diff options
Diffstat (limited to 'arch/x86/kvm/mmu/tdp_mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 172 |
1 files changed, 114 insertions, 58 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 0853370bd811..64ccfc1fa553 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -10,7 +10,7 @@ #include <asm/cmpxchg.h> #include <trace/events/kvm.h> -static bool __read_mostly tdp_mmu_enabled = false; +static bool __read_mostly tdp_mmu_enabled = true; module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644); /* Initializes the TDP MMU for the VM, if enabled. */ @@ -43,6 +43,7 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) if (!kvm->arch.tdp_mmu_enabled) return; + WARN_ON(!list_empty(&kvm->arch.tdp_mmu_pages)); WARN_ON(!list_empty(&kvm->arch.tdp_mmu_roots)); /* @@ -81,8 +82,6 @@ static void tdp_mmu_free_sp_rcu_callback(struct rcu_head *head) void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root, bool shared) { - gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT); - kvm_lockdep_assert_mmu_lock_held(kvm, shared); if (!refcount_dec_and_test(&root->tdp_mmu_root_count)) @@ -94,7 +93,7 @@ void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root, list_del_rcu(&root->link); spin_unlock(&kvm->arch.tdp_mmu_pages_lock); - zap_gfn_range(kvm, root, 0, max_gfn, false, false, shared); + zap_gfn_range(kvm, root, 0, -1ull, false, false, shared); call_rcu(&root->rcu_head, tdp_mmu_free_sp_rcu_callback); } @@ -256,26 +255,17 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, * * @kvm: kvm instance * @sp: the new page - * @shared: This operation may not be running under the exclusive use of - * the MMU lock and the operation must synchronize with other - * threads that might be adding or removing pages. * @account_nx: This page replaces a NX large page and should be marked for * eventual reclaim. */ static void tdp_mmu_link_page(struct kvm *kvm, struct kvm_mmu_page *sp, - bool shared, bool account_nx) + bool account_nx) { - if (shared) - spin_lock(&kvm->arch.tdp_mmu_pages_lock); - else - lockdep_assert_held_write(&kvm->mmu_lock); - + spin_lock(&kvm->arch.tdp_mmu_pages_lock); list_add(&sp->link, &kvm->arch.tdp_mmu_pages); if (account_nx) account_huge_nx_page(kvm, sp); - - if (shared) - spin_unlock(&kvm->arch.tdp_mmu_pages_lock); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); } /** @@ -446,13 +436,6 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, trace_kvm_tdp_mmu_spte_changed(as_id, gfn, level, old_spte, new_spte); - if (is_large_pte(old_spte) != is_large_pte(new_spte)) { - if (is_large_pte(old_spte)) - atomic64_sub(1, (atomic64_t*)&kvm->stat.lpages); - else - atomic64_add(1, (atomic64_t*)&kvm->stat.lpages); - } - /* * The only times a SPTE should be changed from a non-present to * non-present state is when an MMIO entry is installed/modified/ @@ -478,6 +461,8 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, return; } + if (is_leaf != was_leaf) + kvm_update_page_stats(kvm, level, is_leaf ? 1 : -1); if (was_leaf && is_dirty_spte(old_spte) && (!is_present || !is_dirty_spte(new_spte) || pfn_changed)) @@ -527,6 +512,10 @@ static inline bool tdp_mmu_set_spte_atomic_no_dirty_log(struct kvm *kvm, if (is_removed_spte(iter->old_spte)) return false; + /* + * Note, fast_pf_fix_direct_spte() can also modify TDP MMU SPTEs and + * does not hold the mmu_lock. + */ if (cmpxchg64(rcu_dereference(iter->sptep), iter->old_spte, new_spte) != iter->old_spte) return false; @@ -538,15 +527,40 @@ static inline bool tdp_mmu_set_spte_atomic_no_dirty_log(struct kvm *kvm, return true; } -static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm, - struct tdp_iter *iter, - u64 new_spte) +/* + * tdp_mmu_map_set_spte_atomic - Set a leaf TDP MMU SPTE atomically to resolve a + * TDP page fault. + * + * @vcpu: The vcpu instance that took the TDP page fault. + * @iter: