diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 798ad65f4fee..8e5dad80b337 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8025,7 +8025,11 @@ The valid bits in cap.args[0] are: When this quirk is disabled, the reset value is 0x10000 (APIC_LVT_MASKED). - KVM_X86_QUIRK_CD_NW_CLEARED By default, KVM clears CR0.CD and CR0.NW. + KVM_X86_QUIRK_CD_NW_CLEARED By default, KVM clears CR0.CD and CR0.NW on + AMD CPUs to workaround buggy guest firmware + that runs in perpetuity with CR0.CD, i.e. + with caches in "no fill" mode. + When this quirk is disabled, KVM does not change the value of CR0.CD and CR0.NW. diff --git a/Documentation/virt/kvm/x86/errata.rst b/Documentation/virt/kvm/x86/errata.rst index 49a05f24747b..4116045a8744 100644 --- a/Documentation/virt/kvm/x86/errata.rst +++ b/Documentation/virt/kvm/x86/errata.rst @@ -48,3 +48,21 @@ have the same physical APIC ID, KVM will deliver events targeting that APIC ID only to the vCPU with the lowest vCPU ID. If KVM_X2APIC_API_USE_32BIT_IDS is not enabled, KVM follows x86 architecture when processing interrupts (all vCPUs matching the target APIC ID receive the interrupt). + +MTRRs +----- +KVM does not virtualize guest MTRR memory types. KVM emulates accesses to MTRR +MSRs, i.e. {RD,WR}MSR in the guest will behave as expected, but KVM does not +honor guest MTRRs when determining the effective memory type, and instead +treats all of guest memory as having Writeback (WB) MTRRs. + +CR0.CD +------ +KVM does not virtualize CR0.CD on Intel CPUs. Similar to MTRR MSRs, KVM +emulates CR0.CD accesses so that loads and stores from/to CR0 behave as +expected, but setting CR0.CD=1 has no impact on the cachaeability of guest +memory. + +Note, this erratum does not affect AMD CPUs, which fully virtualize CR0.CD in +hardware, i.e. put the CPU caches into "no fill" mode when CR0.CD=1, even when +running in the guest. \ No newline at end of file diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index d5101f52e76c..210408361e9a 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -160,7 +160,6 @@ #define KVM_MIN_FREE_MMU_PAGES 5 #define KVM_REFILL_PAGES 25 #define KVM_MAX_CPUID_ENTRIES 256 -#define KVM_NR_FIXED_MTRR_REGION 88 #define KVM_NR_VAR_MTRR 8 #define ASYNC_PF_PER_VCPU 64 @@ -605,18 +604,12 @@ enum { KVM_DEBUGREG_WONT_EXIT = 2, }; -struct kvm_mtrr_range { - u64 base; - u64 mask; - struct list_head node; -}; - struct kvm_mtrr { - struct kvm_mtrr_range var_ranges[KVM_NR_VAR_MTRR]; - mtrr_type fixed_ranges[KVM_NR_FIXED_MTRR_REGION]; + u64 var[KVM_NR_VAR_MTRR * 2]; + u64 fixed_64k; + u64 fixed_16k[2]; + u64 fixed_4k[8]; u64 deftype; - - struct list_head head; }; /* Hyper-V SynIC timer */ diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index f2e7e5c9b9ef..24ea7183d7b4 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -221,12 +221,7 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, return -(u32)fault & errcode; } -bool __kvm_mmu_honors_guest_mtrrs(bool vm_has_noncoherent_dma); - -static inline bool kvm_mmu_honors_guest_mtrrs(struct kvm *kvm) -{ - return __kvm_mmu_honors_guest_mtrrs(kvm_arch_has_noncoherent_dma(kvm)); -} +bool kvm_mmu_may_ignore_guest_pat(void); int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index d3b8e4fad924..ee13fc7b0e27 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4671,38 +4671,23 @@ out_unlock: } #endif -bool __kvm_mmu_honors_guest_mtrrs(bool vm_has_noncoherent_dma) +bool kvm_mmu_may_ignore_guest_pat(void) { /* - * If host MTRRs are ignored (shadow_memtype_mask is