From: Ben Gardon <bgardon@xxxxxxxxxx> Dirty logging is a key feature of the KVM MMU and must be supported by the TDP MMU. Add support for both the write protection and PML dirty logging modes. Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell machine. This series introduced no new failures. This series can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538 Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx> Message-Id: <20201014182700.2888246-16-bgardon@xxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> --- arch/x86/kvm/mmu/mmu.c | 14 ++ arch/x86/kvm/mmu/tdp_iter.h | 7 +- arch/x86/kvm/mmu/tdp_mmu.c | 299 +++++++++++++++++++++++++++++++++++- arch/x86/kvm/mmu/tdp_mmu.h | 10 ++ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 6 +- 6 files changed, 328 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 41f0354c7489..0c64643819b9 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1223,6 +1223,9 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, { struct kvm_rmap_head *rmap_head; + if (kvm->arch.tdp_mmu_enabled) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, true); while (mask) { rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PG_LEVEL_4K, slot); @@ -1249,6 +1252,9 @@ void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, { struct kvm_rmap_head *rmap_head; + if (kvm->arch.tdp_mmu_enabled) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, false); while (mask) { rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PG_LEVEL_4K, slot); @@ -5473,6 +5479,8 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, spin_lock(&kvm->mmu_lock); flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect, start_level, KVM_MAX_HUGEPAGE_LEVEL, false); + if (kvm->arch.tdp_mmu_enabled) + flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, PG_LEVEL_4K); spin_unlock(&kvm->mmu_lock); /* @@ -5561,6 +5569,8 @@ void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, spin_lock(&kvm->mmu_lock); flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, false); + if (kvm->arch.tdp_mmu_enabled) + flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot); spin_unlock(&kvm->mmu_lock); /* @@ -5582,6 +5592,8 @@ void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm, spin_lock(&kvm->mmu_lock); flush = slot_handle_large_level(kvm, memslot, slot_rmap_write_protect, false); + if (kvm->arch.tdp_mmu_enabled) + flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, PG_LEVEL_2M); spin_unlock(&kvm->mmu_lock); if (flush) @@ -5596,6 +5608,8 @@ void kvm_mmu_slot_set_dirty(struct kvm *kvm, spin_lock(&kvm->mmu_lock); flush = slot_handle_all_level(kvm, memslot, __rmap_set_dirty, false); + if (kvm->arch.tdp_mmu_enabled) + flush |= kvm_tdp_mmu_slot_set_dirty(kvm, memslot); spin_unlock(&kvm->mmu_lock); if (flush) diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h index 884ed2c70bfe..47170d0dc98e 100644 --- a/arch/x86/kvm/mmu/tdp_iter.h +++ b/arch/x86/kvm/mmu/tdp_iter.h @@ -41,11 +41,14 @@ struct tdp_iter { * Iterates over every SPTE mapping the GFN range [start, end) in a * preorder traversal. */ -#define for_each_tdp_pte(iter, root, root_level, start, end) \ - for (tdp_iter_start(&iter, root, root_level, PG_LEVEL_4K, start); \ +#define for_each_tdp_pte_min_level(iter, root, root_level, min_level, start, end) \ + for (tdp_iter_start(&iter, root, root_level, min_level, start); \ iter.valid && iter.gfn < end; \ tdp_iter_next(&iter)) +#define for_each_tdp_pte(iter, root, root_level, start, end) \ + for_each_tdp_pte_min_level(iter, root, root_level, PG_LEVEL_4K, start, end) + u64 *spte_to_child_pt(u64 pte, int level); void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level, diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 64e640cfcff9..7181b4ab54d0 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -161,6 +161,24 @@ static void handle_changed_spte_acc_track(u64 old_spte, u64 new_spte, int level) kvm_set_pfn_accessed(spte_to_pfn(old_spte)); } +static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, + u64 old_spte, u64 