From: Avi Kivity <avi@qumranet.com>
Date: Thu, 11 Oct 2007 10:32:30 +0000 (+0200)
Subject: KVM: Move guest pte dirty bit management to the guest pagetable walker
X-Git-Tag: v2.6.25-rc1~1138^2~218
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3c5e7ec9efe0ebd47fa812cc86f01c51905edf6;p=linux-2.6

KVM: Move guest pte dirty bit management to the guest pagetable walker

This is more consistent with the accessed bit management, and makes the dirty
bit available earlier for other purposes.

Signed-off-by: Avi Kivity <avi@qumranet.com>
---

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index d046ba8077..e6616a6c9c 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -199,6 +199,11 @@ static int is_writeble_pte(unsigned long pte)
 	return pte & PT_WRITABLE_MASK;
 }
 
+static int is_dirty_pte(unsigned long pte)
+{
+	return pte & PT_DIRTY_MASK;
+}
+
 static int is_io_pte(unsigned long pte)
 {
 	return pte & PT_SHADOW_IO_MARK;
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 8e1e4ca6ea..da36e48fd0 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -144,6 +144,10 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
 		if (walker->level == PT_PAGE_TABLE_LEVEL) {
 			walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
 				>> PAGE_SHIFT;
+			if (write_fault && !is_dirty_pte(*ptep)) {
+				mark_page_dirty(vcpu->kvm, table_gfn);
+				*ptep |= PT_DIRTY_MASK;
+			}
 			break;
 		}
 
@@ -153,6 +157,10 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
 			walker->gfn = (*ptep & PT_DIR_BASE_ADDR_MASK)
 				>> PAGE_SHIFT;
 			walker->gfn += PT_INDEX(addr, PT_PAGE_TABLE_LEVEL);
+			if (write_fault && !is_dirty_pte(*ptep)) {
+				mark_page_dirty(vcpu->kvm, table_gfn);
+				*ptep |= PT_DIRTY_MASK;
+			}
 			break;
 		}
 
@@ -194,12 +202,6 @@ err:
 	return 0;
 }
 
-static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
-					struct guest_walker *walker)
-{
-	mark_page_dirty(kvm, walker->table_gfn[walker->level - 1]);
-}
-
 static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
 				  u64 *shadow_pte,
 				  gpa_t gaddr,
@@ -221,23 +223,6 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
 		 __FUNCTION__, *shadow_pte, (u64)gpte, access_bits,
 		 write_fault, user_fault, gfn);
 
-	if (write_fault && !dirty) {
-		pt_element_t *guest_ent, *tmp = NULL;
-
-		if (walker->ptep)
-			guest_ent = walker->ptep;
-		else {
-			tmp = kmap_atomic(walker->page, KM_USER0);
-			guest_ent = &tmp[walker->index];
-		}
-
-		*guest_ent |= PT_DIRTY_MASK;
-		if (!walker->ptep)
-			kunmap_atomic(tmp, KM_USER0);
-		dirty = 1;
-		FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
-	}
-
 	/*
 	 * We don't set the accessed bit, since we sometimes want to see
 	 * whether the guest actually used the pte (in order to detect