diff options
Diffstat (limited to 'arch/x86/kvm/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 155 |
1 files changed, 101 insertions, 54 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index cb8225969255..aafd399cf8c6 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -183,13 +183,13 @@ static u64 __read_mostly shadow_user_mask; static u64 __read_mostly shadow_accessed_mask; static u64 __read_mostly shadow_dirty_mask; static u64 __read_mostly shadow_mmio_mask; +static u64 __read_mostly shadow_mmio_value; static u64 __read_mostly shadow_present_mask; /* - * The mask/value to distinguish a PTE that has been marked not-present for - * access tracking purposes. - * The mask would be either 0 if access tracking is disabled, or - * SPTE_SPECIAL_MASK|VMX_EPT_RWX_MASK if access tracking is enabled. + * SPTEs used by MMUs without A/D bits are marked with shadow_acc_track_value. + * Non-present SPTEs with shadow_acc_track_value set are in place for access + * tracking. */ static u64 __read_mostly shadow_acc_track_mask; static const u64 shadow_acc_track_value = SPTE_SPECIAL_MASK; @@ -207,16 +207,40 @@ static const u64 shadow_acc_track_saved_bits_shift = PT64_SECOND_AVAIL_BITS_SHIF static void mmu_spte_set(u64 *sptep, u64 spte); static void mmu_free_roots(struct kvm_vcpu *vcpu); -void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask) +void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask, u64 mmio_value) { + BUG_ON((mmio_mask & mmio_value) != mmio_value); + shadow_mmio_value = mmio_value | SPTE_SPECIAL_MASK; shadow_mmio_mask = mmio_mask | SPTE_SPECIAL_MASK; } EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask); +static inline bool sp_ad_disabled(struct kvm_mmu_page *sp) +{ + return sp->role.ad_disabled; +} + +static inline bool spte_ad_enabled(u64 spte) +{ + MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value); + return !(spte & shadow_acc_track_value); +} + +static inline u64 spte_shadow_accessed_mask(u64 spte) +{ + MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value); + return spte_ad_enabled(spte) ? shadow_accessed_mask : 0; +} + +static inline u64 spte_shadow_dirty_mask(u64 spte) +{ + MMU_WARN_ON((spte & shadow_mmio_mask) == shadow_mmio_value); + return spte_ad_enabled(spte) ? shadow_dirty_mask : 0; +} + static inline bool is_access_track_spte(u64 spte) { - /* Always false if shadow_acc_track_mask is zero. */ - return (spte & shadow_acc_track_mask) == shadow_acc_track_value; + return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0; } /* @@ -270,7 +294,7 @@ static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, u64 mask = generation_mmio_spte_mask(gen); access &= ACC_WRITE_MASK | ACC_USER_MASK; - mask |= shadow_mmio_mask | access | gfn << PAGE_SHIFT; + mask |= shadow_mmio_value | access | gfn << PAGE_SHIFT; trace_mark_mmio_spte(sptep, gfn, access, gen); mmu_spte_set(sptep, mask); @@ -278,7 +302,7 @@ static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, static bool is_mmio_spte(u64 spte) { - return (spte & shadow_mmio_mask) == shadow_mmio_mask; + return (spte & shadow_mmio_mask) == shadow_mmio_value; } static gfn_t get_mmio_spte_gfn(u64 spte) @@ -315,12 +339,20 @@ static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) return likely(kvm_gen == spte_gen); } +/* + * Sets the shadow PTE masks used by the MMU. + * + * Assumptions: + * - Setting either @accessed_mask or @dirty_mask requires setting both + * - At least one of @accessed_mask or @acc_track_mask must be set + */ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, u64 dirty_mask, u64 nx_mask, u64 x_mask, u64 p_mask, u64 acc_track_mask) { - if (acc_track_mask != 0) - acc_track_mask |= SPTE_SPECIAL_MASK; + BUG_ON(!dirty_mask != !accessed_mask); + BUG_ON(!accessed_mask && !acc_track_mask); + BUG_ON(acc_track_mask & shadow_acc_track_value); shadow_user_mask = user_mask; shadow_accessed_mask = accessed_mask; @@ -329,7 +361,6 @@ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, shadow_x_mask = x_mask; shadow_present_mask = p_mask; shadow_acc_track_mask = acc_track_mask; - WARN_ON(shadow_accessed_mask != 0 && shadow_acc_track_mask != 0); } EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes); @@ -549,7 +580,7 @@ static bool spte_has_volatile_bits(u64 spte) is_access_track_spte(spte)) return true; - if (shadow_accessed_mask) { + if (spte_ad_enabled(spte)) { if ((spte & shadow_accessed_mask) == 0 || (is_writable_pte(spte) && (spte & shadow_dirty_mask) == 0)) return true; @@ -560,14 +591,17 @@ static bool spte_has_volatile_bits(u64 spte) static bool is_accessed_spte(u64 spte) { - return shadow_accessed_mask ? spte & shadow_accessed_mask - : !is_access_track_spte(spte); + u64 accessed_mask = spte_shadow_accessed_mask(spte); + + return accessed_mask ? spte & accessed_mask + : !is_access_track_spte(spte); } static bool is_dirty_spte(u64 spte) { - return shadow_dirty_mask ? spte & shadow_dirty_mask - : spte & PT_WRITABLE_MASK; + u64 dirty_mask = spte_shadow_dirty_mask(spte); + + return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; } /* Rules for using mmu_spte_set: @@ -707,10 +741,10 @@ static u64 mmu_spte_get_lockless(u64 *sptep) static u64 mark_spte_for_access_track(u64 spte) { - if (shadow_accessed_mask != 0) + if (spte_ad_enabled(spte)) return spte & ~shadow_accessed_mask; - if (shadow_acc_track_mask == 0 || is_access_track_spte(spte)) + if (is_access_track_spte(spte)) return spte; /* @@ -729,7 +763,6 @@ static u64 mark_spte_for_access_track(u64 spte) spte |= (spte & shadow_acc_track_saved_bits_mask) << shadow_acc_track_saved_bits_shift; spte &= ~shadow_acc_track_mask; - spte |= shadow_acc_track_value; return spte; } @@ -741,6 +774,7 @@ static u64 restore_acc_track_spte(u64 spte) u64 saved_bits = (spte >> shadow_acc_track_saved_bits_shift) & shadow_acc_track_saved_bits_mask; + WARN_ON_ONCE(spte_ad_enabled(spte)); WARN_ON_ONCE(!is_access_track_spte(spte)); new_spte &= ~shadow_acc_track_mask; @@ -759,7 +793,7 @@ static bool mmu_spte_age(u64 *sptep) if (!is_accessed_spte(spte)) return false; - if (shadow_accessed_mask) { + if (spte_ad_enabled(spte)) { clear_bit((ffs(shadow_accessed_mask) - 1), (unsigned long *)sptep); } else { @@ -1390,6 +1424,22 @@ static bool spte_clear_dirty(u64 *sptep) return mmu_spte_update(sptep, spte); } +static bool wrprot_ad_disabled_spte(u64 *sptep) +{ + bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, + (unsigned long *)sptep); + if (was_writable) + kvm_set_pfn_dirty(spte_to_pfn(*sptep)); + + return was_writable; +} + +/* + * Gets the GFN ready for another round of dirty logging by clearing the + * - D bit on ad-enabled SPTEs, and + * - W bit on ad-disabled SPTEs. + * Returns true iff any D or W bits were cleared. + */ static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head) { u64 *sptep; @@ -1397,7 +1447,10 @@ static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head) bool flush = false; for_each_rmap_spte(rmap_head, &iter, sptep) - flush |= spte_clear_dirty(sptep); + if (spte_ad_enabled(*sptep)) + flush |= spte_clear_dirty(sptep); + else + flush |= wrprot_ad_disabled_spte(sptep); return flush; } @@ -1420,7 +1473,8 @@ static bool __rmap_set_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head) bool flush = false; for_each_rmap_spte(rmap_head, &iter, sptep) - flush |= spte_set_dirty(sptep); + if (spte_ad_enabled(*sptep)) + flush |= spte_set_dirty(sptep); return flush; } @@ -1452,7 +1506,8 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, } /** - * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages + * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write + * protect the page if the D-bit isn't supported. * @kvm: kvm instance * @slot: slot to clear D-bit * @gfn_offset: start of the BITS_PER_LONG pages we care about @@ -1766,18 +1821,9 @@ static int kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, u64 *sptep; struct rmap_iterator iter; - /* - * If there's no access bit in the secondary pte set by the hardware and - * fast access tracking is also not enabled, it's up to gup-fast/gup to - * set the access bit in the primary pte or in the page structure. - */ - if (!shadow_accessed_mask && !shadow_acc_track_mask) - goto out; - for_each_rmap_spte(rmap_head, &iter, sptep) if (is_accessed_spte(*sptep)) return 1; -out: return 0; } @@ -1798,18 +1844,6 @@ static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end) { - /* - * In case of absence of EPT Access and Dirty Bits supports, - * emulate the accessed bit for EPT, by checking if this page has - * an EPT mapping, and clearing it if it does. On the next access, - * a new EPT mapping will be established. - * This has some overhead, but not as much as the cost of swapping - * out actively used pages or breaking up actively used hugepages. - */ - if (!shadow_accessed_mask && !shadow_acc_track_mask) - return kvm_handle_hva_range(kvm, start, end, 0, - kvm_unmap_rmapp); - return kvm_handle_hva_range(kvm, start, end, 0, kvm_age_rmapp); } @@ -2398,7 +2432,12 @@ static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); spte = __pa(sp->spt) | shadow_present_mask | PT_WRITABLE_MASK | - shadow_user_mask | shadow_x_mask | shadow_accessed_mask; + shadow_user_mask | shadow_x_mask; + + if (sp_ad_disabled(sp)) + spte |= shadow_acc_track_value; + else + spte |= shadow_accessed_mask; mmu_spte_set(sptep, spte); @@ -2666,10 +2705,15 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, { u64 spte = 0; int ret = 0; + struct kvm_mmu_page *sp; if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access)) return 0; + sp = page_header(__pa(sptep)); + if (sp_ad_disabled(sp)) + spte |= shadow_acc_track_value; + /* * For the EPT case, shadow_present_mask is 0 if hardware * supports exec-only page table entries. In that case, @@ -2678,7 +2722,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, */ spte |= shadow_present_mask; if (!speculative) - spte |= shadow_accessed_mask; + spte |= spte_shadow_accessed_mask(spte); if (pte_access & ACC_EXEC_MASK) spte |= shadow_x_mask; @@ -2735,7 +2779,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, if (pte_access & ACC_WRITE_MASK) { kvm_vcpu_mark_page_dirty(vcpu, gfn); - spte |= shadow_dirty_mask; + spte |= spte_shadow_dirty_mask(spte); } if (speculative) @@ -2877,16 +2921,16 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) { struct kvm_mmu_page *sp; + sp = page_header(__pa(sptep)); + /* - * Since it's no accessed bit on EPT, it's no way to - * distinguish between actually accessed translations - * and prefetched, so disable pte prefetch if EPT is - * enabled. + * Without accessed bits, there's no way to distinguish between + * actually accessed translations and prefetched, so disable pte + * prefetch if accessed bits aren't available. */ - if (!shadow_accessed_mask) + if (sp_ad_disabled(sp)) return; - sp = page_header(__pa(sptep)); if (sp->role.level > PT_PAGE_TABLE_LEVEL) return; @@ -4290,6 +4334,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) context->base_role.word = 0; context->base_role.smm = is_smm(vcpu); + context->base_role.ad_disabled = (shadow_accessed_mask == 0); context->page_fault = tdp_page_fault; context->sync_page = nonpaging_sync_page; context->invlpg = nonpaging_invlpg; @@ -4377,6 +4422,7 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, context->root_level = context->shadow_root_level; context->root_hpa = INVALID_PAGE; context->direct_map = false; + context->base_role.ad_disabled = !accessed_dirty; update_permission_bitmask(vcpu, context, true); update_pkru_bitmask(vcpu, context, true); @@ -4636,6 +4682,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, mask.smep_andnot_wp = 1; mask.smap_andnot_wp = 1; mask.smm = 1; + mask.ad_disabled = 1; /* * If we don't have indirect shadow pages, it means no page is |