KVM: MMU: Fix aliased gfns treated as unaliased

Some areas of kvm x86 mmu are using gfn offset inside a slot without
unaliasing the gfn first.  This patch makes 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>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

3 files changed, 17 insertions, 8 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 09e6c56572cb..99e3cc149d21 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -617,6 +617,8 @@ 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/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 8687758b5295..8904e8ada978 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -386,7 +386,9 @@ 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;
 }
 
@@ -394,16 +396,20 @@ 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;
@@ -2973,8 +2979,8 @@ 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/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1838052f3c9e..a65baa9039d5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -923,7 +923,7 @@ 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;
 
@@ -936,11 +936,12 @@ 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)
@@ -964,7 +965,7 @@ 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);
@@ -1215,7 +1216,7 @@ 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;