new_spte, int level) +{ + bool pfn_changed; + struct kvm_memory_slot *slot; + + if (level > PG_LEVEL_4K) + return; + + pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte); + + if ((!is_writable_pte(old_spte) || pfn_changed) && + is_writable_pte(new_spte)) { + slot = __gfn_to_memslot(__kvm_memslots(kvm, as_id), gfn); + mark_page_dirty_in_slot(slot, gfn); + } +} + /** * handle_changed_spte - handle bookkeeping associated with an SPTE change * @kvm: kvm instance @@ -273,10 +291,13 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, { __handle_changed_spte(kvm, as_id, gfn, old_spte, new_spte, level); handle_changed_spte_acc_track(old_spte, new_spte, level); + handle_changed_spte_dirty_log(kvm, as_id, gfn, old_spte, + new_spte, level); } static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, - u64 new_spte, bool record_acc_track) + u64 new_spte, bool record_acc_track, + bool record_dirty_log) { u64 *root_pt = tdp_iter_root_pt(iter); struct kvm_mmu_page *root = sptep_to_sp(root_pt); @@ -289,19 +310,30 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, if (record_acc_track) handle_changed_spte_acc_track(iter->old_spte, new_spte, iter->level); + if (record_dirty_log) + handle_changed_spte_dirty_log(kvm, as_id, iter->gfn, + iter->old_spte, new_spte, + iter->level); } static inline void tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, u64 new_spte) { - __tdp_mmu_set_spte(kvm, iter, new_spte, true); + __tdp_mmu_set_spte(kvm, iter, new_spte, true, true); } static inline void tdp_mmu_set_spte_no_acc_track(struct kvm *kvm, struct tdp_iter *iter, u64 new_spte) { - __tdp_mmu_set_spte(kvm, iter, new_spte, false); + __tdp_mmu_set_spte(kvm, iter, new_spte, false, true); +} + +static inline void tdp_mmu_set_spte_no_dirty_log(struct kvm *kvm, + struct tdp_iter *iter, + u64 new_spte) +{ + __tdp_mmu_set_spte(kvm, iter, new_spte, true, false); } #define tdp_root_for_each_pte(_iter, _root, _start, _end) \ @@ -334,6 +366,14 @@ static bool tdp_mmu_iter_flush_cond_resched(struct kvm *kvm, struct tdp_iter *it } } +static void tdp_mmu_iter_cond_resched(struct kvm *kvm, struct tdp_iter *iter) +{ + if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { + cond_resched_lock(&kvm->mmu_lock); + tdp_iter_refresh_walk(iter); + } +} + /* * Tears down the mappings for the range of gfns, [start, end), and frees the * non-root pages mapping GFNs strictly within that range. Returns true if @@ -638,6 +678,7 @@ static int age_gfn_range(struct kvm *kvm, struct kvm_memory_slot *slot, new_spte = mark_spte_for_access_track(new_spte); } + new_spte &= ~shadow_dirty_mask; tdp_mmu_set_spte_no_acc_track(kvm, &iter, new_spte); young = 1; @@ -727,3 +768,255 @@ int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address, set_tdp_spte); } +/* + * Remove write access from all the SPTEs mapping GFNs [start, end). If + * skip_4k is set, SPTEs that map 4k pages, will not be write-protected. + * Returns true if an SPTE has been changed and the TLBs need to be flushed. + */ +static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end, int min_level) +{ + struct tdp_iter iter; + u64 new_spte; + bool spte_set = false; + + BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL); + + for_each_tdp_pte_min_level(iter, root->spt, root->role.level, + min_level, start, end) { + if (!is_shadow_present_pte(iter.old_spte) || + !is_last_spte(iter.old_spte, iter.level)) + continue; + + new_spte = iter.old_spte & ~PT_WRITABLE_MASK; + + tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); + spte_set = true; + + tdp_mmu_iter_cond_resched(kvm, &iter); + } + return spte_set; +} + +/* + * Remove write access from all the SPTEs mapping GFNs in the memslot. Will + * only affect leaf SPTEs down to min_level. + * Returns true if an SPTE has been changed and the TLBs need to be flushed. + */ +bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, struct kvm_memory_slot *slot, + int min_level) +{ + struct kvm_mmu_page *root; + int root_as_id; + bool spte_set = false; + + for_each_tdp_mmu_root(kvm, root) { + root_as_id = kvm_mmu_page_as_id(root); + if (root_as_id != slot->as_id) + continue; + + /* + * Take a reference on the root so that it cannot be freed if + * this thread releases the MMU lock and yields in this loop. + */ + kvm_mmu_get_root(kvm, root); + + spte_set |= wrprot_gfn_range(kvm, root, slot->base_gfn, + slot->base_gfn + slot->npages, min_level); + + kvm_mmu_put_root(kvm, root); + } + + return spte_set; +} + +/* + * Clear the dirty status of all the SPTEs mapping GFNs in the memslot. If + * AD bits are enabled, this will involve clearing the dirty bit on each SPTE. + * If AD bits are not enabled, this will require clearing the writable bit on + * each SPTE. Returns true if an SPTE has been changed and the TLBs need to + * be flushed. + */ +static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end) +{ + struct tdp_iter iter; + u64 new_spte; + bool spte_set = false; + + tdp_root_for_each_leaf_pte(iter, root, start, end) { + if (spte_ad_need_write_protect(iter.old_spte)) { + if (is_writable_pte(iter.old_spte)) + new_spte = iter.old_spte & ~PT_WRITABLE_MASK; + else + continue; + } else { + if (iter.old_spte & shadow_dirty_mask) + new_spte = iter.old_spte & ~shadow_dirty_mask; + else + continue; + } + + tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); + spte_set = true; + + tdp_mmu_iter_cond_resched(kvm, &iter); + } + return spte_set; +} + +/* + * Clear the dirty status of all the SPTEs mapping GFNs in the memslot. If + * AD bits are enabled, this will involve clearing the dirty bit on each SPTE. + * If AD bits are not enabled, this will require clearing the writable bit on + * each SPTE. Returns true if an SPTE has been changed and the TLBs need to + * be flushed. + */ +bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, struct kvm_memory_slot *slot) +{ + struct kvm_mmu_page *root; + int root_as_id; + bool spte_set = false; + + for_each_tdp_mmu_root(kvm, root) { + root_as_id = kvm_mmu_page_as_id(root); + if (root_as_id != slot->as_id) + continue; + + /* + * Take a reference on the root so that it cannot be freed if + * this thread releases the MMU lock and yields in this loop. + */ + kvm_mmu_get_root(kvm, root); + + spte_set |= clear_dirty_gfn_range(kvm, root, slot->base_gfn, + slot->base_gfn + slot->npages); + + kvm_mmu_put_root(kvm, root); + } + + return spte_set; +} + +/* + * Clears the dirty status of all the 4k SPTEs mapping GFNs for which a bit is + * set in mask, starting at gfn. The given memslot is expected to contain all + * the GFNs represented by set bits in the mask. If AD bits are enabled, + * clearing the dirty status will involve clearing the dirty bit on each SPTE + * or, if AD bits are not enabled, clearing the writable bit on each SPTE. + */ +static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t gfn, unsigned long mask, bool wrprot) +{ + struct tdp_iter iter; + u64 new_spte; + + tdp_root_for_each_leaf_pte(iter, root, gfn + __ffs(mask), + gfn + BITS_PER_LONG) { + if (!mask) + break; + + if (iter.level > PG_LEVEL_4K || + !(mask & (1UL << (iter.gfn - gfn)))) + continue; + + if (wrprot || spte_ad_need_write_protect(iter.old_spte)) { + if (is_writable_pte(iter.old_spte)) + new_spte = iter.old_spte & ~PT_WRITABLE_MASK; + else + continue; + } else { + if (iter.old_spte & shadow_dirty_mask) + new_spte = iter.old_spte & ~shadow_dirty_mask; + else + continue; + } + + tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); + + mask &= ~(1UL << (iter.gfn - gfn)); + } +} + +/* + * Clears the dirty status of all the 4k SPTEs mapping GFNs for which a bit is + * set in mask, starting at gfn. The given memslot is expected to contain all + * the GFNs represented by set bits in the mask. If AD bits are enabled, + * clearing the dirty status will involve clearing the dirty bit on each SPTE + * or, if AD bits are not enabled, clearing the writable bit on each SPTE. + */ +void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn, unsigned long mask, + bool wrprot) +{ + struct kvm_mmu_page *root; + int