[PATCH 01/10] KVM: x86: MMU: Encapsulate the type of rmap-chain head in a new struct

[Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>]

New struct kvm_rmap_head makes the code type-safe to some extent.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
---
 arch/x86/include/asm/kvm_host.h |   8 +-
 arch/x86/kvm/mmu.c              | 196 ++++++++++++++++++++--------------------
 arch/x86/kvm/mmu_audit.c        |  13 +--
 3 files changed, 113 insertions(+), 104 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f608e17..8140077 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -214,6 +214,10 @@ union kvm_mmu_page_role {
 	};
 };
 
+struct kvm_rmap_head {
+	unsigned long val;
+};
+
 struct kvm_mmu_page {
 	struct list_head link;
 	struct hlist_node hash_link;
@@ -231,7 +235,7 @@ struct kvm_mmu_page {
 	bool unsync;
 	int root_count;          /* Currently serving as active root */
 	unsigned int unsync_children;
-	unsigned long parent_ptes;	/* Reverse mapping for parent_pte */
+	struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
 
 	/* The page is obsolete if mmu_valid_gen != kvm->arch.mmu_valid_gen.  */
 	unsigned long mmu_valid_gen;
@@ -606,7 +610,7 @@ struct kvm_lpage_info {
 };
 
 struct kvm_arch_memory_slot {
-	unsigned long *rmap[KVM_NR_PAGE_SIZES];
+	struct kvm_rmap_head *rmap[KVM_NR_PAGE_SIZES];
 	struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1];
 };
 
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 276d2f2..d9a6801 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -909,36 +909,35 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn,
 }
 
 /*
- * Pte mapping structures:
+ * About rmap_head encoding:
  *
- * If pte_list bit zero is zero, then pte_list point to the spte.
- *
- * If pte_list bit zero is one, (then pte_list & ~1) points to a struct
+ * If the bit zero of rmap_head->val is clear, then it points to the only spte
+ * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct
  * pte_list_desc containing more mappings.
- *
- * Returns the number of pte entries before the spte was added or zero if
- * the spte was not added.
- *
+ */
+
+/*
+ * Returns the number of pointers in the rmap chain, not counting the new one.
  */
 static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
-			unsigned long *pte_list)
+			struct kvm_rmap_head *rmap_head)
 {
 	struct pte_list_desc *desc;
 	int i, count = 0;
 
-	if (!*pte_list) {
+	if (!rmap_head->val) {
 		rmap_printk("pte_list_add: %p %llx 0->1\n", spte, *spte);
-		*pte_list = (unsigned long)spte;
-	} else if (!(*pte_list & 1)) {
+		rmap_head->val = (unsigned long)spte;
+	} else if (!(rmap_head->val & 1)) {
 		rmap_printk("pte_list_add: %p %llx 1->many\n", spte, *spte);
 		desc = mmu_alloc_pte_list_desc(vcpu);
-		desc->sptes[0] = (u64 *)*pte_list;
+		desc->sptes[0] = (u64 *)rmap_head->val;
 		desc->sptes[1] = spte;
-		*pte_list = (unsigned long)desc | 1;
+		rmap_head->val = (unsigned long)desc | 1;
 		++count;
 	} else {
 		rmap_printk("pte_list_add: %p %llx many->many\n", spte, *spte);
-		desc = (struct pte_list_desc *)(*pte_list & ~1ul);
+		desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
 		while (desc->sptes[PTE_LIST_EXT-1] && desc->more) {
 			desc = desc->more;
 			count += PTE_LIST_EXT;
@@ -955,8 +954,9 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
 }
 
 static void
-pte_list_desc_remove_entry(unsigned long *pte_list, struct pte_list_desc *desc,
-			   int i, struct pte_list_desc *prev_desc)
+pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head,
+			   struct pte_list_desc *desc, int i,
+			   struct pte_list_desc *prev_desc)
 {
 	int j;
 
@@ -967,43 +967,43 @@ pte_list_desc_remove_entry(unsigned long *pte_list, struct pte_list_desc *desc,
 	if (j != 0)
 		return;
 	if (!prev_desc && !desc->more)
-		*pte_list = (unsigned long)desc->sptes[0];
+		rmap_head->val = (unsigned long)desc->sptes[0];
 	else
 		if (prev_desc)
 			prev_desc->more = desc->more;
 		else
-			*pte_list = (unsigned long)desc->more | 1;
+			rmap_head->val = (unsigned long)desc->more | 1;
 	mmu_free_pte_list_desc(desc);
 }
 
