linux-kernel - [PATCH 7/10] KVM MMU: allow more page become unsync at gfn mapping time

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <4BCFE901.9080708@cn.fujitsu.com>
Date:	Thu, 22 Apr 2010 14:13:21 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	KVM list <kvm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 7/10] KVM MMU: allow more page become unsync at gfn mapping
 time

In current code, shadow page can become asynchronous only if one
shadow page for a gfn, this rule is too strict, in fact, we can
let all last mapping page(i.e, it's the pte page) become unsync,
and sync them at invlpg or flush tlb time.

This patch allow more page become asynchronous at gfn mapping time 

Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
 arch/x86/kvm/mmu.c |   81 +++++++++++++++++++++++----------------------------
 1 files changed, 37 insertions(+), 44 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8607a64..13378e7 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1166,26 +1166,6 @@ static int mmu_unsync_walk(struct kvm_mmu_page *sp,
 	return __mmu_unsync_walk(sp, pvec);
 }
 
-static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn)
-{
-	unsigned index;
-	struct hlist_head *bucket;
-	struct kvm_mmu_page *sp;
-	struct hlist_node *node;
-
-	pgprintk("%s: looking for gfn %lx\n", __func__, gfn);
-	index = kvm_page_table_hashfn(gfn);
-	bucket = &kvm->arch.mmu_page_hash[index];
-	hlist_for_each_entry(sp, node, bucket, hash_link)
-		if (sp->gfn == gfn && !sp->role.direct
-		    && !sp->role.invalid) {
-			pgprintk("%s: found role %x\n",
-				 __func__, sp->role.word);
-			return sp;
-		}
-	return NULL;
-}
-
 static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
 	WARN_ON(!sp->unsync);
@@ -1734,47 +1714,60 @@ u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_get_guest_memory_type);
 
-static int kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
+static void __kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
+{
+	trace_kvm_mmu_unsync_page(sp);
+	++vcpu->kvm->stat.mmu_unsync;
+	sp->unsync = 1;
+
+	kvm_mmu_mark_parents_unsync(sp);
+	mmu_convert_notrap(sp);
+}
+
+static void kvm_unsync_pages(struct kvm_vcpu *vcpu,  gfn_t gfn)
 {
-	unsigned index;
 	struct hlist_head *bucket;
 	struct kvm_mmu_page *s;
 	struct hlist_node *node, *n;
+	unsigned index;
 
-	index = kvm_page_table_hashfn(sp->gfn);
+	index = kvm_page_table_hashfn(gfn);
 	bucket = &vcpu->kvm->arch.mmu_page_hash[index];
-	/* don't unsync if pagetable is shadowed with multiple roles */
+
 	hlist_for_each_entry_safe(s, node, n, bucket, hash_link) {
-		if (s->gfn != sp->gfn || s->role.direct)
+		if (s->gfn != gfn || s->role.direct || s->unsync)
 			continue;
-		if (s->role.word != sp->role.word)
-			return 1;
+		WARN_ON(s->role.level != PT_PAGE_TABLE_LEVEL);
+		__kvm_unsync_page(vcpu, s);
 	}
-	trace_kvm_mmu_unsync_page(sp);
-	++vcpu->kvm->stat.mmu_unsync;
-	sp->unsync = 1;
-
-	kvm_mmu_mark_parents_unsync(sp);
-
-	mmu_convert_notrap(sp);
-	return 0;
 }
 
 static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
 				  bool can_unsync)
 {
-	struct kvm_mmu_page *shadow;
+	unsigned index;
+	struct hlist_head *bucket;
+	struct kvm_mmu_page *s;
+	struct hlist_node *node, *n;
+	bool need_unsync = false;
+
+	index = kvm_page_table_hashfn(gfn);
+	bucket = &vcpu->kvm->arch.mmu_page_hash[index];
+	hlist_for_each_entry_safe(s, node, n, bucket, hash_link) {
+		if (s->gfn != gfn || s->role.direct)
+			continue;
 
-	shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn);
-	if (shadow) {
-		if (shadow->role.level != PT_PAGE_TABLE_LEVEL)
+		if (s->role.level != PT_PAGE_TABLE_LEVEL)
 			return 1;
-		if (shadow->unsync)
-			return 0;
-		if (can_unsync && oos_shadow)
-			return kvm_unsync_page(vcpu, shadow);
-		return 1;
+
+		if (!need_unsync && !s->unsync) {
+			if (!can_unsync || !oos_shadow)
+				return 1;
+			need_unsync = true;
+		}
 	}
+	if (need_unsync)
+		kvm_unsync_pages(vcpu, gfn);
 	return 0;
 }
 
-- 
1.6.1.2


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/