diff options
Diffstat (limited to 'arch/x86/kvm/mmu/tdp_mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 740 |
1 files changed, 422 insertions, 318 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 34207b874886..88f69a6cc492 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -27,6 +27,15 @@ void kvm_mmu_init_tdp_mmu(struct kvm *kvm) INIT_LIST_HEAD(&kvm->arch.tdp_mmu_pages); } +static __always_inline void kvm_lockdep_assert_mmu_lock_held(struct kvm *kvm, + bool shared) +{ + if (shared) + lockdep_assert_held_read(&kvm->mmu_lock); + else + lockdep_assert_held_write(&kvm->mmu_lock); +} + void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) { if (!kvm->arch.tdp_mmu_enabled) @@ -41,32 +50,85 @@ void kvm_mmu_uninit_tdp_mmu(struct kvm *kvm) rcu_barrier(); } -static void tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root) +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); + +static void tdp_mmu_free_sp(struct kvm_mmu_page *sp) { - if (kvm_mmu_put_root(kvm, root)) - kvm_tdp_mmu_free_root(kvm, root); + free_page((unsigned long)sp->spt); + kmem_cache_free(mmu_page_header_cache, sp); } -static inline bool tdp_mmu_next_root_valid(struct kvm *kvm, - struct kvm_mmu_page *root) +/* + * This is called through call_rcu in order to free TDP page table memory + * safely with respect to other kernel threads that may be operating on + * the memory. + * By only accessing TDP MMU page table memory in an RCU read critical + * section, and freeing it after a grace period, lockless access to that + * memory won't use it after it is freed. + */ +static void tdp_mmu_free_sp_rcu_callback(struct rcu_head *head) { - lockdep_assert_held_write(&kvm->mmu_lock); + struct kvm_mmu_page *sp = container_of(head, struct kvm_mmu_page, + rcu_head); - if (list_entry_is_head(root, &kvm->arch.tdp_mmu_roots, link)) - return false; + tdp_mmu_free_sp(sp); +} - kvm_mmu_get_root(kvm, root); - return true; +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)) + return; + + WARN_ON(!root->tdp_mmu_page); + + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + list_del_rcu(&root->link); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); + + zap_gfn_range(kvm, root, 0, max_gfn, false, false, shared); + + call_rcu(&root->rcu_head, tdp_mmu_free_sp_rcu_callback); } -static inline struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, - struct kvm_mmu_page *root) +/* + * Finds the next valid root after root (or the first valid root if root + * is NULL), takes a reference on it, and returns that next root. If root + * is not NULL, this thread should have already taken a reference on it, and + * that reference will be dropped. If no valid root is found, this + * function will return NULL. + */ +static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, + struct kvm_mmu_page *prev_root, + bool shared) { struct kvm_mmu_page *next_root; - next_root = list_next_entry(root, link); - tdp_mmu_put_root(kvm, root); + rcu_read_lock(); + + if (prev_root) + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, + &prev_root->link, + typeof(*prev_root), link); + else + next_root = list_first_or_null_rcu(&kvm->arch.tdp_mmu_roots, + typeof(*next_root), link); + + while (next_root && !kvm_tdp_mmu_get_root(kvm, next_root)) + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, + &next_root->link, typeof(*next_root), link); + + rcu_read_unlock(); + + if (prev_root) + kvm_tdp_mmu_put_root(kvm, prev_root, shared); + return next_root; } @@ -75,35 +137,24 @@ static inline struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, * This makes it safe to release the MMU lock and yield within the loop, but * if exiting the loop early, the caller must drop the reference to the most * recent root. (Unless keeping a live reference is desirable.) + * + * If shared is set, this function is operating under the MMU lock in read + * mode. In the unlikely event that this thread must free a root, the lock + * will be temporarily dropped and reacquired in write mode. */ -#define for_each_tdp_mmu_root_yield_safe(_kvm, _root) \ - for (_root = list_first_entry(&_kvm->arch.tdp_mmu_roots, \ - typeof(*_root), link); \ - tdp_mmu_next_root_valid(_kvm, _root); \ - _root = tdp_mmu_next_root(_kvm, _root)) - -#define for_each_tdp_mmu_root(_kvm, _root) \ - list_for_each_entry(_root, &_kvm->arch.tdp_mmu_roots, link) - -static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, - gfn_t start, gfn_t end, bool can_yield, bool flush); - -void kvm_tdp_mmu_free_root(struct kvm *kvm, struct kvm_mmu_page *root) -{ - gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT); - - lockdep_assert_held_write(&kvm->mmu_lock); - - WARN_ON(root->root_count); - WARN_ON(!root->tdp_mmu_page); - - list_del(&root->link); - - zap_gfn_range(kvm, root, 0, max_gfn, false, false); - - free_page((unsigned long)root->spt); - kmem_cache_free(mmu_page_header_cache, root); -} +#define for_each_tdp_mmu_root_yield_safe(_kvm, _root, _as_id, _shared) \ + for (_root = tdp_mmu_next_root(_kvm, NULL, _shared); \ + _root; \ + _root = tdp_mmu_next_root(_kvm, _root, _shared)) \ + if (kvm_mmu_page_as_id(_root) != _as_id) { \ + } else + +#define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ + list_for_each_entry_rcu(_root, &_kvm->arch.tdp_mmu_roots, link, \ + lockdep_is_held_type(&kvm->mmu_lock, 0) || \ + lockdep_is_held(&kvm->arch.tdp_mmu_pages_lock)) \ + if (kvm_mmu_page_as_id(_root) != _as_id) { \ + } else static union kvm_mmu_page_role page_role_for_level(struct kvm_vcpu *vcpu, int level) @@ -137,81 +188,46 @@ static struct kvm_mmu_page *alloc_tdp_mmu_page(struct kvm_vcpu *vcpu, gfn_t gfn, return sp; } -static struct kvm_mmu_page *get_tdp_mmu_vcpu_root(struct kvm_vcpu *vcpu) +hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu) { union kvm_mmu_page_role role; struct kvm *kvm = vcpu->kvm; struct kvm_mmu_page *root; - role = page_role_for_level(vcpu, vcpu->arch.mmu->shadow_root_level); + lockdep_assert_held_write(&kvm->mmu_lock); - write_lock(&kvm->mmu_lock); + role = page_role_for_level(vcpu, vcpu->arch.mmu->shadow_root_level); /* Check for an existing root before allocating a new one. */ - for_each_tdp_mmu_root(kvm, root) { - if (root->role.word == role.word) { - kvm_mmu_get_root(kvm, root); - write_unlock(&kvm->mmu_lock); - return root; - } + for_each_tdp_mmu_root(kvm, root, kvm_mmu_role_as_id(role)) { + if (root->role.word == role.word && + kvm_tdp_mmu_get_root(kvm, root)) + goto out; } root = alloc_tdp_mmu_page(vcpu, 0, vcpu->arch.mmu->shadow_root_level); - root->root_count = 1; - - list_add(&root->link, &kvm->arch.tdp_mmu_roots); - - write_unlock(&kvm->mmu_lock); - - return root; -} - -hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu) -{ - struct kvm_mmu_page *root; + refcount_set(&root->tdp_mmu_root_count, 1); - root = get_tdp_mmu_vcpu_root(vcpu); - if (!root) - return INVALID_PAGE; + spin_lock(&kvm->arch.tdp_mmu_pages_lock); + list_add_rcu(&root->link, &kvm->arch.tdp_mmu_roots); + spin_unlock(&kvm->arch.tdp_mmu_pages_lock); +out: return __pa(root->spt); } -static void tdp_mmu_free_sp(struct kvm_mmu_page *sp) -{ - free_page((unsigned long)sp->spt); - kmem_cache_free(mmu_page_header_cache, sp); -} - -/* - * This is called through call_rcu in order to free TDP page table memory - * safely with respect to other kernel threads that may be operating on - * the memory. - * By only accessing TDP MMU page table memory in an RCU read critical - * section, and freeing it after a grace period, lockless access to that - * memory won't use it after it is freed. - */ -static void tdp_mmu_free_sp_rcu_callback(struct rcu_head *head) -{ - struct kvm_mmu_page *sp = container_of(head, struct kvm_mmu_page, - rcu_head); - - tdp_mmu_free_sp(sp); -} - static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, u64 