-static void pte_list_remove(u64 *spte, unsigned long *pte_list)
+static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head)
 {
 	struct pte_list_desc *desc;
 	struct pte_list_desc *prev_desc;
 	int i;
 
-	if (!*pte_list) {
+	if (!rmap_head->val) {
 		printk(KERN_ERR "pte_list_remove: %p 0->BUG\n", spte);
 		BUG();
-	} else if (!(*pte_list & 1)) {
+	} else if (!(rmap_head->val & 1)) {
 		rmap_printk("pte_list_remove:  %p 1->0\n", spte);
-		if ((u64 *)*pte_list != spte) {
+		if ((u64 *)rmap_head->val != spte) {
 			printk(KERN_ERR "pte_list_remove:  %p 1->BUG\n", spte);
 			BUG();
 		}
-		*pte_list = 0;
+		rmap_head->val = 0;
 	} else {
 		rmap_printk("pte_list_remove:  %p many->many\n", spte);
-		desc = (struct pte_list_desc *)(*pte_list & ~1ul);
+		desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
 		prev_desc = NULL;
 		while (desc) {
-			for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
+			for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i) {
 				if (desc->sptes[i] == spte) {
-					pte_list_desc_remove_entry(pte_list,
-							       desc, i,
-							       prev_desc);
+					pte_list_desc_remove_entry(rmap_head,
+							desc, i, prev_desc);
 					return;
 				}
+			}
 			prev_desc = desc;
 			desc = desc->more;
 		}
@@ -1013,18 +1013,18 @@ static void pte_list_remove(u64 *spte, unsigned long *pte_list)
 }
 
 typedef void (*pte_list_walk_fn) (u64 *spte);
-static void pte_list_walk(unsigned long *pte_list, pte_list_walk_fn fn)
+static void pte_list_walk(struct kvm_rmap_head *rmap_head, pte_list_walk_fn fn)
 {
 	struct pte_list_desc *desc;
 	int i;
 
-	if (!*pte_list)
+	if (!rmap_head->val)
 		return;
 
-	if (!(*pte_list & 1))
-		return fn((u64 *)*pte_list);
+	if (!(rmap_head->val & 1))
+		return fn((u64 *)rmap_head->val);
 
-	desc = (struct pte_list_desc *)(*pte_list & ~1ul);
+	desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
 	while (desc) {
 		for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
 			fn(desc->sptes[i]);
@@ -1032,8 +1032,8 @@ static void pte_list_walk(unsigned long *pte_list, pte_list_walk_fn fn)
 	}
 }
 
-static unsigned long *__gfn_to_rmap(gfn_t gfn, int level,
-				    struct kvm_memory_slot *slot)
+static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level,
+					   struct kvm_memory_slot *slot)
 {
 	unsigned long idx;
 
@@ -1041,10 +1041,8 @@ static unsigned long *__gfn_to_rmap(gfn_t gfn, int level,
 	return &slot->arch.rmap[level - PT_PAGE_TABLE_LEVEL][idx];
 }
 
-/*
- * Take gfn and return the reverse mapping to it.
- */
-static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, struct kvm_mmu_page *sp)
+static struct kvm_rmap_head *gfn_to_rmap(struct kvm *kvm, gfn_t gfn,
+					 struct kvm_mmu_page *sp)
 {
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *slot;
@@ -1065,24 +1063,24 @@ static bool rmap_can_add(struct kvm_vcpu *vcpu)
 static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 {
 	struct kvm_mmu_page *sp;
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 
 	sp = page_header(__pa(spte));
 	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
-	rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp);
-	return pte_list_add(vcpu, spte, rmapp);
+	rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
+	return pte_list_add(vcpu, spte, rmap_head);
 }
 
 static void rmap_remove(struct kvm *kvm, u64 *spte)
 {
 	struct kvm_mmu_page *sp;
 	gfn_t gfn;
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 
 	sp = page_header(__pa(spte));
 	gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
-	rmapp = gfn_to_rmap(kvm, gfn, sp);
-	pte_list_remove(spte, rmapp);
+	rmap_head = gfn_to_rmap(kvm, gfn, sp);
+	pte_list_remove(spte, rmap_head);
 }
 
 /*
@@ -1102,17 +1100,18 @@ struct rmap_iterator {
  *
  * Returns sptep if found, NULL otherwise.
  */
-static u64 *rmap_get_first(unsigned long rmap, struct rmap_iterator *iter)
+static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head,
+			   struct rmap_iterator *iter)
 {
-	if (!rmap)
+	if (!rmap_head->val)
 		return NULL;
 
