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)
}
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);
static void tdp_mmu_free_sp(struct kvm_mmu_page *sp)
{
tdp_mmu_free_sp(sp);
}
-void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root)
+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);
- lockdep_assert_held_write(&kvm->mmu_lock);
+ kvm_lockdep_assert_mmu_lock_held(kvm, shared);
if (!refcount_dec_and_test(&root->tdp_mmu_root_count))
return;
list_del_rcu(&root->link);
spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
- zap_gfn_range(kvm, root, 0, max_gfn, false, false);
+ zap_gfn_range(kvm, root, 0, max_gfn, false, false, shared);
call_rcu(&root->rcu_head, tdp_mmu_free_sp_rcu_callback);
}
* function will return NULL.
*/
static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm,
- struct kvm_mmu_page *prev_root)
+ struct kvm_mmu_page *prev_root,
+ bool shared)
{
struct kvm_mmu_page *next_root;
- lockdep_assert_held_write(&kvm->mmu_lock);
-
rcu_read_lock();
if (prev_root)
rcu_read_unlock();
if (prev_root)
- kvm_tdp_mmu_put_root(kvm, prev_root);
+ kvm_tdp_mmu_put_root(kvm, prev_root, shared);
return next_root;
}
* 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, _as_id) \
- for (_root = tdp_mmu_next_root(_kvm, NULL); \
- _root; \
- _root = tdp_mmu_next_root(_kvm, _root)) \
- if (kvm_mmu_page_as_id(_root) != _as_id) { \
+#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) \
* 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)
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);
* 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;
}
!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();
* 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)
+ gfn_t end, bool can_yield, bool flush,
+ bool shared)
{
struct kvm_mmu_page *root;
- for_each_tdp_mmu_root_yield_safe(kvm, root, as_id)
- 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;
}
int i;
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
- flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, max_gfn, flush);
+ flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, max_gfn,
+ flush, false);
if (flush)
kvm_flush_remote_tlbs(kvm);
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);
+ range->may_block, flush, false);
return flush;
}
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))
+ if (tdp_mmu_iter_cond_resched(kvm, &iter, false, false))
continue;
if (!is_shadow_present_pte(iter.old_spte) ||
struct kvm_mmu_page *root;
bool spte_set = false;
- for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id)
+ for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, false)
spte_set |= wrprot_gfn_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages, min_level);
rcu_read_lock();
tdp_root_for_each_leaf_pte(iter, root, start, end) {
- if (tdp_mmu_iter_cond_resched(kvm, &iter, false))
+ if (tdp_mmu_iter_cond_resched(kvm, &iter, false, false))
continue;
if (spte_ad_need_write_protect(iter.old_spte)) {
struct kvm_mmu_page *root;
bool spte_set = false;
- for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id)
+ for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, false)
spte_set |= clear_dirty_gfn_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages);
rcu_read_lock();
tdp_root_for_each_pte(iter, root, start, end) {
- if (tdp_mmu_iter_cond_resched(kvm, &iter, flush)) {
+ if (tdp_mmu_iter_cond_resched(kvm, &iter, flush, false)) {
flush = false;
continue;
}
{
struct kvm_mmu_page *root;
- for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id)
+ for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, false)
flush = zap_collapsible_spte_range(kvm, root, slot, flush);
return flush;