1 files changed, 143 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h
new file mode 100644
index 000000000000..364c5da6c499
--- /dev/null
+++ b/arch/x86/kvm/mmu/tdp_iter.h
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef __KVM_X86_MMU_TDP_ITER_H
+#define __KVM_X86_MMU_TDP_ITER_H
+
+#include <linux/kvm_host.h>
+
+#include "mmu.h"
+#include "spte.h"
+
+/*
+ * TDP MMU SPTEs are RCU protected to allow paging structures (non-leaf SPTEs)
+ * to be zapped while holding mmu_lock for read, and to allow TLB flushes to be
+ * batched without having to collect the list of zapped SPs.  Flows that can
+ * remove SPs must service pending TLB flushes prior to dropping RCU protection.
+ */
+static inline u64 kvm_tdp_mmu_read_spte(tdp_ptep_t sptep)
+{
+	return READ_ONCE(*rcu_dereference(sptep));
+}
+
+static inline u64 kvm_tdp_mmu_write_spte_atomic(tdp_ptep_t sptep, u64 new_spte)
+{
+	KVM_MMU_WARN_ON(is_ept_ve_possible(new_spte));
+	return xchg(rcu_dereference(sptep), new_spte);
+}
+
+static inline u64 tdp_mmu_clear_spte_bits_atomic(tdp_ptep_t sptep, u64 mask)
+{
+	atomic64_t *sptep_atomic = (atomic64_t *)rcu_dereference(sptep);
+
+	return (u64)atomic64_fetch_and(~mask, sptep_atomic);
+}
+
+static inline void __kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 new_spte)
+{
+	KVM_MMU_WARN_ON(is_ept_ve_possible(new_spte));
+	WRITE_ONCE(*rcu_dereference(sptep), new_spte);
+}
+
+/*
+ * SPTEs must be modified atomically if they are shadow-present, leaf SPTEs,
+ * and have volatile bits (bits that can be set outside of mmu_lock) that
+ * must not be clobbered.
+ */
+static inline bool kvm_tdp_mmu_spte_need_atomic_update(u64 old_spte, int level)
+{
+	return is_shadow_present_pte(old_spte) &&
+	       is_last_spte(old_spte, level) &&
+	       spte_needs_atomic_update(old_spte);
+}
+
+static inline u64 kvm_tdp_mmu_write_spte(tdp_ptep_t sptep, u64 old_spte,
+					 u64 new_spte, int level)
+{
+	if (kvm_tdp_mmu_spte_need_atomic_update(old_spte, level))
+		return kvm_tdp_mmu_write_spte_atomic(sptep, new_spte);
+
+	__kvm_tdp_mmu_write_spte(sptep, new_spte);
+	return old_spte;
+}
+
+static inline u64 tdp_mmu_clear_spte_bits(tdp_ptep_t sptep, u64 old_spte,
+					  u64 mask, int level)
+{
+	if (kvm_tdp_mmu_spte_need_atomic_update(old_spte, level))
+		return tdp_mmu_clear_spte_bits_atomic(sptep, mask);
+
+	__kvm_tdp_mmu_write_spte(sptep, old_spte & ~mask);
+	return old_spte;
+}
+
+/*
+ * A TDP iterator performs a pre-order walk over a TDP paging structure.
+ */
+struct tdp_iter {
+	/*
+	 * The iterator will traverse the paging structure towards the mapping
+	 * for this GFN.
+	 */
+	gfn_t next_last_level_gfn;
+	/*
+	 * The next_last_level_gfn at the time when the thread last
+	 * yielded. Only yielding when the next_last_level_gfn !=
+	 * yielded_gfn helps ensure forward progress.
+	 */
+	gfn_t yielded_gfn;
+	/* Pointers to the page tables traversed to reach the current SPTE */
+	tdp_ptep_t pt_path[PT64_ROOT_MAX_LEVEL];
+	/* A pointer to the current SPTE */
+	tdp_ptep_t sptep;
+	/* The lowest GFN (mask bits excluded) mapped by the current SPTE */
+	gfn_t gfn;
+	/* Mask applied to convert the GFN to the mapping GPA */
+	gfn_t gfn_bits;
+	/* The level of the root page given to the iterator */
+	int root_level;
+	/* The lowest level the iterator should traverse to */
+	int min_level;
+	/* The iterator's current level within the paging structure */
+	int level;
+	/* The address space ID, i.e. SMM vs. regular. */
+	int as_id;
+	/* A snapshot of the value at sptep */
+	u64 old_spte;
+	/*
+	 * Whether the iterator has a valid state. This will be false if the
+	 * iterator walks off the end of the paging structure.
+	 */
+	bool valid;
+	/*
+	 * True if KVM dropped mmu_lock and yielded in the middle of a walk, in
+	 * which case tdp_iter_next() needs to restart the walk at the root
+	 * level instead of advancing to the next entry.
+	 */
+	bool yielded;
+};
+
+/*
+ * Iterates over every SPTE mapping the GFN range [start, end) in a
+ * preorder traversal.
+ */
+#define for_each_tdp_pte_min_level(iter, kvm, root, min_level, start, end)		  \
+	for (tdp_iter_start(&iter, root, min_level, start, kvm_gfn_root_bits(kvm, root)); \
+	     iter.valid && iter.gfn < end;						  \
+	     tdp_iter_next(&iter))
+
+#define for_each_tdp_pte_min_level_all(iter, root, min_level)		\
+	for (tdp_iter_start(&iter, root, min_level, 0, 0);		\
+		iter.valid && iter.gfn < tdp_mmu_max_gfn_exclusive();	\
+		tdp_iter_next(&iter))
+
+#define for_each_tdp_pte(iter, kvm, root, start, end)				\
+	for_each_tdp_pte_min_level(iter, kvm, root, PG_LEVEL_4K, start, end)
+
+tdp_ptep_t spte_to_child_pt(u64 pte, int level);
+
+void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root,
+		    int min_level, gfn_t next_last_level_gfn, gfn_t gfn_bits);
+void tdp_iter_next(struct tdp_iter *iter);
+void tdp_iter_restart(struct tdp_iter *iter);
+
+#endif /* __KVM_X86_MMU_TDP_ITER_H */