KVM: MMU: Selectively set PageDirty when releasing guest memory

Improve dirty bit setting for pages that kvm release, until now every page
that we released we marked dirty, from now only pages that have potential
to get dirty we mark dirty.

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

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 4e1bd9488470..729573b844e5 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -543,13 +543,19 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
-void kvm_release_page(struct page *page)
+void kvm_release_page_clean(struct page *page)
+{
+        put_page(page);
+}
+EXPORT_SYMBOL_GPL(kvm_release_page_clean);
+
+void kvm_release_page_dirty(struct page *page)
 {
         if (!PageReserved(page))
                 SetPageDirty(page);
         put_page(page);
 }
-EXPORT_SYMBOL_GPL(kvm_release_page);
+EXPORT_SYMBOL_GPL(kvm_release_page_dirty);
 
 static int next_segment(unsigned long len, int offset)
 {
@@ -1055,7 +1061,7 @@ static struct page *kvm_vm_nopage(struct vm_area_struct *vma,
         /* current->mm->mmap_sem is already held so call lockless version */
         page = __gfn_to_page(kvm, pgoff);
         if (is_error_page(page)) {
-                kvm_release_page(page);
+                kvm_release_page_clean(page);
                 return NOPAGE_SIGBUS;
         }
         if (type != NULL)