[PATCH 07/13] KVM: MMU: store more bits in rmap

[Xiao Guangrong]

In current code, only one bit (bit 0) is used in rmap, this patch export
more bits from rmap, during pte add/remove, it only touches bit 0 and other
bits are keeped

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
---
 arch/x86/kvm/mmu.c |  143 +++++++++++++++++++++++++++++++++-------------------
 1 files changed, 91 insertions(+), 52 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bb4d292..84b9775 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -796,6 +796,17 @@ static int mapping_level(struct kvm_vcpu *vcpu, gfn_t large_gfn)
 	return level - 1;
 }

+#define PTE_LIST_DESC		(0x1ull)
+#define PTE_LIST_FLAG_MASK	(0x3ull)
+
+static void
+pte_list_decode(const unsigned long *pte_list, unsigned long *map,
+		unsigned long *flags)
+{
+	*map = *pte_list & (~PTE_LIST_FLAG_MASK);
+	*flags = *pte_list & PTE_LIST_FLAG_MASK;
+}
+
 /*
  * Pte mapping structures:
  *
@@ -812,50 +823,67 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
 			unsigned long *pte_list)
 {
 	struct pte_list_desc *desc;
+	unsigned long map, flags;
 	int i, count = 0;

-	if (!*pte_list) {
+	pte_list_decode(pte_list, &map, &flags);
+
+	if (!map) {
 		rmap_printk("pte_list_add: %p %llx 0->1\n", spte, *spte);
-		*pte_list = (unsigned long)spte;
-	} else if (!(*pte_list & 1)) {
+		WARN_ON(flags & PTE_LIST_DESC);
+		*pte_list = (unsigned long)spte | flags ;
+
+		return 0;
+	}
+
+	if (!(flags & PTE_LIST_DESC)) {
 		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 *)map;
 		desc->sptes[1] = spte;
-		*pte_list = (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);
-		while (desc->sptes[PTE_LIST_EXT-1] && desc->more) {
-			desc = desc->more;
-			count += PTE_LIST_EXT;
-		}
-		if (desc->sptes[PTE_LIST_EXT-1]) {
-			desc->more = mmu_alloc_pte_list_desc(vcpu);
-			desc = desc->more;
-		}
-		for (i = 0; desc->sptes[i]; ++i)
-			++count;
-		desc->sptes[i] = spte;
+		*pte_list = (unsigned long)desc | flags | PTE_LIST_DESC;
+
+		return 1;
+	}
+
+	rmap_printk("pte_list_add: %p %llx many->many\n", spte, *spte);
+	desc = (struct pte_list_desc *)map;
+	while (desc->sptes[PTE_LIST_EXT - 1] && desc->more) {
+		desc = desc->more;
+		count += PTE_LIST_EXT;
+	}
+
+	if (desc->sptes[PTE_LIST_EXT - 1]) {
+		desc->more = mmu_alloc_pte_list_desc(vcpu);
+		desc = desc->more;
 	}
+
+	for (i = 0; desc->sptes[i]; ++i)
+		++count;
+	desc->sptes[i] = spte;
+
 	return count;
 }

 static u64 *pte_list_next(unsigned long *pte_list, u64 *spte)
 {
 	struct pte_list_desc *desc;
+	unsigned long map, flags;
 	u64 *prev_spte;
 	int i;

-	if (!*pte_list)
+	pte_list_decode(pte_list, &map, &flags);
+
+	if (!map)
 		return NULL;
-	else if (!(*pte_list & 1)) {
+
+	if (!(flags & PTE_LIST_DESC)) {
 		if (!spte)
-			return (u64 *)*pte_list;
+			return (u64 *)map;
 		return NULL;
 	}
-	desc = (struct pte_list_desc *)(*pte_list & ~1ul);
+
+	desc = (struct pte_list_desc *)map;
 	prev_spte = NULL;
 	while (desc) {
 		for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i) {
@@ -870,7 +898,8 @@ static u64 *pte_list_next(unsigned long *pte_list, 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)
+			   int i, struct pte_list_desc *prev_desc,
+			   unsigned long flags)
 {
 	int j;

@@ -881,12 +910,13 @@ 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];
+		*pte_list = (unsigned long)desc->sptes[0] |
+					(flags & (~PTE_LIST_DESC)) ;
 	else
 		if (prev_desc)
 			prev_desc->more = desc->more;
 		else
-			*pte_list = (unsigned long)desc->more | 1;
+			*pte_list = (unsigned long)desc->more | flags;
 	mmu_free_pte_list_desc(desc);
 }

@@ -894,51 +924,60 @@ static void pte_list_remove(u64 *spte, unsigned long *pte_list)
 {
 	struct pte_list_desc *desc;
 	struct pte_list_desc *prev_desc;
+	unsigned long map, flags;
 	int i;

-	if (!*pte_list) {
+	pte_list_decode(pte_list, &map, &flags);
+
+	if (!map) {
 		printk(KERN_ERR "pte_list_remove: %p 0->BUG\n", spte);
 		BUG();
-	} else if (!(*pte_list & 1)) {
+		return;
+	}
+
+	if (!(flags & PTE_LIST_DESC)) {
 		rmap_printk("pte_list_remove:  %p 1->0\n", spte);
-		if ((u64 *)*pte_list != spte) {
+		if ((u64 *)map != spte) {
 			printk(KERN_ERR "pte_list_remove:  %p 1->BUG\n", spte);
 			BUG();
 		}
-		*pte_list = 0;
-	} else {
-		rmap_printk("pte_list_remove:  %p many->many\n", spte);
-		desc = (struct pte_list_desc *)(*pte_list & ~1ul);
-		prev_desc = NULL;
-		while (desc) {
-			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);
-					return;
-				}
-			prev_desc = desc;
-			desc = desc->more;
-		}
-		pr_err("pte_list_remove: %p many->many\n", spte);
-		BUG();
+		*pte_list = flags;
+		return;
+	}
+
+	rmap_printk("pte_list_remove:  %p many->many\n", spte);
+	desc = (struct pte_list_desc *)map;
+	prev_desc = NULL;
+	while (desc) {
+		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, flags);
+				return;
+			}
+		prev_desc = desc;
+		desc = desc->more;
 	}
+	pr_err("pte_list_remove: %p many->many\n", spte);
+	BUG();
 }

 typedef void (*pte_list_walk_fn) (u64 *spte);
 static void pte_list_walk(unsigned long *pte_list, pte_list_walk_fn fn)
 {
 	struct pte_list_desc *desc;
+	unsigned long map, flags;
 	int i;

-	if (!*pte_list)
+	pte_list_decode(pte_list, &map, &flags);
+
+	if (!map)
 		return;

-	if (!(*pte_list & 1))
-		return fn((u64 *)*pte_list);
+	if (!(flags & PTE_LIST_DESC))
+		return fn((u64 *)map);

-	desc = (struct pte_list_desc *)(*pte_list & ~1ul);
+	desc = (struct pte_list_desc *)map;
 	while (desc) {
 		for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
 			fn(desc->sptes[i]);
-- 
1.7.7.6

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