old_spte, u64 new_spte, int level, bool shared); static void handle_changed_spte_acc_track(u64 old_spte, u64 new_spte, int level) { - bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte); - if (!is_shadow_present_pte(old_spte) || !is_last_spte(old_spte, level)) return; if (is_accessed_spte(old_spte) && - (!is_accessed_spte(new_spte) || pfn_changed)) + (!is_shadow_present_pte(new_spte) || !is_accessed_spte(new_spte) || + spte_to_pfn(old_spte) != spte_to_pfn(new_spte))) kvm_set_pfn_accessed(spte_to_pfn(old_spte)); } @@ -455,7 +471,7 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, if (was_leaf && is_dirty_spte(old_spte) && - (!is_dirty_spte(new_spte) || pfn_changed)) + (!is_present || !is_dirty_spte(new_spte) || pfn_changed)) kvm_set_pfn_dirty(spte_to_pfn(old_spte)); /* @@ -479,8 +495,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, } /* - * tdp_mmu_set_spte_atomic - Set a TDP MMU SPTE atomically and handle the - * associated bookkeeping + * tdp_mmu_set_spte_atomic_no_dirty_log - Set a TDP MMU SPTE atomically + * and handle the associated bookkeeping, but do not mark the page dirty + * in KVM's dirty bitmaps. * * @kvm: kvm instance * @iter: a tdp_iter instance currently on the SPTE that should be set @@ -488,9 +505,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, * 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_set_spte_atomic(struct kvm *kvm, - struct tdp_iter *iter, - u64 new_spte) +static inline bool tdp_mmu_set_spte_atomic_no_dirty_log(struct kvm *kvm, + struct tdp_iter *iter, + u64 new_spte) { lockdep_assert_held_read(&kvm->mmu_lock); @@ -498,19 +515,32 @@ static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm, * Do not change removed SPTEs. Only the thread that froze the SPTE * may modify it. */ - if (iter->old_spte == REMOVED_SPTE) + if (is_removed_spte(iter->old_spte)) return false; if (cmpxchg64(rcu_dereference(iter->sptep), iter->old_spte, new_spte) != iter->old_spte) return false; - handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte, - new_spte, iter->level, true); + __handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte, + new_spte, iter->level, true); + handle_changed_spte_acc_track(iter->old_spte, new_spte, iter->level); return true; } +static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm, + struct tdp_iter *iter, + u64 new_spte) +{ + 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); + return true; +} + static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm, struct tdp_iter *iter) { @@ -569,7 +599,7 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, * should be used. If operating under the MMU lock in write mode, the * use of the removed SPTE should not be necessary. */ - WARN_ON(iter->old_spte == REMOVED_SPTE); + WARN_ON(is_removed_spte(iter->old_spte)); WRITE_ONCE(*rcu_dereference(iter->sptep), new_spte); @@ -634,7 +664,8 @@ static inline void tdp_mmu_set_spte_no_dirty_log(struct kvm *kvm, * Return false if a yield was not needed. */ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm, - struct tdp_iter *iter, bool flush) + struct tdp_iter *iter, bool flush, + bool shared) { /* Ensure forward progress has been made before yielding. */ if (iter->next_last_level_gfn == iter->yielded_gfn) @@ -646,7 +677,11 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm, if (flush) kvm_flush_remote_tlbs(kvm); - cond_resched_rwlock_write(&kvm->mmu_lock); + if (shared) + cond_resched_rwlock_read(&kvm->mmu_lock); + else + cond_resched_rwlock_write(&kvm->mmu_lock); + rcu_read_lock(); WARN_ON(iter->gfn > iter->next_last_level_gfn); @@ -664,24 +699,32 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm, * 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 can_yield is true, will release the MMU lock and reschedule if the * scheduler needs the CPU or there is