non-zero), and the - * VM has non-coherent DMA (DMA doesn't snoop CPU caches), KVM's ABI is - * to honor the memtype from the guest's MTRRs so that guest accesses - * to memory that is DMA'd aren't cached against the guest's wishes. - * - * Note, KVM may still ultimately ignore guest MTRRs for certain PFNs, - * e.g. KVM will force UC memtype for host MMIO. + * When EPT is enabled (shadow_memtype_mask is non-zero), the CPU does + * not support self-snoop (or is affected by an erratum), and the VM + * has non-coherent DMA (DMA doesn't snoop CPU caches), KVM's ABI is to + * honor the memtype from the guest's PAT so that guest accesses to + * memory that is DMA'd aren't cached against the guest's wishes. As a + * result, KVM _may_ ignore guest PAT, whereas without non-coherent DMA, + * KVM _always_ ignores or honors guest PAT, i.e. doesn't toggle SPTE + * bits in response to non-coherent device (un)registration. */ - return vm_has_noncoherent_dma && shadow_memtype_mask; + return !static_cpu_has(X86_FEATURE_SELFSNOOP) && shadow_memtype_mask; } int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - /* - * If the guest's MTRRs may be used to compute the "real" memtype, - * restrict the mapping level to ensure KVM uses a consistent memtype - * across the entire mapping. - */ - if (kvm_mmu_honors_guest_mtrrs(vcpu->kvm)) { - for ( ; fault->max_level > PG_LEVEL_4K; --fault->max_level) { - int page_num = KVM_PAGES_PER_HPAGE(fault->max_level); - gfn_t base = gfn_round_for_level(fault->gfn, - fault->max_level); - - if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) - break; - } - } - #ifdef CONFIG_X86_64 if (tdp_mmu_enabled) return kvm_tdp_mmu_page_fault(vcpu, fault); diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c index a67c28a56417..05490b9d8a43 100644 --- a/arch/x86/kvm/mtrr.c +++ b/arch/x86/kvm/mtrr.c @@ -19,33 +19,21 @@ #include #include "cpuid.h" -#include "mmu.h" -#define IA32_MTRR_DEF_TYPE_E (1ULL << 11) -#define IA32_MTRR_DEF_TYPE_FE (1ULL << 10) -#define IA32_MTRR_DEF_TYPE_TYPE_MASK (0xff) - -static bool is_mtrr_base_msr(unsigned int msr) +static u64 *find_mtrr(struct kvm_vcpu *vcpu, unsigned int msr) { - /* MTRR base MSRs use even numbers, masks use odd numbers. */ - return !(msr & 0x1); -} + int index; -static struct kvm_mtrr_range *var_mtrr_msr_to_range(struct kvm_vcpu *vcpu, - unsigned int msr) -{ - int index = (msr - MTRRphysBase_MSR(0)) / 2; - - return &vcpu->arch.mtrr_state.var_ranges[index]; -} - -static bool msr_mtrr_valid(unsigned msr) -{ switch (msr) { case MTRRphysBase_MSR(0) ... MTRRphysMask_MSR(KVM_NR_VAR_MTRR - 1): + index = msr - MTRRphysBase_MSR(0); + return &vcpu->arch.mtrr_state.var[index]; case MSR_MTRRfix64K_00000: + return &vcpu->arch.mtrr_state.fixed_64k; case MSR_MTRRfix16K_80000: case MSR_MTRRfix16K_A0000: + index = msr - MSR_MTRRfix16K_80000; + return &vcpu->arch.mtrr_state.fixed_16k[index]; case MSR_MTRRfix4K_C0000: case MSR_MTRRfix4K_C8000: case MSR_MTRRfix4K_D0000: @@ -54,10 +42,14 @@ static bool msr_mtrr_valid(unsigned msr) case MSR_MTRRfix4K_E8000: case MSR_MTRRfix4K_F0000: case MSR_MTRRfix4K_F8000: + index = msr - MSR_MTRRfix4K_C0000; + return &vcpu->arch.mtrr_state.fixed_4k[index]; case MSR_MTRRdefType: - return true; + return &vcpu->arch.mtrr_state.deftype; + default: + break; } - return false; + return NULL; } static bool valid_mtrr_type(unsigned t) @@ -70,9 +62,6 @@ static bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) int i; u64 mask; - if (!msr_mtrr_valid(msr)) - return false; - if (msr == MSR_MTRRdefType) { if (data & ~0xcff) return false; @@ -85,8 +74,9 @@ static bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) } /* variable MTRRs */ - WARN_ON(!