Skip to contentSkip to conversation

KVM MMU: cleanup/fix mmu audit code

PATCH Applied Xiao Guangrong 3 participants 4 messages Apr 1, 2010 – Apr 5, 2010

Subsystems (3)
x86 KVM KVM x86
lore
Share & tools
lore

Xiao Guangrong

author
#0 lore raw

PATCH 1/2 KVM MMU: cleanup/fix mmu audit code

This patch does:
- 'sp' parameter in inspect_spte_fn() is not used, so remove it
- fix 'kvm' and 'slots' is not defined in count_rmaps()
- fix a bug in inspect_spte_has_rmap()

Signed-off-by Xiao Guangrong <[email protected]>
---
 arch/x86/kvm/mmu.c |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)
arch/x86/kvm/mmu.c +8 -7
index d7700bb..5de92ae 100644
@@ -3178,8 +3178,7 @@ static gva_t canonicalize(gva_t gva)
 }
 
 
-typedef void (*inspect_spte_fn) (struct kvm *kvm, struct kvm_mmu_page *sp,
-				 u64 *sptep);
+typedef void (*inspect_spte_fn) (struct kvm *kvm, u64 *sptep);
 
 static void __mmu_spte_walk(struct kvm *kvm, struct kvm_mmu_page *sp,
 			    inspect_spte_fn fn)

@@ -3195,7 +3194,7 @@ static void __mmu_spte_walk(struct kvm *kvm, struct kvm_mmu_page *sp,
 				child = page_header(ent & PT64_BASE_ADDR_MASK);
 				__mmu_spte_walk(kvm, child, fn);
 			} else
-				fn(kvm, sp, &sp->spt[i]);
+				fn(kvm, &sp->spt[i]);
 		}
 	}
 }

@@ -3286,6 +3285,8 @@ static void audit_mappings(struct kvm_vcpu *vcpu)
 
 static int count_rmaps(struct kvm_vcpu *vcpu)
 {
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_memslots *slots;
 	int nmaps = 0;
 	int i, j, k, idx;
 

@@ -3319,7 +3320,7 @@ static int count_rmaps(struct kvm_vcpu *vcpu)
 	return nmaps;
 }
 
-void inspect_spte_has_rmap(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *sptep)
+void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep)
 {
 	unsigned long *rmapp;
 	struct kvm_mmu_page *rev_sp;

@@ -3335,14 +3336,14 @@ void inspect_spte_has_rmap(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *sptep)
 			printk(KERN_ERR "%s: no memslot for gfn %ld\n",
 					 audit_msg, gfn);
 			printk(KERN_ERR "%s: index %ld of sp (gfn=%lx)\n",
-					audit_msg, sptep - rev_sp->spt,
+			       audit_msg, (long int)(sptep - rev_sp->spt),
 					rev_sp->gfn);
 			dump_stack();
 			return;
 		}
 
 		rmapp = gfn_to_rmap(kvm, rev_sp->gfns[sptep - rev_sp->spt],
-				    is_large_pte(*sptep));
+				    rev_sp->role.level);
 		if (!*rmapp) {
 			if (!printk_ratelimit())
 				return;

@@ -3377,7 +3378,7 @@ static void check_writable_mappings_rmap(struct kvm_vcpu *vcpu)
 				continue;
 			if (!(ent & PT_WRITABLE_MASK))
 				continue;
-			inspect_spte_has_rmap(vcpu->kvm, sp, &pt[i]);
+			inspect_spte_has_rmap(vcpu->kvm, &pt[i]);
 		}
 	}
 	return;
Signature · 1 line
1.6.1.2
author
#1 lore raw

PATCH 2/2 KVM MMU: record reverse mapping for spte only if it's writable

The read only spte mapping can't hurt shadow page cache, so, no need to record it.

Using bit9 to record whether the spte is re-mapped

Signed-off-by Xiao Guangrong <[email protected]>
---
 arch/x86/kvm/mmu.c |   17 +++++++++++++++--
 arch/x86/kvm/mmu.h |    1 +
 2 files changed, 16 insertions(+), 2 deletions(-)
arch/x86/kvm/mmu.c +15 -2
index 5de92ae..999f572 100644
@@ -259,7 +259,17 @@ static int is_dirty_gpte(unsigned long pte)
 
 static int is_rmap_spte(u64 pte)
 {
-	return is_shadow_present_pte(pte);
+	return pte & PT_RMAP_MASK;
+}
+
+static void spte_set_rmap(u64 *spte)
+{
+	*spte |= PT_RMAP_MASK;
+}
+
+static void spte_clear_rmap(u64 *spte)
+{
+	*spte &= ~PT_RMAP_MASK;
 }
 
 static int is_last_spte(u64 pte, int level)

@@ -543,7 +553,7 @@ static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 	unsigned long *rmapp;
 	int i, count = 0;
 
-	if (!is_rmap_spte(*spte))
+	if (!is_shadow_present_pte(*spte) || !is_writable_pte(*spte))
 		return count;
 	gfn = unalias_gfn(vcpu->kvm, gfn);
 	sp = page_header(__pa(spte));

@@ -573,6 +583,7 @@ static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 			;
 		desc->sptes[i] = spte;
 	}
+	spte_set_rmap(spte);
 	return count;
 }
 

@@ -610,6 +621,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
 
 	if (!is_rmap_spte(*spte))
 		return;
+	spte_clear_rmap(spte);
 	sp = page_header(__pa(spte));
 	pfn = spte_to_pfn(*spte);
 	if (*spte & shadow_accessed_mask)

@@ -646,6 +658,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
 		pr_err("rmap_remove: %p %llx many->many\n", spte, *spte);
 		BUG();
 	}
+
 }
 
 static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte)
arch/x86/kvm/mmu.h +1 -0
index be66759..166b9b5 100644
@@ -22,6 +22,7 @@
 #define PT_PAGE_SIZE_MASK (1ULL << 7)
 #define PT_PAT_MASK (1ULL << 7)
 #define PT_GLOBAL_MASK (1ULL << 8)
+#define PT_RMAP_MASK (1ULL << 9)
 #define PT64_NX_SHIFT 63
 #define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)
Signature · 1 line
1.6.1.2
#2 lore raw

Re: [PATCH 2/2] KVM MMU: record reverse mapping for spte only if it's writable

Quoted 4 lines · Xiao Guangrong

The read only spte mapping can't hurt shadow page cache, so, no need to record it.

We do need to keep track of read-only mappings, that's how swapping works. See commit ca335c8f08d.

Signature · 1 line
error compiling committee.c: too many arguments to function