[PATCH] KVM: MMU: Implement simple reverse mapping

Keep in each host page frame's page->private a pointer to the shadow pte which
maps it.  If there are multiple shadow ptes mapping the page, set bit 0 of
page->private, and use the rest as a pointer to a linked list of all such
mappings.

Reverse mappings are needed because we when we cache shadow page tables, we
must protect the guest page tables from being modified by the guest, as that
would invalidate the cached ptes.

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, 1 insertions, 0 deletions

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 09bb9b4ed12d..8c48528a6e89 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -261,6 +261,7 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
         mark_page_dirty(vcpu->kvm, gfn);
         *shadow_ent |= PT_WRITABLE_MASK;
         *guest_ent |= PT_DIRTY_MASK;
+        rmap_add(vcpu->kvm, shadow_ent);
 
         return 1;
 }