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author | Marc Zyngier <maz@kernel.org> | 2023-01-05 15:25:54 +0000 |
---|---|---|
committer | Marc Zyngier <maz@kernel.org> | 2023-01-05 15:25:54 +0000 |
commit | afbb1b1caef7fb8b23f31f32162dd5756d877dd5 (patch) | |
tree | 628e6df3305d1c38ba277363bd37b82533da518b | |
parent | d5b4d07bb361fa893244cf55ce5eb053e29b5562 (diff) | |
parent | b0803ba72b558957fdcfe845939ee788b7ce5919 (diff) | |
download | linux-stable-afbb1b1caef7fb8b23f31f32162dd5756d877dd5.tar.gz linux-stable-afbb1b1caef7fb8b23f31f32162dd5756d877dd5.tar.bz2 linux-stable-afbb1b1caef7fb8b23f31f32162dd5756d877dd5.zip |
Merge branch kvm-arm64/s1ptw-write-fault into kvmarm-master/fixes
* kvm-arm64/s1ptw-write-fault:
: .
: Fix S1PTW fault handling that was until then always taken
: as a write. From the cover letter:
:
: `Recent developments on the EFI front have resulted in guests that
: simply won't boot if the page tables are in a read-only memslot and
: that you're a bit unlucky in the way S2 gets paged in... The core
: issue is related to the fact that we treat a S1PTW as a write, which
: is close enough to what needs to be done. Until to get to RO memslots.
:
: The first patch fixes this and is definitely a stable candidate. It
: splits the faulting of page tables in two steps (RO translation fault,
: followed by a writable permission fault -- should it even happen).
: The second one documents the slightly odd behaviour of PTW writes to
: RO memslot, which do not result in a KVM_MMIO exit. The last patch is
: totally optional, only tangentially related, and randomly repainting
: stuff (maybe that's contagious, who knows)."
:
: .
KVM: arm64: Convert FSC_* over to ESR_ELx_FSC_*
KVM: arm64: Document the behaviour of S1PTW faults on RO memslots
KVM: arm64: Fix S1PTW handling on RO memslots
Signed-off-by: Marc Zyngier <maz@kernel.org>
-rw-r--r-- | Documentation/virt/kvm/api.rst | 8 | ||||
-rw-r--r-- | arch/arm64/include/asm/esr.h | 9 | ||||
-rw-r--r-- | arch/arm64/include/asm/kvm_arm.h | 15 | ||||
-rw-r--r-- | arch/arm64/include/asm/kvm_emulate.h | 42 | ||||
-rw-r--r-- | arch/arm64/kvm/hyp/include/hyp/fault.h | 2 | ||||
-rw-r--r-- | arch/arm64/kvm/hyp/include/hyp/switch.h | 2 | ||||
-rw-r--r-- | arch/arm64/kvm/mmu.c | 21 |
7 files changed, 61 insertions, 38 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index deb494f759ed..dbed78a9c31b 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1354,6 +1354,14 @@ the memory region are automatically reflected into the guest. For example, an mmap() that affects the region will be made visible immediately. Another example is madvise(MADV_DROP). +Note: On arm64, a write generated by the page-table walker (to update +the Access and Dirty flags, for example) never results in a +KVM_EXIT_MMIO exit when the slot has the KVM_MEM_READONLY flag. This +is because KVM cannot provide the data that would be written by the +page-table walker, making it impossible to emulate the access. +Instead, an abort (data abort if the cause of the page-table update +was a load or a store, instruction abort if it was an instruction +fetch) is injected in the guest. 