contention on the MMU lock. If this * function cannot yield, it will not release the MMU lock or reschedule and * the caller must ensure it does not supply too large a GFN range, or the - * operation can cause a soft lockup. Note, in some use cases a flush may be - * required by prior actions. Ensure the pending flush is performed prior to - * yielding. + * operation can cause a soft lockup. + * + * 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 lock in write mode. */ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, - gfn_t start, gfn_t end, bool can_yield, bool flush) + gfn_t start, gfn_t end, bool can_yield, bool flush, + bool shared) { struct tdp_iter iter; + kvm_lockdep_assert_mmu_lock_held(kvm, shared); + rcu_read_lock(); tdp_root_for_each_pte(iter, root, start, end) { +retry: if (can_yield && - tdp_mmu_iter_cond_resched(kvm, &iter, flush)) { + tdp_mmu_iter_cond_resched(kvm, &iter, flush, shared)) { flush = false; continue; } @@ -699,8 +742,17 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, !is_last_spte(iter.old_spte, iter.level)) continue; - tdp_mmu_set_spte(kvm, &iter, 0); - flush = true; + if (!shared) { + tdp_mmu_set_spte(kvm, &iter, 0); + flush = true; + } else if (!tdp_mmu_zap_spte_atomic(kvm, &iter)) { + /* + * The iter must explicitly re-read the SPTE because + * the atomic cmpxchg failed. + */ + iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep)); + goto retry; + } } rcu_read_unlock(); @@ -712,15 +764,21 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, * 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, gfn_t start, gfn_t end, - bool can_yield) +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) { struct kvm_mmu_page *root; - bool flush = false; - for_each_tdp_mmu_root_yield_safe(kvm, root) - flush = zap_gfn_range(kvm, root, start, end, can_yield, flush); + for_each_tdp_mmu_root_yield_safe(kvm, root, as_id, shared) + flush = zap_gfn_range(kvm, root, start, end, can_yield, flush, + shared); return flush; } @@ -728,14 +786,116 @@ bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, gfn_t start, gfn_t end, void kvm_tdp_mmu_zap_all(struct kvm *kvm) { gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT); - bool flush; + 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); + + if (flush) + kvm_flush_remote_tlbs(kvm); +} + +static struct kvm_mmu_page *next_invalidated_root(struct kvm *kvm, + struct kvm_mmu_page *prev_root) +{ + struct kvm_mmu_page *next_root; + + if (prev_root) + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, + &prev_root->link, + typeof(*prev_root), link); + else + next_root = list_first_or_null_rcu(&kvm->arch.tdp_mmu_roots, + typeof(*next_root), link); + + while (next_root && !(next_root->role.invalid && + refcount_read(&next_root->tdp_mmu_root_count))) + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, + &next_root->link, + typeof(*next_root), link); + + return next_root; +} + +/* + * Since kvm_tdp_mmu_zap_all_fast has acquired a reference to each + * invalidated root, they will not be freed until this function drops the + * reference. Before dropping that reference, tear down the paging + * structure so that whichever thread does drop the last reference + * only has to do a trivial amount of work. Since the roots are invalid, + * no new SPTEs should be created under them. + */ +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; + + lockdep_assert_held_read(&kvm->mmu_lock); + + rcu_read_lock(); + + root = next_invalidated_root(kvm, NULL); + + while (root) { + next_root = next_invalidated_root(kvm, root); + + rcu_read_unlock(); + + flush = zap_gfn_range(kvm, root, 0, max_gfn, true, flush, + true); + + /* + * Put the reference acquired in + * kvm_tdp_mmu_invalidate_roots + */ + kvm_tdp_mmu_put_root(kvm, root, true); + + root = next_root; + + rcu_read_lock(); + } + + rcu_read_unlock(); - flush = kvm_tdp_mmu_zap_gfn_range(kvm, 0, max_gfn); if (flush) kvm_flush_remote_tlbs(kvm); } /* + * Mark each TDP MMU root as invalid so that other threads + * will drop their references and allow the root count to + * go to 0. + * + * Also take a reference on all roots so that this thread + * can do the bulk of the work required to free the roots + * once they are invalidated. Without this reference, a + * vCPU thread might drop the last reference to a root and + * get stuck with tearing down the entire paging structure. + * + * Roots which have a zero refcount should be skipped as + * they're already being torn down. + * Already invalid roots should be referenced again so that + * they aren't freed before kvm_tdp_mmu_zap_all_fast is + * done with them. + * + * This has essentially the same effect for the TDP MMU + * as updating mmu_valid_gen does for the shadow MMU. + */ +void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm) +{ + struct kvm_mmu_page *root; + + lockdep_assert_held_write(&kvm->mmu_lock); + list_for_each_entry(root, &kvm->arch.tdp_mmu_roots, link) + if (refcount_inc_not_zero(&root->tdp_mmu_root_count)) + root->role.invalid = true; +} + +/* * Installs a last-level SPTE to handle a TDP page fault. * (NPT/EPT violation/misconfiguration) */ @@ -777,12 +937,11 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, int write, trace_mark_mmio_spte(rcu_dereference(iter->sptep), iter->gfn, new_spte); ret = RET_PF_EMULATE; - } else + } else { trace_kvm_mmu_set_spte(iter->level, iter->gfn, rcu_dereference(iter->sptep)); + } - trace_kvm_mmu_set_spte(iter->level, iter->gfn, - rcu_dereference(iter->sptep)); if (!prefault) vcpu->stat.pf_fixed++; @@ -882,199 +1041,139 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, return ret; } -static __always_inline int -kvm_tdp_mmu_handle_hva_range(struct kvm *kvm, - unsigned long start, - unsigned long end, - unsigned long data, - int (*handler)(struct kvm *kvm, - struct kvm_memory_slot *slot, - struct kvm_mmu_page *root, - gfn_t start, - gfn_t end, - unsigned long data)) +bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range, + bool flush) { - struct kvm_memslots *slots; - struct kvm_memory_slot *memslot; struct kvm_mmu_page *root; - int ret = 0; - int as_id; - - for_each_tdp_mmu_root_yield_safe(kvm, root) { - as_id = kvm_mmu_page_as_id(root); - slots = __kvm_memslots(kvm, as_id); - kvm_for_each_memslot(memslot, slots) { - unsigned long hva_start, hva_end; - gfn_t gfn_start, gfn_end; - - hva_start = max(start, memslot->userspace_addr); - hva_end = min(end, memslot->userspace_addr + - (memslot->npages << PAGE_SHIFT)); - if (hva_start >= hva_end) - continue; - /* - * {gfn(page) | page intersects with [hva_start, hva_end)} = - * {gfn_start, gfn_start+1, ..., gfn_end-1}. - */ - gfn_start = hva_to_gfn_memslot(hva_start, memslot); - gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot); - ret |= handler(kvm, memslot, root, gfn_start, - gfn_end, data); - } - } + for_each_tdp_mmu_root(kvm, root, range->slot->as_id) + flush |= zap_gfn_range(kvm, root, range->start, range->end, + range->may_block, flush, false); - return ret; + return flush; } -static int zap_gfn_range_hva_wrapper(struct kvm *kvm, - struct kvm_memory_slot *slot, - struct kvm_mmu_page *root, gfn_t start, - gfn_t end, unsigned long unused) -{ - return zap_gfn_range(kvm, root, start, end, false, false); -} +typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range); -int kvm_tdp_mmu_zap_hva_range(struct kvm *kvm, unsigned long start, - unsigned long end) +static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm, + struct kvm_gfn_range *range, + tdp_handler_t handler) { - return kvm_tdp_mmu_handle_hva_range(kvm, start, end, 0, - zap_gfn_range_hva_wrapper); + struct kvm_mmu_page *root; + struct tdp_iter iter; + bool ret = false; + + rcu_read_lock(); + + /* + * Don't support