KVM: introduce wrapper functions for creating/destroying dirty bitmaps

This makes it easy to change the way of allocating/freeing dirty bitmaps.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 23 insertions, 7 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 880370caf9ed..0021c2862140 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -444,6 +444,15 @@ out_err_nodisable:
         return ERR_PTR(r);
 }
 
+static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
+{
+        if (!memslot->dirty_bitmap)
+                return;
+
+        vfree(memslot->dirty_bitmap);
+        memslot->dirty_bitmap = NULL;
+}
+
 /*
  * Free any memory in @free but not in @dont.
  */
@@ -456,7 +465,7 @@ static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
                 vfree(free->rmap);
 
         if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
-                vfree(free->dirty_bitmap);
+                kvm_destroy_dirty_bitmap(free);
 
 
         for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i) {
@@ -467,7 +476,6 @@ static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
         }
 
         free->npages = 0;
-        free->dirty_bitmap = NULL;
         free->rmap = NULL;
 }
 
@@ -529,6 +537,18 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
         return 0;
 }
 
+static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
+{
+        unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot);
+
+        memslot->dirty_bitmap = vmalloc(dirty_bytes);
+        if (!memslot->dirty_bitmap)
+                return -ENOMEM;
+
+        memset(memslot->dirty_bitmap, 0, dirty_bytes);
+        return 0;
+}
+
 /*
  * Allocate some memory and give it an address in the guest physical address
  * space.
@@ -663,12 +683,8 @@ skip_lpage:
 
         /* Allocate page dirty bitmap if needed */
         if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
-                unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(&new);
-
-                new.dirty_bitmap = vmalloc(dirty_bytes);
-                if (!new.dirty_bitmap)
+                if (kvm_create_dirty_bitmap(&new) < 0)
                         goto out_free;
-                memset(new.dirty_bitmap, 0, dirty_bytes);
                 /* destroy any largepage mappings for dirty tracking */
                 if (old.npages)
                         flush_shadow = 1;