a tdp_iter instance currently on the SPTE that should be set + * @new_spte: The value the SPTE should be set to + * + * Returns: true if the SPTE was set, false if it was not. If false is returned, + * this function will have no side-effects. + */ +static inline bool tdp_mmu_map_set_spte_atomic(struct kvm_vcpu *vcpu, + struct tdp_iter *iter, + u64 new_spte) { + struct kvm *kvm = vcpu->kvm; + if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, iter, new_spte)) return false; - handle_changed_spte_dirty_log(kvm, iter->as_id, iter->gfn, - iter->old_spte, new_spte, iter->level); + /* + * Use kvm_vcpu_gfn_to_memslot() instead of going through + * handle_changed_spte_dirty_log() to leverage vcpu->last_used_slot. + */ + if (is_writable_pte(new_spte)) { + struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, iter->gfn); + + if (slot && kvm_slot_dirty_track_enabled(slot)) { + /* Enforced by kvm_mmu_hugepage_adjust. */ + WARN_ON_ONCE(iter->level > PG_LEVEL_4K); + mark_page_dirty_in_slot(kvm, slot, iter->gfn); + } + } + return true; } @@ -559,7 +573,7 @@ static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm, * immediately installing a present entry in its place * before the TLBs are flushed. */ - if (!tdp_mmu_set_spte_atomic(kvm, iter, REMOVED_SPTE)) + if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, iter, REMOVED_SPTE)) return false; kvm_flush_remote_tlbs_with_address(kvm, iter->gfn, @@ -724,13 +738,29 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, gfn_t start, gfn_t end, bool can_yield, bool flush, bool shared) { + gfn_t max_gfn_host = 1ULL << (shadow_phys_bits - PAGE_SHIFT); + bool zap_all = (start == 0 && end >= max_gfn_host); struct tdp_iter iter; + /* + * No need to try to step down in the iterator when zapping all SPTEs, + * zapping the top-level non-leaf SPTEs will recurse on their children. + */ + int min_level = zap_all ? root->role.level : PG_LEVEL_4K; + + /* + * Bound the walk at host.MAXPHYADDR, guest accesses beyond that will + * hit a #PF(RSVD) and never get to an EPT Violation/Misconfig / #NPF, + * and so KVM will never install a SPTE for such addresses. + */ + end = min(end, max_gfn_host); + kvm_lockdep_assert_mmu_lock_held(kvm, shared); rcu_read_lock(); - tdp_root_for_each_pte(iter, root, start, end) { + for_each_tdp_pte_min_level(iter, root->spt, root->role.level, + min_level, start, end) { retry: if (can_yield && tdp_mmu_iter_cond_resched(kvm, &iter, flush, shared)) { @@ -744,9 +774,10 @@ retry: /* * If this is a non-last-level SPTE that covers a larger range * than should be zapped, continue, and zap the mappings at a - * lower level. + * lower level, except when zapping all SPTEs. */ - if ((iter.gfn < start || + if (!zap_all && + (iter.gfn < start || iter.gfn + KVM_PAGES_PER_HPAGE(iter.level) > end) && !is_last_spte(iter.old_spte, iter.level)) continue; @@ -773,34 +804,26 @@ retry: * non-root pages mapping GFNs strictly within that range. Returns true if * SPTEs have been cleared and a TLB flush is needed before releasing the * MMU lock. - * - * If shared is true, this thread holds the MMU lock in read mode and must - * account for the possibility that other threads are modifying the paging - * structures concurrently. If shared is false, this thread should hold the - * MMU in write mode. */ bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start, - gfn_t end, bool can_yield, bool flush, - bool shared) + gfn_t end, bool can_yield, bool flush) { struct kvm_mmu_page *root; - for_each_tdp_mmu_root_yield_safe(kvm, root, as_id, shared) + for_each_tdp_mmu_root_yield_safe(kvm, root, as_id, false) flush = zap_gfn_range(kvm, root, start, end, can_yield, flush, - shared); + false); return flush; } void kvm_tdp_mmu_zap_all(struct kvm *kvm) { - gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT); bool flush = false; int