-	if (!(rmap & 1)) {
+	if (!(rmap_head->val & 1)) {
 		iter->desc = NULL;
-		return (u64 *)rmap;
+		return (u64 *)rmap_head->val;
 	}
 
-	iter->desc = (struct pte_list_desc *)(rmap & ~1ul);
+	iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
 	iter->pos = 0;
 	return iter->desc->sptes[iter->pos];
 }
@@ -1146,10 +1145,10 @@ static u64 *rmap_get_next(struct rmap_iterator *iter)
 	return NULL;
 }
 
-#define for_each_rmap_spte(_rmap_, _iter_, _spte_)			    \
-	   for (_spte_ = rmap_get_first(*_rmap_, _iter_);		    \
-		_spte_ && ({BUG_ON(!is_shadow_present_pte(*_spte_)); 1;});  \
-			_spte_ = rmap_get_next(_iter_))
+#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_)			\
+	for (_spte_ = rmap_get_first(_rmap_head_, _iter_);		\
+	     _spte_ && ({BUG_ON(!is_shadow_present_pte(*_spte_)); 1;});	\
+	     _spte_ = rmap_get_next(_iter_))
 
 static void drop_spte(struct kvm *kvm, u64 *sptep)
 {
@@ -1207,14 +1206,15 @@ static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool pt_protect)
 	return mmu_spte_update(sptep, spte);
 }
 
-static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp,
+static bool __rmap_write_protect(struct kvm *kvm,
+				 struct kvm_rmap_head *rmap_head,
 				 bool pt_protect)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
 	bool flush = false;
 
-	for_each_rmap_spte(rmapp, &iter, sptep)
+	for_each_rmap_spte(rmap_head, &iter, sptep)
 		flush |= spte_write_protect(kvm, sptep, pt_protect);
 
 	return flush;
@@ -1231,13 +1231,13 @@ static bool spte_clear_dirty(struct kvm *kvm, u64 *sptep)
 	return mmu_spte_update(sptep, spte);
 }
 
-static bool __rmap_clear_dirty(struct kvm *kvm, unsigned long *rmapp)
+static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
 	bool flush = false;
 
-	for_each_rmap_spte(rmapp, &iter, sptep)
+	for_each_rmap_spte(rmap_head, &iter, sptep)
 		flush |= spte_clear_dirty(kvm, sptep);
 
 	return flush;
@@ -1254,13 +1254,13 @@ static bool spte_set_dirty(struct kvm *kvm, u64 *sptep)
 	return mmu_spte_update(sptep, spte);
 }
 
-static bool __rmap_set_dirty(struct kvm *kvm, unsigned long *rmapp)
+static bool __rmap_set_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
 	bool flush = false;
 
-	for_each_rmap_spte(rmapp, &iter, sptep)
+	for_each_rmap_spte(rmap_head, &iter, sptep)
 		flush |= spte_set_dirty(kvm, sptep);
 
 	return flush;
@@ -1280,12 +1280,12 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
 				     struct kvm_memory_slot *slot,
 				     gfn_t gfn_offset, unsigned long mask)
 {
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 
 	while (mask) {
-		rmapp = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
-				      PT_PAGE_TABLE_LEVEL, slot);
-		__rmap_write_protect(kvm, rmapp, false);
+		rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
+					  PT_PAGE_TABLE_LEVEL, slot);
+		__rmap_write_protect(kvm, rmap_head, false);
 
 		/* clear the first set bit */
 		mask &= mask - 1;
@@ -1305,12 +1305,12 @@ void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm,
 				     struct kvm_memory_slot *slot,
 				     gfn_t gfn_offset, unsigned long mask)
 {
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 
 	while (mask) {
-		rmapp = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
-				      PT_PAGE_TABLE_LEVEL, slot);
-		__rmap_clear_dirty(kvm, rmapp);
+		rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask),
+					  PT_PAGE_TABLE_LEVEL, slot);
+		__rmap_clear_dirty(kvm, rmap_head);
 
 		/* clear the first set bit */
 		mask &= mask - 1;
@@ -1342,27 +1342,27 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
 {
 	struct kvm_memory_slot *slot;
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 	int i;
 	bool write_protected = false;
 
 	slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 
 	for (i = PT_PAGE_TABLE_LEVEL; i <= PT_MAX_HUGEPAGE_LEVEL; ++i) {
-		rmapp = __gfn_to_rmap(gfn, i, slot);
-		write_protected |= __rmap_write_protect(vcpu->kvm, rmapp, true);
+		rmap_head = __gfn_to_rmap(gfn, i, slot);
+		write_protected |= __rmap_write_protect(vcpu->kvm, rmap_head, true);
 	}
 
 	return write_protected;
 }
 
-static bool kvm_zap_rmapp(struct kvm *kvm, unsigned long *rmapp)
+static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
 	bool flush = false;
 