(msr >= MTRRphysBase_MSR(0) && - msr <= MTRRphysMask_MSR(KVM_NR_VAR_MTRR - 1))); + if (WARN_ON_ONCE(!(msr >= MTRRphysBase_MSR(0) && + msr <= MTRRphysMask_MSR(KVM_NR_VAR_MTRR - 1)))) + return false; mask = kvm_vcpu_reserved_gpa_bits_raw(vcpu); if ((msr & 1) == 0) { @@ -94,309 +84,32 @@ static bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data) if (!valid_mtrr_type(data & 0xff)) return false; mask |= 0xf00; - } else + } else { /* MTRR mask */ mask |= 0x7ff; + } return (data & mask) == 0; } -static bool mtrr_is_enabled(struct kvm_mtrr *mtrr_state) -{ - return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_E); -} - -static bool fixed_mtrr_is_enabled(struct kvm_mtrr *mtrr_state) -{ - return !!(mtrr_state->deftype & IA32_MTRR_DEF_TYPE_FE); -} - -static u8 mtrr_default_type(struct kvm_mtrr *mtrr_state) -{ - return mtrr_state->deftype & IA32_MTRR_DEF_TYPE_TYPE_MASK; -} - -static u8 mtrr_disabled_type(struct kvm_vcpu *vcpu) -{ - /* - * Intel SDM 11.11.2.2: all MTRRs are disabled when - * IA32_MTRR_DEF_TYPE.E bit is cleared, and the UC - * memory type is applied to all of physical memory. - * - * However, virtual machines can be run with CPUID such that - * there are no MTRRs. In that case, the firmware will never - * enable MTRRs and it is obviously undesirable to run the - * guest entirely with UC memory and we use WB. - */ - if (guest_cpuid_has(vcpu, X86_FEATURE_MTRR)) - return MTRR_TYPE_UNCACHABLE; - else - return MTRR_TYPE_WRBACK; -} - -/* -* Three terms are used in the following code: -* - segment, it indicates the address segments covered by fixed MTRRs. -* - unit, it corresponds to the MSR entry in the segment. -* - range, a range is covered in one memory cache type. -*/ -struct fixed_mtrr_segment { - u64 start; - u64 end; - - int range_shift; - - /* the start position in kvm_mtrr.fixed_ranges[]. */ - int range_start; -}; - -static struct fixed_mtrr_segment fixed_seg_table[] = { - /* MSR_MTRRfix64K_00000, 1 unit. 64K fixed mtrr. */ - { - .start = 0x0, - .end = 0x80000, - .range_shift = 16, /* 64K */ - .range_start = 0, - }, - - /* - * MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000, 2 units, - * 16K fixed mtrr. - */ - { - .start = 0x80000, - .end = 0xc0000, - .range_shift = 14, /* 16K */ - .range_start = 8, - }, - - /* - * MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000, 8 units, - * 4K fixed mtrr. - */ - { - .start = 0xc0000, - .end = 0x100000, - .range_shift = 12, /* 12K */ - .range_start = 24, - } -}; - -/* - * The size of unit is covered in one MSR, one MSR entry contains - * 8 ranges so that unit size is always 8 * 2^range_shift. - */ -static u64 fixed_mtrr_seg_unit_size(int seg) -{ - return 8 << fixed_seg_table[seg].range_shift; -} - -static bool fixed_msr_to_seg_unit(u32 msr, int *seg, int *unit) -{ - switch (msr) { - case MSR_MTRRfix64K_00000: - *seg = 0; - *unit = 0; - break; - case MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000: - *seg = 1; - *unit = array_index_nospec( - msr - MSR_MTRRfix16K_80000, - MSR_MTRRfix16K_A0000 - MSR_MTRRfix16K_80000 + 1); - break; - case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000: - *seg = 2; - *unit = array_index_nospec( - msr - MSR_MTRRfix4K_C0000, - MSR_MTRRfix4K_F8000 - MSR_MTRRfix4K_C0000 + 1); - break; - default: - return false; - } - - return true; -} - -static void fixed_mtrr_seg_unit_range(int seg, int unit, u64 *start, u64 *end) -{ - struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg]; - u64 unit_size = fixed_mtrr_seg_unit_size(seg); - - *start = mtrr_seg->start + unit * unit_size; - *end = *start + unit_size; - WARN_ON(*end > mtrr_seg->end); -} - -static int fixed_mtrr_seg_unit_range_index(int seg, int unit) -{ - struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg]; - - WARN_ON(mtrr_seg->start + unit * fixed_mtrr_seg_unit_size(seg) - > mtrr_seg->end); - - /* each unit has 8 ranges. */ - return mtrr_seg->range_start + 8 * unit; -} - -static int fixed_mtrr_seg_end_range_index(int seg) -{ - struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg]; - int n; - - n = (mtrr_seg->end - mtrr_seg->start) >> mtrr_seg->range_shift; - return mtrr_seg->range_start + n - 1; -} - -static bool fixed_msr_to_range(u32 msr, u64 *start, u64 *end) -{ - int seg, unit; - - if (!fixed_msr_to_seg_unit(msr, &seg, &unit)) - return false; - - fixed_mtrr_seg_unit_range(seg, unit, start, end); - return true; -} - -static int fixed_msr_to_range_index(u32 msr) -{ - int seg, unit; - - if (!fixed_msr_to_seg_unit(msr, &seg, &unit)) - return -1; - - return fixed_mtrr_seg_unit_range_index(seg, unit); -} - -static int fixed_mtrr_addr_to_seg(u64 addr) -{ - struct fixed_mtrr_segment *mtrr_seg; - int seg, seg_num = ARRAY_SIZE(fixed_seg_table); - - for (seg = 0; seg < seg_num; seg++) { - mtrr_seg = &fixed_seg_table[seg]; - if (mtrr_seg->start <= addr && addr < mtrr_seg->end) - return seg; - } - - return -1; -} - -static int fixed_mtrr_addr_seg_to_range_index(u64 addr, int seg) -{ - struct fixed_mtrr_segment *mtrr_seg; - int index; - - mtrr_seg = &fixed_seg_table[seg]; - index = mtrr_seg->range_start; - index += (addr - mtrr_seg->start) >> mtrr_seg->range_shift; - return index; -} - -static u64 fixed_mtrr_range_end_addr(int seg, int index) -{ - struct fixed_mtrr_segment *mtrr_seg = &fixed_seg_table[seg]; - int pos = index - mtrr_seg->range_start; - - return mtrr_seg->start + ((pos + 1) << mtrr_seg->range_shift); -} - -static void var_mtrr_range(struct kvm_mtrr_range *range, u64 *start, u64 *end) -{ - u64 mask; - - *start = range->base & PAGE_MASK; - - mask = range->mask & PAGE_MASK; - - /* This cannot overflow because writing to the reserved bits of - * variable MTRRs causes a #GP. - */ - *end = (*start | ~mask) + 1; -} - -static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr) -{ - struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state; - gfn_t start, end; - - if (!kvm_mmu_honors_guest_mtrrs(vcpu->kvm)) - return; - - if (!mtrr_is_enabled(mtrr_state) && msr != MSR_MTRRdefType) - return; - - /* fixed MTRRs. */ - if (fixed_msr_to_range(msr, &start, &end)) { - if (!fixed_mtrr_is_enabled(mtrr_state)) - return; - } else if (msr == MSR_MTRRdefType) { - start = 0x0; - end = ~0ULL; - } else { - /* variable range MTRRs. */ - var_mtrr_range(var_mtrr_msr_to_range(vcpu, msr), &start, &end); - } - - kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end)); -} - -static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range) -{ - return (range->mask & (1 << 11)) != 0; -} - -static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data) -{ - struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state; - struct kvm_mtrr_range *tmp, *cur; - - cur = var_mtrr_msr_to_range(vcpu, msr); - - /* remove the entry if it's in the list. */ - if (var_mtrr_range_is_valid(cur)) - list_del(&cur->node); - - /* - * Set all illegal GPA bits in the mask, since those bits must - * implicitly be 0. The bits are