rescheduling, none of the MMU notifiers that funnel + * into this helper allow blocking; it'd be dead, wasteful code. + */ + for_each_tdp_mmu_root(kvm, root, range->slot->as_id) { + tdp_root_for_each_leaf_pte(iter, root, range->start, range->end) + ret |= handler(kvm, &iter, range); + } + + rcu_read_unlock(); + + return ret; } /* * Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero * if any of the GFNs in the range have been accessed. */ -static int age_gfn_range(struct kvm *kvm, struct kvm_memory_slot *slot, - struct kvm_mmu_page *root, gfn_t start, gfn_t end, - unsigned long unused) +static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range) { - struct tdp_iter iter; - int young = 0; u64 new_spte = 0; - rcu_read_lock(); + /* If we have a non-accessed entry we don't need to change the pte. */ + if (!is_accessed_spte(iter->old_spte)) + return false; - tdp_root_for_each_leaf_pte(iter, root, start, end) { + new_spte = iter->old_spte; + + if (spte_ad_enabled(new_spte)) { + new_spte &= ~shadow_accessed_mask; + } else { /* - * If we have a non-accessed entry we don't need to change the - * pte. + * Capture the dirty status of the page, so that it doesn't get + * lost when the SPTE is marked for access tracking. */ - if (!is_accessed_spte(iter.old_spte)) - continue; - - new_spte = iter.old_spte; - - if (spte_ad_enabled(new_spte)) { - clear_bit((ffs(shadow_accessed_mask) - 1), - (unsigned long *)&new_spte); - } else { - /* - * Capture the dirty status of the page, so that it doesn't get - * lost when the SPTE is marked for access tracking. - */ - if (is_writable_pte(new_spte)) - kvm_set_pfn_dirty(spte_to_pfn(new_spte)); + if (is_writable_pte(new_spte)) + kvm_set_pfn_dirty(spte_to_pfn(new_spte)); - 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; - - trace_kvm_age_page(iter.gfn, iter.level, slot, young); + new_spte = mark_spte_for_access_track(new_spte); } - rcu_read_unlock(); + tdp_mmu_set_spte_no_acc_track(kvm, iter, new_spte); - return young; + return true; } -int kvm_tdp_mmu_age_hva_range(struct kvm *kvm, unsigned long start, - unsigned long end) +bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) { - return kvm_tdp_mmu_handle_hva_range(kvm, start, end, 0, - age_gfn_range); + return kvm_tdp_mmu_handle_gfn(kvm, range, age_gfn_range); } -static int test_age_gfn(struct kvm *kvm, struct kvm_memory_slot *slot, - struct kvm_mmu_page *root, gfn_t gfn, gfn_t unused, - unsigned long unused2) +static bool test_age_gfn(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range) { - struct tdp_iter iter; - - tdp_root_for_each_leaf_pte(iter, root, gfn, gfn + 1) - if (is_accessed_spte(iter.old_spte)) - return 1; - - return 0; + return is_accessed_spte(iter->old_spte); } -int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva) +bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { - return kvm_tdp_mmu_handle_hva_range(kvm, hva, hva + 1, 0, - test_age_gfn); + return kvm_tdp_mmu_handle_gfn(kvm, range, test_age_gfn); } -/* - * Handle the changed_pte MMU notifier for the TDP MMU. - * data is a pointer to the new pte_t mapping the HVA specified by the MMU - * notifier. - * Returns non-zero if a flush is needed before releasing the MMU lock. - */ -static int set_tdp_spte(struct kvm *kvm, struct kvm_memory_slot *slot, - struct kvm_mmu_page *root, gfn_t gfn, gfn_t unused, - unsigned long data) +static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter, + struct kvm_gfn_range *range) { - struct tdp_iter iter; - pte_t *ptep = (pte_t *)data; - kvm_pfn_t new_pfn; u64 new_spte; - int need_flush = 0; - - rcu_read_lock(); - WARN_ON(pte_huge(*ptep)); + /* Huge pages aren't expected to be modified without first being zapped. */ + WARN_ON(pte_huge(range->pte) || range->start + 1 != range->end); - new_pfn = pte_pfn(*ptep); - - tdp_root_for_each_pte(iter, root, gfn, gfn + 1) { - if (iter.level != PG_LEVEL_4K) - continue; - - if (!is_shadow_present_pte(iter.old_spte)) - break; - - tdp_mmu_set_spte(kvm, &iter, 0); - - kvm_flush_remote_tlbs_with_address(kvm, iter.gfn, 1); + if (iter->level != PG_LEVEL_4K || + !is_shadow_present_pte(iter->old_spte)) + return false; - if (!pte_write(*ptep)) { - new_spte = kvm_mmu_changed_pte_notifier_make_spte( - iter.old_spte, new_pfn); + /* + * Note, when changing a read-only SPTE, it's not strictly necessary to + * zero the SPTE before setting the new PFN, but doing so preserves the + * invariant that the PFN of a present * leaf SPTE can never change. + * See __handle_changed_spte(). + */ + tdp_mmu_set_spte(kvm, iter, 0); - tdp_mmu_set_spte(kvm, &iter, new_spte); - } + if (!pte_write(range->pte)) { + new_spte = kvm_mmu_changed_pte_notifier_make_spte(iter->old_spte, + pte_pfn(range->pte)); - need_flush = 1; + tdp_mmu_set_spte(kvm, iter, new_spte); } - if (need_flush) - kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); - - rcu_read_unlock(); - - return 0; + return true; } -int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address, - pte_t *host_ptep) +/* + * Handle the changed_pte MMU notifier for the TDP MMU. + * data is a pointer to the new pte_t mapping the HVA specified by the MMU + * notifier. + * Returns non-zero if a flush is needed before releasing the MMU lock. + */ +bool kvm_tdp_mmu_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { - return kvm_tdp_mmu_handle_hva_range(kvm, address, address + 1, - (unsigned long)host_ptep, - set_tdp_spte); + bool flush = kvm_tdp_mmu_handle_gfn(kvm, range, set_spte_gfn); + + /* FIXME: return 'flush' instead of flushing here. */ + if (flush) + kvm_flush_remote_tlbs_with_address(kvm, range->start, 1); + + return false; } /* @@ -1095,7 +1194,8 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, for_each_tdp_pte_min_level(iter, root->spt, root->role.level, min_level, start, end) { - if (tdp_mmu_iter_cond_resched(kvm, &iter, false)) +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) continue; if (!is_shadow_present_pte(iter.old_spte) || @@ -1105,7 +1205,15 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, new_spte = iter.old_spte & ~PT_WRITABLE_MASK; - tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); + if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, &iter, + new_spte)) { + /* + * The iter must explicitly re-read the SPTE because + * the atomic cmpxchg failed. + */ + iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep)); + goto retry; + } spte_set = true; } @@ -1122,17 +1230,13 @@ 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_yield_safe(kvm, root) { - root_as_id = kvm_mmu_page_as_id(root); - if (root_as_id != slot->as_id) - continue; + lockdep_assert_held_read(&kvm->mmu_lock); + for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) spte_set |= wrprot_gfn_range(kvm, root, slot->base_gfn, slot->base_gfn + slot->npages, min_level); - } return spte_set; } @@ -1154,7 +1258,8 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, rcu_read_lock(); tdp_root_for_each_leaf_pte(iter, root, start, end) { - if (tdp_mmu_iter_cond_resched(kvm, &iter, false)) +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) continue; if (spte_ad_need_write_protect(iter.old_spte)) { @@ -1169,7 +1274,15 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, continue; } - tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); + if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, &iter, + new_spte)) { + /* + * The iter must explicitly re-read the SPTE because + * the atomic cmpxchg failed. + */ + iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep)); + goto retry; + } spte_set = true; } @@ -1187,17 +1300,13 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, 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_yield_safe(kvm, root) { - root_as_id = kvm_mmu_page_as_id(root); - if (root_as_id != slot->as_id) - continue; + lockdep_assert_held_read(&kvm->mmu_lock); + for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) spte_set |= clear_dirty_gfn_range(kvm, root, slot->base_gfn, slot->base_gfn + slot->npages); - } return spte_set; } @@ -1259,37 +1368,32 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, bool wrprot) { struct kvm_mmu_page *root; - int root_as_id; lockdep_assert_held_write(&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; - + for_each_tdp_mmu_root(kvm, root, slot->as_id) clear_dirty_pt_masked(kvm, root, gfn, mask, wrprot); - } } /* * Clear leaf entries which could be replaced by large mappings, for * GFNs within the slot. */ -static void zap_collapsible_spte_range(struct kvm *kvm, +static bool zap_collapsible_spte_range(struct kvm *kvm, struct kvm_mmu_page *root, - struct kvm_memory_slot *slot) + const struct kvm_memory_slot *slot, + bool flush) { gfn_t start = slot->base_gfn; gfn_t end = start + slot->npages; struct tdp_iter iter; kvm_pfn_t pfn; - bool spte_set = false; rcu_read_lock(); tdp_root_for_each_pte(iter, root, start, end) { - if (tdp_mmu_iter_cond_resched(kvm, &iter, spte_set)) { - spte_set = false; +retry: + if (tdp_mmu_iter_cond_resched(kvm, &iter, flush, true)) { + flush = false; continue; } @@ -1303,38 +1407,43 @@ static void zap_collapsible_spte_range(struct kvm *kvm, pfn, PG_LEVEL_NUM)) continue; - tdp_mmu_set_spte(kvm, &iter, 0); - - spte_set = true; + if (!tdp_mmu_zap_spte_atomic(kvm, &iter)) { + /* + * The iter must explicitly re-read the SPTE because + * the atomic cmpxchg failed. + */ + iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep)); + goto retry; + } + flush = true; } rcu_read_unlock(); - if (spte_set) - kvm_flush_remote_tlbs(kvm); + + return flush; } /* * Clear non-leaf entries (and free associated page tables) which could * be replaced by large mappings, for GFNs within the slot. */ -void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, - struct kvm_memory_slot *slot) +bool kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot, + bool flush) { struct kvm_mmu_page *root; - int root_as_id; - for_each_tdp_mmu_root_yield_safe(kvm, root) { - root_as_id = kvm_mmu_page_as_id(root); - if (root_as_id != slot->as_id) - continue; + lockdep_assert_held_read(&kvm->mmu_lock); - zap_collapsible_spte_range(kvm, root, slot); - } + for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) + flush = zap_collapsible_spte_range(kvm, root, slot, flush); + + return flush; } /* * Removes write access on the last level SPTE mapping this GFN and unsets the - * SPTE_MMU_WRITABLE bit to ensure future writes continue to be intercepted. + * MMU-writable bit to ensure future writes continue to be intercepted. * Returns true if an SPTE was set and a TLB flush is needed. */ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root, @@ -1351,7 +1460,7 @@ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root, break; new_spte = iter.old_spte & - ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE); + ~(PT_WRITABLE_MASK | shadow_mmu_writable_mask); tdp_mmu_set_spte(kvm, &iter, new_spte); spte_set = true; @@ -1364,24 +1473,19 @@ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root, /* * Removes write access on the last level SPTE mapping this GFN and unsets the - * SPTE_MMU_WRITABLE bit to ensure future writes continue to be intercepted. + * MMU-writable bit to ensure future writes continue to be intercepted. * Returns true if an SPTE was set and a TLB flush is needed. */ bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn) { struct kvm_mmu_page *root; - int root_as_id; bool spte_set = false; lockdep_assert_held_write(&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; - + for_each_tdp_mmu_root(kvm, root, slot->as_id) spte_set |= write_protect_gfn(kvm, root, gfn); - } + return spte_set; } |