root_as_id; + + lockdep_assert_held(&kvm->mmu_lock); + for_each_tdp_mmu_root(kvm, root) { + root_as_id = kvm_mmu_page_as_id(root); + if (root_as_id != slot->as_id) + continue; + + clear_dirty_pt_masked(kvm, root, gfn, mask, wrprot); + } +} + +/* + * Set the dirty status of all the SPTEs mapping GFNs in the memslot. This is + * only used for PML, and so will involve setting the dirty bit on each SPTE. + * Returns true if an SPTE has been changed and the TLBs need to be flushed. + */ +static bool set_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, + gfn_t start, gfn_t end) +{ + struct tdp_iter iter; + u64 new_spte; + bool spte_set = false; + + tdp_root_for_each_pte(iter, root, start, end) { + if (!is_shadow_present_pte(iter.old_spte)) + continue; + + new_spte = iter.old_spte | shadow_dirty_mask; + + tdp_mmu_set_spte(kvm, &iter, new_spte); + spte_set = true; + + tdp_mmu_iter_cond_resched(kvm, &iter); + } + + return spte_set; +} + +/* + * Set the dirty status of all the SPTEs mapping GFNs in the memslot. This is + * only used for PML, and so will involve setting the dirty bit on each SPTE. + * Returns true if an SPTE has been changed and the TLBs need to be flushed. + */ +bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot) +{ + struct kvm_mmu_page *root; + int root_as_id; + bool spte_set = false; + + for_each_tdp_mmu_root(kvm, root) { + root_as_id = kvm_mmu_page_as_id(root); + if (root_as_id != slot->as_id) + continue; + + /* + * Take a reference on the root so that it cannot be freed if + * this thread releases the MMU lock and yields in this loop. + */ + kvm_mmu_get_root(kvm, root); + + spte_set |= set_dirty_gfn_range(kvm, root, slot->base_gfn, + slot->base_gfn + slot->npages); + + kvm_mmu_put_root(kvm, root); + } + return spte_set; +} + diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index aeee3ce7b3f4..ece66f10d85f 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -28,4 +28,14 @@ int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva); int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address, pte_t *host_ptep); + +bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, struct kvm_memory_slot *slot, + int min_level); +bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, + struct kvm_memory_slot *slot); +void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn, unsigned long mask, + bool wrprot); +bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot); #endif /* __KVM_X86_MMU_TDP_MMU_H */ diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index c6f45687ba89..7f2e2a09ebbd 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -798,6 +798,7 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn); bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn); bool kvm_vcpu_is_visible_gfn(struct kvm_vcpu *vcpu, gfn_t gfn); unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn); +void mark_page_dirty_in_slot(struct kvm_memory_slot *memslot, gfn_t gfn); void mark_page_dirty(struct kvm *kvm, gfn_t gfn); struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 2e8539213125..2541a17ff1c4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -143,8 +143,6 @@ static void hardware_disable_all(void); static void kvm_io_bus_destroy(struct kvm_io_bus *bus); -static void mark_page_dirty_in_slot(struct kvm_memory_slot *memslot, gfn_t gfn); - __visible bool kvm_rebooting; EXPORT_SYMBOL_GPL(kvm_rebooting); @@ -2645,8 +2643,7 @@ int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len) } EXPORT_SYMBOL_GPL(kvm_clear_guest); -static void mark_page_dirty_in_slot(struct kvm_memory_slot *memslot, - gfn_t gfn) +void mark_page_dirty_in_slot(struct kvm_memory_slot *memslot, gfn_t gfn) { if (memslot && memslot->dirty_bitmap) { unsigned long rel_gfn = gfn - memslot->base_gfn; @@ -2654,6 +2651,7 @@ static void mark_page_dirty_in_slot(struct kvm_memory_slot *memslot, set_bit_le(rel_gfn, memslot->dirty_bitmap); } } +EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot); void mark_page_dirty(struct kvm *kvm, gfn_t gfn) { -- 2.26.2