then cleared when reading them. - */ - if (is_mtrr_base_msr(msr)) - cur->base = data; - else - cur->mask = data | kvm_vcpu_reserved_gpa_bits_raw(vcpu); - - /* add it to the list if it's enabled. */ - if (var_mtrr_range_is_valid(cur)) { - list_for_each_entry(tmp, &mtrr_state->head, node) - if (cur->base >= tmp->base) - break; - list_add_tail(&cur->node, &tmp->node); - } -} - int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data) { - int index; + u64 *mtrr; + + mtrr = find_mtrr(vcpu, msr); + if (!mtrr) + return 1; if (!kvm_mtrr_valid(vcpu, msr, data)) return 1; - index = fixed_msr_to_range_index(msr); - if (index >= 0) - *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index] = data; - else if (msr == MSR_MTRRdefType) - vcpu->arch.mtrr_state.deftype = data; - else - set_var_mtrr_msr(vcpu, msr, data); - - update_mtrr(vcpu, msr); + *mtrr = data; return 0; } int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) { - int index; + u64 *mtrr; /* MSR_MTRRcap is a readonly MSR. */ if (msr == MSR_MTRRcap) { @@ -410,311 +123,10 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) return 0; } - if (!msr_mtrr_valid(msr)) + mtrr = find_mtrr(vcpu, msr); + if (!mtrr) return 1; - index = fixed_msr_to_range_index(msr); - if (index >= 0) { - *pdata = *(u64 *)&vcpu->arch.mtrr_state.fixed_ranges[index]; - } else if (msr == MSR_MTRRdefType) { - *pdata = vcpu->arch.mtrr_state.deftype; - } else { - /* Variable MTRRs */ - if (is_mtrr_base_msr(msr)) - *pdata = var_mtrr_msr_to_range(vcpu, msr)->base; - else - *pdata = var_mtrr_msr_to_range(vcpu, msr)->mask; - - *pdata &= ~kvm_vcpu_reserved_gpa_bits_raw(vcpu); - } - + *pdata = *mtrr; return 0; } - -void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu) -{ - INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head); -} - -struct mtrr_iter { - /* input fields. */ - struct kvm_mtrr *mtrr_state; - u64 start; - u64 end; - - /* output fields. */ - int mem_type; - /* mtrr is completely disabled? */ - bool mtrr_disabled; - /* [start, end) is not fully covered in MTRRs? */ - bool partial_map; - - /* private fields. */ - union { - /* used for fixed MTRRs. */ - struct { - int index; - int seg; - }; - - /* used for var MTRRs. */ - struct { - struct kvm_mtrr_range *range; - /* max address has been covered in var MTRRs. */ - u64 start_max; - }; - }; - - bool fixed; -}; - -static bool mtrr_lookup_fixed_start(struct mtrr_iter *iter) -{ - int seg, index; - - if (!fixed_mtrr_is_enabled(iter->mtrr_state)) - return false; - - seg = fixed_mtrr_addr_to_seg(iter->start); - if (seg < 0) - return false; - - iter->fixed = true; - index = fixed_mtrr_addr_seg_to_range_index(iter->start, seg); - iter->index = index; - iter->seg = seg; - return true; -} - -static bool match_var_range(struct mtrr_iter *iter, - struct kvm_mtrr_range *range) -{ - u64 start, end; - - var_mtrr_range(range, &start, &end); - if (!(start >= iter->end || end <= iter->start)) { - iter->range = range; - - /* - * the function is called when we do kvm_mtrr.head walking. - * Range has the minimum base address which interleaves - * [looker->start_max, looker->end). - */ - iter->partial_map |= iter->start_max < start; - - /* update the max address has been covered. */ - iter->start_max = max(iter->start_max, end); - return true; - } - - return false; -} - -static void __mtrr_lookup_var_next(struct mtrr_iter *iter) -{ - struct kvm_mtrr *mtrr_state = iter->mtrr_state; - - list_for_each_entry_continue(iter->range, &mtrr_state->head, node) - if (match_var_range(iter, iter->range)) - return; - - iter->range = NULL; - iter->partial_map |= iter->start_max < iter->end; -} - -static void mtrr_lookup_var_start(struct mtrr_iter *iter) -{ - struct kvm_mtrr *mtrr_state = iter->mtrr_state; - - iter->fixed = false; - iter->start_max = iter->start; - iter->range = NULL; - iter->range = list_prepare_entry(iter->range, &mtrr_state->head, node); - - __mtrr_lookup_var_next(iter); -} - -static void mtrr_lookup_fixed_next(struct mtrr_iter *iter) -{ - /* terminate the lookup. */ - if (fixed_mtrr_range_end_addr(iter->seg, iter->index) >= iter->end) { - iter->fixed = false; - iter->range = NULL; - return; - } - - iter->index++; - - /* have looked up for all fixed MTRRs. */ - if (iter->index >= ARRAY_SIZE(iter->mtrr_state->fixed_ranges)) - return mtrr_lookup_var_start(iter); - - /* switch to next segment. */ - if (iter->index > fixed_mtrr_seg_end_range_index(iter->seg)) - iter->seg++; -} - -static void mtrr_lookup_var_next(struct mtrr_iter *iter) -{ - __mtrr_lookup_var_next(iter); -} - -static void mtrr_lookup_start(struct mtrr_iter *iter) -{ - if (!mtrr_is_enabled(iter->mtrr_state)) { - iter->mtrr_disabled = true; - return; - } - - if (!mtrr_lookup_fixed_start(iter)) - mtrr_lookup_var_start(iter); -} - -static void mtrr_lookup_init(struct mtrr_iter *iter, - struct kvm_mtrr *mtrr_state, u64 start, u64 end) -{ - iter->mtrr_state = mtrr_state; - iter->start = start; - iter->end = end; - iter->mtrr_disabled = false; - iter->partial_map = false; - iter->fixed = false; - iter->range = NULL; - - mtrr_lookup_start(iter); -} - -static bool mtrr_lookup_okay(struct mtrr_iter *iter) -{ - if (iter->fixed) { - iter->mem_type = iter->mtrr_state->fixed_ranges[iter->index]; - return true; - } - - if (iter->range) { - iter->mem_type = iter->range->base & 0xff; - return true; - } - - return false; -} - -static void mtrr_lookup_next(struct mtrr_iter *iter) -{ - if (iter->fixed) - mtrr_lookup_fixed_next(iter); - else - mtrr_lookup_var_next(iter); -} - -#define mtrr_for_each_mem_type(_iter_, _mtrr_, _gpa_start_, _gpa_end_) \ - for (mtrr_lookup_init(_iter_, _mtrr_, _gpa_start_, _gpa_end_); \ - mtrr_lookup_okay(_iter_); mtrr_lookup_next(_iter_)) - -u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn) -{ - struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state; - struct mtrr_iter iter; - u64 start, end; - int type = -1; - const int wt_wb_mask = (1 << MTRR_TYPE_WRBACK) - | (1 << MTRR_TYPE_WRTHROUGH); - - start = gfn_to_gpa(gfn); - end = start + PAGE_SIZE; - - mtrr_for_each_mem_type(&iter, mtrr_state, start, end) { - int curr_type = iter.mem_type; - - /* - * Please refer to Intel SDM Volume 3: 11.11.4.1 MTRR - * Precedences. - */ - - if (type == -1) { - type = curr_type; - continue; - } - - /* - * If two or more variable memory ranges match and the - * memory types are identical, then that memory type is - * used. - */ - if (type == curr_type) - continue; - - /* - * If two or more variable memory ranges match and one of - * the memory types is UC, the UC memory type used. - */ - if (curr_type == MTRR_TYPE_UNCACHABLE) - return MTRR_TYPE_UNCACHABLE; - - /* - * If two or more variable memory ranges match and the - * memory types are WT and WB, the WT memory type is used. - */ - if (((1 << type) & wt_wb_mask) && - ((1 << curr_type) & wt_wb_mask)) { - type = MTRR_TYPE_WRTHROUGH; - continue; - } - - /* - * For overlaps not defined by the above rules, processor - * behavior is undefined. - */ - - /* We use WB for this undefined behavior. :( */ - return MTRR_TYPE_WRBACK; - } - - if (iter.mtrr_disabled) - return mtrr_disabled_type(vcpu); - - /* not contained in any MTRRs. */ - if (type == -1) - return mtrr_default_type(mtrr_state); - - /* - * We just check one page, partially covered by MTRRs is - * impossible. - */ - WARN_ON(iter.partial_map); - - return type; -} -EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type); - -bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, - int page_num) -{ - struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state; - struct mtrr_iter iter; - u64 start, end; - int type = -1; - - start = gfn_to_gpa(gfn); - end = gfn_to_gpa(gfn + page_num); - mtrr_for_each_mem_type(&iter, mtrr_state, start, end) { - if (type == -1) { - type = iter.mem_type; - continue; - } - - if (type != iter.mem_type) - return false; - } - - if (iter.mtrr_disabled) - return true; - - if (!iter.partial_map) - return true; - - if (type == -1) - return true; - - return type == mtrr_default_type(mtrr_state); -} diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index bedb9ba96918..13a6b0281e37 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7670,39 +7670,25 @@ int vmx_vm_init(struct kvm *kvm) u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) { - /* We wanted to honor guest CD/MTRR/PAT, but doing so could result in - * memory aliases with conflicting memory types and sometimes MCEs. - * We have to be careful as to what are honored and when. - * - * For MMIO, guest CD/MTRR are ignored. The EPT memory type is set to - * UC. The effective memory type is UC or WC depending on guest PAT. - * This was historically the source of MCEs and we want to be - * conservative. - * - * When there is no need to deal with noncoherent DMA (e.g., no VT-d - * or VT-d has snoop control), guest CD/MTRR/PAT are all ignored. The - * EPT memory type is set to WB. The effective memory type is forced - * WB. - * - * Otherwise, we trust guest. Guest CD/MTRR/PAT are all honored. The - * EPT memory type is used to emulate guest CD/MTRR. + /* + * Force UC for host MMIO regions, as allowing the guest to access MMIO + * with cacheable accesses will result in Machine Checks. */ - if (is_mmio) return MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT; - if (!kvm_arch_has_noncoherent_dma(vcpu->kvm)) + /* + * Force WB and ignore guest PAT if the VM does NOT have a non-coherent + * device attached and the CPU doesn't support self-snoop. Letting the + * guest control memory types on Intel CPUs without self-snoop may + * result in unexpected behavior, and so KVM's (historical) ABI is to + * trust the guest to behave only as a last resort. + */ + if (!static_cpu_has(X86_FEATURE_SELFSNOOP) && + !kvm_arch_has_noncoherent_dma(vcpu->kvm)) return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT; - if (kvm_read_cr0_bits(vcpu, X86_CR0_CD)) { - if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED)) - return MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT; - else - return (MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT) | - VMX_EPT_IPAT_BIT; - } - - return kvm_mtrr_get_guest_memory_type(vcpu, gfn) << VMX_EPT_MT_EPTE_SHIFT; + return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT); } static void vmcs_set_secondary_exec_control(struct vcpu_vmx *vmx, u32 new_ctl) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e90e1a74564e..281edbbfc83d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -946,11 +946,6 @@ void kvm_post_set_cr0(struct kvm_vcpu *vcpu, unsigned long old_cr0, unsigned lon if ((cr0 ^ old_cr0) & KVM_MMU_CR0_ROLE_BITS) kvm_mmu_reset_context(vcpu); - - if (((cr0 ^ old_cr0) & X86_CR0_CD) && - kvm_mmu_honors_guest_mtrrs(vcpu->kvm) && - !kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED)) - kvm_zap_gfn_range(vcpu->kvm, 0, ~0ULL); } EXPORT_SYMBOL_GPL(kvm_post_set_cr0); @@ -11181,6 +11176,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_vcpu_srcu_read_lock(vcpu); + /* + * Call this to ensure WC buffers in guest are evicted after each VM + * Exit, so that the evicted WC writes can be snooped across all cpus + */ + smp_mb__after_srcu_read_lock(); + /* * Profile KVM exit RIPs: */ @@ -12264,7 +12265,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) vcpu->arch.arch_capabilities = kvm_get_arch_capabilities(); vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT; kvm_xen_init_vcpu(vcpu); - kvm_vcpu_mtrr_init(vcpu); vcpu_load(vcpu); kvm_set_tsc_khz(vcpu, vcpu->kvm->arch.default_tsc_khz); kvm_vcpu_reset(vcpu, false); @@ -13528,13 +13528,13 @@ EXPORT_SYMBOL_GPL(kvm_arch_has_assigned_device); static void kvm_noncoherent_dma_assignment_start_or_stop(struct kvm *kvm) { /* - * Non-coherent DMA assignment and de-assignment will affect - * whether KVM honors guest MTRRs and cause changes in memtypes - * in TDP. - * So, pass %true unconditionally to indicate non-coherent DMA was, - * or will be involved, and that zapping SPTEs might be necessary. + * Non-coherent DMA assignment and de-assignment may affect whether or + * not KVM honors guest PAT, and thus may cause changes in EPT SPTEs + * due to toggling the "ignore PAT" bit. Zap all SPTEs when the first + * (or last) non-coherent device is (un)registered to so that new SPTEs + * with the correct "ignore guest PAT" setting are created. */ - if (__kvm_mmu_honors_guest_mtrrs(true)) + if (kvm_mmu_may_ignore_guest_pat()) kvm_zap_gfn_range(kvm, gpa_to_gfn(0), gpa_to_gfn(~0ULL)); } diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index a88c65d3ea26..5da5b869a991 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -325,12 +325,8 @@ int handle_ud(struct kvm_vcpu *vcpu); void kvm_deliver_exception_payload(struct kvm_vcpu *vcpu, struct kvm_queued_exception *ex); -void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu); -u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn); int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data); int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata); -bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, - int page_num); bool kvm_vector_hashing_enabled(void); void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t gva, u16 error_code); int x86_decode_emulated_instruction(struct kvm_vcpu *vcpu, int emulation_type, diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 236610e4a8fa..1cb4527076de 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -343,6 +343,20 @@ static inline void smp_mb__after_srcu_read_unlock(void) /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ } +/** + * smp_mb__after_srcu_read_lock - ensure full ordering after srcu_read_lock + * + * Converts the preceding srcu_read_lock into a two-way memory barrier. + * + * Call this after srcu_read_lock, to guarantee that all memory operations + * that occur after smp_mb__after_srcu_read_lock will appear to happen after + * the preceding srcu_read_lock. + */ +static inline void smp_mb__after_srcu_read_lock(void) +{ + /* __srcu_read_lock has smp_mb() internally so nothing to do here. */ +} + DEFINE_LOCK_GUARD_1(srcu, struct srcu_struct, _T->idx = srcu_read_lock(_T->lock), srcu_read_unlock(_T->lock, _T->idx),