i; for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) - flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, max_gfn, - flush, false); + flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, -1ull, flush); if (flush) kvm_flush_remote_tlbs(kvm); @@ -838,7 +861,6 @@ static struct kvm_mmu_page *next_invalidated_root(struct kvm *kvm, */ void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm) { - gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT); struct kvm_mmu_page *next_root; struct kvm_mmu_page *root; bool flush = false; @@ -854,8 +876,7 @@ void kvm_tdp_mmu_zap_invalidated_roots(struct kvm *kvm) rcu_read_unlock(); - flush = zap_gfn_range(kvm, root, 0, max_gfn, true, flush, - true); + flush = zap_gfn_range(kvm, root, 0, -1ull, true, flush, true); /* * Put the reference acquired in @@ -927,7 +948,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, int write, if (new_spte == iter->old_spte) ret = RET_PF_SPURIOUS; - else if (!tdp_mmu_set_spte_atomic(vcpu->kvm, iter, new_spte)) + else if (!tdp_mmu_map_set_spte_atomic(vcpu, iter, new_spte)) return RET_PF_RETRY; /* @@ -1031,9 +1052,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, new_spte = make_nonleaf_spte(child_pt, !shadow_accessed_mask); - if (tdp_mmu_set_spte_atomic(vcpu->kvm, &iter, - new_spte)) { - tdp_mmu_link_page(vcpu->kvm, sp, true, + if (tdp_mmu_set_spte_atomic_no_dirty_log(vcpu->kvm, &iter, new_spte)) { + tdp_mmu_link_page(vcpu->kvm, sp, huge_page_disallowed && req_level >= iter.level); @@ -1242,8 +1262,8 @@ retry: * 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) +bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, + const struct kvm_memory_slot *slot, int min_level) { struct kvm_mmu_page *root; bool spte_set = false; @@ -1313,7 +1333,8 @@ retry: * 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) +bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, + const struct kvm_memory_slot *slot) { struct kvm_mmu_page *root; bool spte_set = false; @@ -1516,6 +1537,8 @@ bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm, /* * Return the level of the lowest level SPTE added to sptes. * That SPTE may be non-present. + * + * Must be called between kvm_tdp_mmu_walk_lockless_{begin,end}. */ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) @@ -1527,14 +1550,47 @@ int kvm_tdp_mmu_get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, *root_level = vcpu->arch.mmu->shadow_root_level; - rcu_read_lock(); - tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) { leaf = iter.level; sptes[leaf] = iter.old_spte; } - rcu_read_unlock(); - return leaf; } + +/* + * Returns the last level spte pointer of the shadow page walk for the given + * gpa, and sets *spte to the spte value. This spte may be non-preset. If no + * walk could be performed, returns NULL and *spte does not contain valid data. + * + * Contract: + * - Must be called between kvm_tdp_mmu_walk_lockless_{begin,end}. + * - The returned sptep must not be used after kvm_tdp_mmu_walk_lockless_end. + * + * WARNING: This function is only intended to be called during fast_page_fault. + */ +u64 *kvm_tdp_mmu_fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, u64 addr, + u64 *spte) +{ + struct tdp_iter iter; + struct kvm_mmu *mmu = vcpu->arch.mmu; + gfn_t gfn = addr >> PAGE_SHIFT; + tdp_ptep_t sptep = NULL; + + tdp_mmu_for_each_pte(iter, mmu, gfn, gfn + 1) { + *spte = iter.old_spte; + sptep = iter.sptep; + } + + /* + * Perform the rcu_dereference to get the raw spte pointer value since + * we are passing it up to fast_page_fault, which is shared with the + * legacy MMU and thus does not retain the TDP MMU-specific __rcu + * annotation. + * + * This is safe since fast_page_fault obeys the contracts of this + * function as well as all TDP MMU contracts around modifying SPTEs + * outside of mmu_lock. + */ + return rcu_dereference(sptep); +} |