4.36 KVM_SET_TSS_ADDR --------------------- diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index 15b34fbfca66..206de10524e3 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -114,6 +114,15 @@ #define ESR_ELx_FSC_ACCESS (0x08) #define ESR_ELx_FSC_FAULT (0x04) #define ESR_ELx_FSC_PERM (0x0C) +#define ESR_ELx_FSC_SEA_TTW0 (0x14) +#define ESR_ELx_FSC_SEA_TTW1 (0x15) +#define ESR_ELx_FSC_SEA_TTW2 (0x16) +#define ESR_ELx_FSC_SEA_TTW3 (0x17) +#define ESR_ELx_FSC_SECC (0x18) +#define ESR_ELx_FSC_SECC_TTW0 (0x1c) +#define ESR_ELx_FSC_SECC_TTW1 (0x1d) +#define ESR_ELx_FSC_SECC_TTW2 (0x1e) +#define ESR_ELx_FSC_SECC_TTW3 (0x1f) /* ISS field definitions for Data Aborts */ #define ESR_ELx_ISV_SHIFT (24) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 0df3fc3a0173..26b0c97df986 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -319,21 +319,6 @@ BIT(18) | \ GENMASK(16, 15)) -/* For compatibility with fault code shared with 32-bit */ -#define FSC_FAULT ESR_ELx_FSC_FAULT -#define FSC_ACCESS ESR_ELx_FSC_ACCESS -#define FSC_PERM ESR_ELx_FSC_PERM -#define FSC_SEA ESR_ELx_FSC_EXTABT -#define FSC_SEA_TTW0 (0x14) -#define FSC_SEA_TTW1 (0x15) -#define FSC_SEA_TTW2 (0x16) -#define FSC_SEA_TTW3 (0x17) -#define FSC_SECC (0x18) -#define FSC_SECC_TTW0 (0x1c) -#define FSC_SECC_TTW1 (0x1d) -#define FSC_SECC_TTW2 (0x1e) -#define FSC_SECC_TTW3 (0x1f) - /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */ #define HPFAR_MASK (~UL(0xf)) /* diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h index 9bdba47f7e14..193583df2d9c 100644 --- a/arch/arm64/include/asm/kvm_emulate.h +++ b/arch/arm64/include/asm/kvm_emulate.h @@ -349,16 +349,16 @@ static __always_inline u8 kvm_vcpu_trap_get_fault_level(const struct kvm_vcpu *v static __always_inline bool kvm_vcpu_abt_issea(const struct kvm_vcpu *vcpu) { switch (kvm_vcpu_trap_get_fault(vcpu)) { - case FSC_SEA: - case FSC_SEA_TTW0: - case FSC_SEA_TTW1: - case FSC_SEA_TTW2: - case FSC_SEA_TTW3: - case FSC_SECC: - case FSC_SECC_TTW0: - case FSC_SECC_TTW1: - case FSC_SECC_TTW2: - case FSC_SECC_TTW3: + case ESR_ELx_FSC_EXTABT: + case ESR_ELx_FSC_SEA_TTW0: + case ESR_ELx_FSC_SEA_TTW1: + case ESR_ELx_FSC_SEA_TTW2: + case ESR_ELx_FSC_SEA_TTW3: + case ESR_ELx_FSC_SECC: + case ESR_ELx_FSC_SECC_TTW0: + case ESR_ELx_FSC_SECC_TTW1: + case ESR_ELx_FSC_SECC_TTW2: + case ESR_ELx_FSC_SECC_TTW3: return true; default: return false; @@ -373,8 +373,26 @@ static __always_inline int kvm_vcpu_sys_get_rt(struct kvm_vcpu *vcpu) static inline bool kvm_is_write_fault(struct kvm_vcpu *vcpu) { - if (kvm_vcpu_abt_iss1tw(vcpu)) - return true; + if (kvm_vcpu_abt_iss1tw(vcpu)) { + /* + * Only a permission fault on a S1PTW should be + * considered as a write. Otherwise, page tables baked + * in a read-only memslot will result in an exception + * being delivered in the guest. + * + * The drawback is that we end-up faulting twice if the + * guest is using any of HW AF/DB: a translation fault + * to map the page containing the PT (read only at + * first), then a permission fault to allow the flags + * to be set. + */ + switch (kvm_vcpu_trap_get_fault_type(vcpu)) { + case ESR_ELx_FSC_PERM: + return true; + default: + return false; + } + } if (kvm_vcpu_trap_is_iabt(vcpu)) return false; diff --git a/arch/arm64/kvm/hyp/include/hyp/fault.h b/arch/arm64/kvm/hyp/include/hyp/fault.h index 1b8a2dcd712f..9ddcfe2c3e57 100644 --- a/arch/arm64/kvm/hyp/include/hyp/fault.h +++ b/arch/arm64/kvm/hyp/include/hyp/fault.h @@ -60,7 +60,7 @@ static inline bool __get_fault_info(u64 esr, struct kvm_vcpu_fault_info *fault) */ if (!(esr & ESR_ELx_S1PTW) && (cpus_have_final_cap(ARM64_WORKAROUND_834220) || - (esr & ESR_ELx_FSC_TYPE) == FSC_PERM)) { + (esr & ESR_ELx_FSC_TYPE) == ESR_ELx_FSC_PERM)) { if (!