-	while ((sptep = rmap_get_first(*rmapp, &iter))) {
+	while ((sptep = rmap_get_first(rmap_head, &iter))) {
 		BUG_ON(!(*sptep & PT_PRESENT_MASK));
 		rmap_printk("%s: spte %p %llx.\n", __func__, sptep, *sptep);
 
@@ -1373,14 +1373,14 @@ static bool kvm_zap_rmapp(struct kvm *kvm, unsigned long *rmapp)
 	return flush;
 }
 
-static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
+static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 			   struct kvm_memory_slot *slot, gfn_t gfn, int level,
 			   unsigned long data)
 {
-	return kvm_zap_rmapp(kvm, rmapp);
+	return kvm_zap_rmapp(kvm, rmap_head);
 }
 
-static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
+static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 			     struct kvm_memory_slot *slot, gfn_t gfn, int level,
 			     unsigned long data)
 {
@@ -1395,7 +1395,7 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
 	new_pfn = pte_pfn(*ptep);
 
 restart:
-	for_each_rmap_spte(rmapp, &iter, sptep) {
+	for_each_rmap_spte(rmap_head, &iter, sptep) {
 		rmap_printk("kvm_set_pte_rmapp: spte %p %llx gfn %llx (%d)\n",
 			     sptep, *sptep, gfn, level);
 
@@ -1433,11 +1433,11 @@ struct slot_rmap_walk_iterator {
 
 	/* output fields. */
 	gfn_t gfn;
-	unsigned long *rmap;
+	struct kvm_rmap_head *rmap;
 	int level;
 
 	/* private field. */
-	unsigned long *end_rmap;
+	struct kvm_rmap_head *end_rmap;
 };
 
 static void
@@ -1496,7 +1496,7 @@ static int kvm_handle_hva_range(struct kvm *kvm,
 				unsigned long end,
 				unsigned long data,
 				int (*handler)(struct kvm *kvm,
-					       unsigned long *rmapp,
+					       struct kvm_rmap_head *rmap_head,
 					       struct kvm_memory_slot *slot,
 					       gfn_t gfn,
 					       int level,
@@ -1540,7 +1540,8 @@ static int kvm_handle_hva_range(struct kvm *kvm,
 
 static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
 			  unsigned long data,
-			  int (*handler)(struct kvm *kvm, unsigned long *rmapp,
+			  int (*handler)(struct kvm *kvm,
+					 struct kvm_rmap_head *rmap_head,
 					 struct kvm_memory_slot *slot,
 					 gfn_t gfn, int level,
 					 unsigned long data))
@@ -1563,7 +1564,7 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
 	kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
 }
 
-static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
+static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 			 struct kvm_memory_slot *slot, gfn_t gfn, int level,
 			 unsigned long data)
 {
@@ -1573,18 +1574,19 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
 
 	BUG_ON(!shadow_accessed_mask);
 
-	for_each_rmap_spte(rmapp, &iter, sptep)
+	for_each_rmap_spte(rmap_head, &iter, sptep) {
 		if (*sptep & shadow_accessed_mask) {
 			young = 1;
 			clear_bit((ffs(shadow_accessed_mask) - 1),
 				 (unsigned long *)sptep);
 		}
+	}
 
 	trace_kvm_age_page(gfn, level, slot, young);
 	return young;
 }
 
-static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
+static int kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 			      struct kvm_memory_slot *slot, gfn_t gfn,
 			      int level, unsigned long data)
 {
@@ -1600,11 +1602,12 @@ static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
 	if (!shadow_accessed_mask)
 		goto out;
 
-	for_each_rmap_spte(rmapp, &iter, sptep)
+	for_each_rmap_spte(rmap_head, &iter, sptep) {
 		if (*sptep & shadow_accessed_mask) {
 			young = 1;
 			break;
 		}
+	}
 out:
 	return young;
 }
@@ -1613,14 +1616,14 @@ out:
 
 static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 {
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 	struct kvm_mmu_page *sp;
 
 	sp = page_header(__pa(spte));
 
-	rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp);
+	rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp);
 
