[PATCH] KVM: MMU: Teach the page table walker to track guest page table gfns

Saving the table gfns removes the need to walk the guest and host page tables
in lockstep.

Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 8c48528a6e89..3a35c8067dec 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -52,6 +52,7 @@
  */
 struct guest_walker {
         int level;
+        gfn_t table_gfn;
         pt_element_t *table;
         pt_element_t inherited_ar;
 };
@@ -63,8 +64,8 @@ static void FNAME(init_walker)(struct guest_walker *walker,
         struct kvm_memory_slot *slot;
 
         walker->level = vcpu->mmu.root_level;
-        slot = gfn_to_memslot(vcpu->kvm,
-                              (vcpu->cr3 & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
+        walker->table_gfn = (vcpu->cr3 & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
+        slot = gfn_to_memslot(vcpu->kvm, walker->table_gfn);
         hpa = safe_gpa_to_hpa(vcpu, vcpu->cr3 & PT64_BASE_ADDR_MASK);
         walker->table = kmap_atomic(pfn_to_page(hpa >> PAGE_SHIFT), KM_USER0);
 
@@ -133,6 +134,8 @@ static pt_element_t *FNAME(fetch_guest)(struct kvm_vcpu *vcpu,
                         return &walker->table[index];
                 if (walker->level != 3 || is_long_mode(vcpu))
                         walker->inherited_ar &= walker->table[index];
+                walker->table_gfn = (walker->table[index] & PT_BASE_ADDR_MASK)
+                        >> PAGE_SHIFT;
                 paddr = safe_gpa_to_hpa(vcpu, walker->table[index] & PT_BASE_ADDR_MASK);
                 kunmap_atomic(walker->table, KM_USER0);
                 walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),