__translate_far_to_hpfar(far, &hpfar)) return false; } else { diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h index 3330d1b76bdd..07d37ff88a3f 100644 --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -367,7 +367,7 @@ static bool kvm_hyp_handle_dabt_low(struct kvm_vcpu *vcpu, u64 *exit_code) if (static_branch_unlikely(&vgic_v2_cpuif_trap)) { bool valid; - valid = kvm_vcpu_trap_get_fault_type(vcpu) == FSC_FAULT && + valid = kvm_vcpu_trap_get_fault_type(vcpu) == ESR_ELx_FSC_FAULT && kvm_vcpu_dabt_isvalid(vcpu) && !kvm_vcpu_abt_issea(vcpu) && !kvm_vcpu_abt_iss1tw(vcpu); diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 31d7fa4c7c14..a3ee3b605c9b 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1212,7 +1212,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu); VM_BUG_ON(write_fault && exec_fault); - if (fault_status == FSC_PERM && !write_fault && !exec_fault) { + if (fault_status == ESR_ELx_FSC_PERM && !write_fault && !exec_fault) { kvm_err("Unexpected L2 read permission error\n"); return -EFAULT; } @@ -1277,7 +1277,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * only exception to this is when dirty logging is enabled at runtime * and a write fault needs to collapse a block entry into a table. */ - if (fault_status != FSC_PERM || (logging_active && write_fault)) { + if (fault_status != ESR_ELx_FSC_PERM || + (logging_active && write_fault)) { ret = kvm_mmu_topup_memory_cache(memcache, kvm_mmu_cache_min_pages(kvm)); if (ret) @@ -1342,7 +1343,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * backed by a THP and thus use block mapping if possible. */ if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) { - if (fault_status == FSC_PERM && fault_granule > PAGE_SIZE) + if (fault_status == ESR_ELx_FSC_PERM && + fault_granule > PAGE_SIZE) vma_pagesize = fault_granule; else vma_pagesize = transparent_hugepage_adjust(kvm, memslot, @@ -1350,7 +1352,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, &fault_ipa); } - if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) { + if (fault_status != ESR_ELx_FSC_PERM && !device && kvm_has_mte(kvm)) { /* Check the VMM hasn't introduced a new disallowed VMA */ if (kvm_vma_mte_allowed(vma)) { sanitise_mte_tags(kvm, pfn, vma_pagesize); @@ -1376,7 +1378,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, * permissions only if vma_pagesize equals fault_granule. Otherwise, * kvm_pgtable_stage2_map() should be called to change block size. */ - if (fault_status == FSC_PERM && vma_pagesize == fault_granule) + if (fault_status == ESR_ELx_FSC_PERM && vma_pagesize == fault_granule) ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot); else ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize, @@ -1441,7 +1443,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) fault_ipa = kvm_vcpu_get_fault_ipa(vcpu); is_iabt = kvm_vcpu_trap_is_iabt(vcpu); - if (fault_status == FSC_FAULT) { + if (fault_status == ESR_ELx_FSC_FAULT) { /* Beyond sanitised PARange (which is the IPA limit) */ if (fault_ipa >= BIT_ULL(get_kvm_ipa_limit())) { kvm_inject_size_fault(vcpu); @@ -1476,8 +1478,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) kvm_vcpu_get_hfar(vcpu), fault_ipa); /* Check the stage-2 fault is trans. fault or write fault */ - if (fault_status != FSC_FAULT && fault_status != FSC_PERM && - fault_status != FSC_ACCESS) { + if (fault_status != ESR_ELx_FSC_FAULT && + fault_status != ESR_ELx_FSC_PERM && + fault_status != ESR_ELx_FSC_ACCESS) { kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n", kvm_vcpu_trap_get_class(vcpu), (unsigned long)kvm_vcpu_trap_get_fault(vcpu), @@ -1539,7 +1542,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) /* Userspace should not be able to register out-of-bounds IPAs */ VM_BUG_ON(fault_ipa >= kvm_phys_size(vcpu->kvm)); - if (fault_status == FSC_ACCESS) { + if (fault_status == ESR_ELx_FSC_ACCESS) { handle_access_fault(vcpu, fault_ipa); ret = 1; goto out_unlock; |