-	kvm_unmap_rmapp(vcpu->kvm, rmapp, NULL, gfn, sp->role.level, 0);
+	kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, 0);
 	kvm_flush_remote_tlbs(vcpu->kvm);
 }
 
@@ -1737,7 +1740,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
 	 * this feature. See the comments in kvm_zap_obsolete_pages().
 	 */
 	list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
-	sp->parent_ptes = 0;
+	sp->parent_ptes.val = 0;
 	mmu_page_add_parent_pte(vcpu, sp, parent_pte);
 	kvm_mod_used_mmu_pages(vcpu->kvm, +1);
 	return sp;
@@ -2277,7 +2280,7 @@ static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp)
 	u64 *sptep;
 	struct rmap_iterator iter;
 
-	while ((sptep = rmap_get_first(sp->parent_ptes, &iter)))
+	while ((sptep = rmap_get_first(&sp->parent_ptes, &iter)))
 		drop_parent_pte(sp, sptep);
 }
 
@@ -4492,7 +4495,7 @@ void kvm_mmu_setup(struct kvm_vcpu *vcpu)
 }
 
 /* The return value indicates if tlb flush on all vcpus is needed. */
-typedef bool (*slot_level_handler) (struct kvm *kvm, unsigned long *rmap);
+typedef bool (*slot_level_handler) (struct kvm *kvm, struct kvm_rmap_head *rmap_head);
 
 /* The caller should hold mmu-lock before calling this function. */
 static bool
@@ -4586,9 +4589,10 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 	spin_unlock(&kvm->mmu_lock);
 }
 
-static bool slot_rmap_write_protect(struct kvm *kvm, unsigned long *rmapp)
+static bool slot_rmap_write_protect(struct kvm *kvm,
+				    struct kvm_rmap_head *rmap_head)
 {
-	return __rmap_write_protect(kvm, rmapp, false);
+	return __rmap_write_protect(kvm, rmap_head, false);
 }
 
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
@@ -4624,7 +4628,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
 }
 
 static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
-		unsigned long *rmapp)
+					 struct kvm_rmap_head *rmap_head)
 {
 	u64 *sptep;
 	struct rmap_iterator iter;
@@ -4633,7 +4637,7 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 	struct kvm_mmu_page *sp;
 
 restart:
-	for_each_rmap_spte(rmapp, &iter, sptep) {
+	for_each_rmap_spte(rmap_head, &iter, sptep) {
 		sp = page_header(__pa(sptep));
 		pfn = spte_to_pfn(*sptep);
 
diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c
index 03d518e..f7b0488 100644
--- a/arch/x86/kvm/mmu_audit.c
+++ b/arch/x86/kvm/mmu_audit.c
@@ -129,7 +129,7 @@ static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level)
 static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep)
 {
 	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 	struct kvm_mmu_page *rev_sp;
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *slot;
@@ -150,8 +150,8 @@ static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep)
 		return;
 	}
 
-	rmapp = __gfn_to_rmap(gfn, rev_sp->role.level, slot);
-	if (!*rmapp) {
+	rmap_head = __gfn_to_rmap(gfn, rev_sp->role.level, slot);
+	if (!rmap_head->val) {
 		if (!__ratelimit(&ratelimit_state))
 			return;
 		audit_printk(kvm, "no rmap for writable spte %llx\n",
@@ -192,7 +192,7 @@ static void check_mappings_rmap(struct kvm *kvm, struct kvm_mmu_page *sp)
 
 static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
-	unsigned long *rmapp;
+	struct kvm_rmap_head *rmap_head;
 	u64 *sptep;
 	struct rmap_iterator iter;
 	struct kvm_memslots *slots;
@@ -203,13 +203,14 @@ static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp)
 
 	slots = kvm_memslots_for_spte_role(kvm, sp->role);
 	slot = __gfn_to_memslot(slots, sp->gfn);
-	rmapp = __gfn_to_rmap(sp->gfn, PT_PAGE_TABLE_LEVEL, slot);
+	rmap_head = __gfn_to_rmap(sp->gfn, PT_PAGE_TABLE_LEVEL, slot);
 
-	for_each_rmap_spte(rmapp, &iter, sptep)
+	for_each_rmap_spte(rmap_head, &iter, sptep) {
 		if (is_writable_pte(*sptep))
 			audit_printk(kvm, "shadow page has writable "
 				     "mappings: gfn %llx role %x\n",
 				     sp->gfn, sp->role.word);
+	}
 }
 
 static void audit_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
-- 
2.1.0