, if (is_error_noslot_pfn(pfn)) return -EFAULT; - if (kvm_is_device_pfn(pfn)) { - /* - * If the page was identified as device early by looking at - * the VMA flags, vma_pagesize is already representing the - * largest quantity we can map. If instead it was mapped - * via __kvm_faultin_pfn(), vma_pagesize is set to PAGE_SIZE - * and must not be upgraded. - * - * In both cases, we don't let transparent_hugepage_adjust() - * change things at the last minute. - */ - device = true; + /* + * Check if this is non-struct page memory PFN, and cannot support + * CMOs. It could potentially be unsafe to access as cachable. + */ + if (vm_flags & (VM_PFNMAP | VM_MIXEDMAP) && !pfn_is_map_memory(pfn)) { + if (is_vma_cacheable) { + /* + * Whilst the VMA owner expects cacheable mapping to this + * PFN, hardware also has to support the FWB and CACHE DIC + * features. + * + * ARM64 KVM relies on kernel VA mapping to the PFN to + * perform cache maintenance as the CMO instructions work on + * virtual addresses. VM_PFNMAP region are not necessarily + * mapped to a KVA and hence the presence of hardware features + * S2FWB and CACHE DIC are mandatory to avoid the need for + * cache maintenance. + */ + if (!kvm_supports_cacheable_pfnmap()) + return -EFAULT; + } else { + /* + * If the page was identified as device early by looking at + * the VMA flags, vma_pagesize is already representing the + * largest quantity we can map. If instead it was mapped + * via __kvm_faultin_pfn(), vma_pagesize is set to PAGE_SIZE + * and must not be upgraded. + * + * In both cases, we don't let transparent_hugepage_adjust() + * change things at the last minute. + */ + s2_force_noncacheable = true; + } } else if (logging_active && !write_fault) { /* * Only actually map the page as writable if this was a write @@ -1662,7 +1695,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, writable = false; } - if (exec_fault && device) + if (exec_fault && s2_force_noncacheable) return -ENOEXEC; /* @@ -1695,7 +1728,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * If we are not forced to use page mapping, check if we are * backed by a THP and thus use block mapping if possible. */ - if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) { + if (vma_pagesize == PAGE_SIZE && !(force_pte || s2_force_noncacheable)) { if (fault_is_perm && fault_granule > PAGE_SIZE) vma_pagesize = fault_granule; else @@ -1709,7 +1742,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, } } - if (!fault_is_perm && !device && kvm_has_mte(kvm)) { + if (!fault_is_perm && !s2_force_noncacheable && kvm_has_mte(kvm)) { /* Check the VMM hasn't introduced a new disallowed VMA */ if (mte_allowed) { sanitise_mte_tags(kvm, pfn, vma_pagesize); @@ -1725,7 +1758,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, if (exec_fault) prot |= KVM_PGTABLE_PROT_X; - if (device) { + if (s2_force_noncacheable) { if (vfio_allow_any_uc) prot |= KVM_PGTABLE_PROT_NORMAL_NC; else @@ -2221,6 +2254,15 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, ret = -EINVAL; break; } + + /* + * Cacheable PFNMAP is allowed only if the hardware + * supports it. + */ + if (kvm_vma_is_cacheable(vma) && !kvm_supports_cacheable_pfnmap()) { + ret = -EINVAL; + break; + } } hva = min(reg_end, vma->vm_end); } while (hva < reg_end); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 37891580d05d..e4e566ff348b 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -956,6 +956,7 @@ struct kvm_enable_cap { #define KVM_CAP_ARM_EL2 240 #define KVM_CAP_ARM_EL2_E2H0 241 #define KVM_CAP_RISCV_MP_STATE_RESET 242 +#define KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED 243 struct kvm_irq_routing_irqchip { __u32 irqchip; |