fast fix for mmu aliasing troubles

[Izik Eidus <ieidus@redhat.com>]

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i have sent patch that remove the aliasing and i will resend it again
but untill then this patch should be applied as it fix kernel panic.

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>From 61a13744e2367572f3e27ab5c0cce6e080e94d67 Mon Sep 17 00:00:00 2001
From: Izik Eidus <ieidus@redhat.com>
Date: Fri, 3 Oct 2008 17:40:32 +0300
Subject: [PATCH] KVM: mmu: fix aliased gfns treated as unaliased ones.
 some areas of kvm x86 mmu were calcualting gfn offset inside a slot without
 unaliasing the gfn, this patch make sure that the gfn will be unaliased and add
 gfn_to_memslot_unaliased() to save the calculating of the gfn unaliasing in case
 we have it unaliased already.

Signed-off-by: Izik Eidus <ieidus@redhat.com>
---
 arch/x86/kvm/mmu.c         |   14 ++++++++++----
 include/asm-x86/kvm_host.h |    2 ++
 virt/kvm/kvm_main.c        |    9 +++++----
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 99c239c..a84b2ed 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -384,7 +384,9 @@ static void account_shadowed(struct kvm *kvm, gfn_t gfn)
 {
 	int *write_count;
 
-	write_count = slot_largepage_idx(gfn, gfn_to_memslot(kvm, gfn));
+	gfn = unalias_gfn(kvm, gfn);
+	write_count = slot_largepage_idx(gfn,
+					 gfn_to_memslot_unaliased(kvm, gfn));
 	*write_count += 1;
 }
 
@@ -392,16 +394,20 @@ static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn)
 {
 	int *write_count;
 
-	write_count = slot_largepage_idx(gfn, gfn_to_memslot(kvm, gfn));
+	gfn = unalias_gfn(kvm, gfn);
+	write_count = slot_largepage_idx(gfn,
+					 gfn_to_memslot_unaliased(kvm, gfn));
 	*write_count -= 1;
 	WARN_ON(*write_count < 0);
 }
 
 static int has_wrprotected_page(struct kvm *kvm, gfn_t gfn)
 {
-	struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
+	struct kvm_memory_slot *slot;
 	int *largepage_idx;
 
+	gfn = unalias_gfn(kvm, gfn);
+	slot = gfn_to_memslot_unaliased(kvm, gfn);
 	if (slot) {
 		largepage_idx = slot_largepage_idx(gfn, slot);
 		return *largepage_idx;
@@ -2859,8 +2865,8 @@ static void audit_write_protection(struct kvm_vcpu *vcpu)
 		if (sp->role.metaphysical)
 			continue;
 
-		slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
 		gfn = unalias_gfn(vcpu->kvm, sp->gfn);
+		slot = gfn_to_memslot_unaliased(vcpu->kvm, sp->gfn);
 		rmapp = &slot->rmap[gfn - slot->base_gfn];
 		if (*rmapp)
 			printk(KERN_ERR "%s: (%s) shadow page has writable"
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 635f50e..037f1b3 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -607,6 +607,8 @@ void kvm_disable_tdp(void);
 int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
 int complete_pio(struct kvm_vcpu *vcpu);
 
+struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn);
+
 static inline struct kvm_mmu_page *page_header(hpa_t shadow_page)
 {
 	struct page *page = pfn_to_page(shadow_page >> PAGE_SHIFT);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6cf0427..b99f196 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -674,7 +674,7 @@ int kvm_is_error_hva(unsigned long addr)
 }
 EXPORT_SYMBOL_GPL(kvm_is_error_hva);
 
-static struct kvm_memory_slot *__gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
+struct kvm_memory_slot *gfn_to_memslot_unaliased(struct kvm *kvm, gfn_t gfn)
 {
 	int i;
 
@@ -687,11 +687,12 @@ static struct kvm_memory_slot *__gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 	}
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(gfn_to_memslot_unaliased);
 
 struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 {
 	gfn = unalias_gfn(kvm, gfn);
-	return __gfn_to_memslot(kvm, gfn);
+	return gfn_to_memslot_unaliased(kvm, gfn);
 }
 
 int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
@@ -715,7 +716,7 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 	struct kvm_memory_slot *slot;
 
 	gfn = unalias_gfn(kvm, gfn);
-	slot = __gfn_to_memslot(kvm, gfn);
+	slot = gfn_to_memslot_unaliased(kvm, gfn);
 	if (!slot)
 		return bad_hva();
 	return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
@@ -966,7 +967,7 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
 	struct kvm_memory_slot *memslot;
 
 	gfn = unalias_gfn(kvm, gfn);
-	memslot = __gfn_to_memslot(kvm, gfn);
+	memslot = gfn_to_memslot_unaliased(kvm, gfn);
 	if (memslot && memslot->dirty_bitmap) {
 		unsigned long rel_gfn = gfn - memslot->base_gfn;
 
-- 
1.5.6.3