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-rw-r--r--arch/x86/kvm/x86.c16
-rw-r--r--include/linux/kvm_host.h1
-rw-r--r--virt/kvm/kvm_main.c11
3 files changed, 15 insertions, 13 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a2a78547243..35f82f2c66f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3208,18 +3208,15 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_memslots *slots, *old_slots;
unsigned long *dirty_bitmap;
- r = -ENOMEM;
- dirty_bitmap = vmalloc(n);
- if (!dirty_bitmap)
- goto out;
+ dirty_bitmap = memslot->dirty_bitmap_head;
+ if (memslot->dirty_bitmap == dirty_bitmap)
+ dirty_bitmap += n / sizeof(long);
memset(dirty_bitmap, 0, n);
r = -ENOMEM;
slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
- if (!slots) {
- vfree(dirty_bitmap);
+ if (!slots)
goto out;
- }
memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
slots->memslots[log->slot].dirty_bitmap = dirty_bitmap;
slots->generation++;
@@ -3235,11 +3232,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
spin_unlock(&kvm->mmu_lock);
r = -EFAULT;
- if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n)) {
- vfree(dirty_bitmap);
+ if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n))
goto out;
- }
- vfree(dirty_bitmap);
} else {
r = -EFAULT;
if (clear_user(log->dirty_bitmap, n))
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 462b982fedf..bcf71c7730f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -150,6 +150,7 @@ struct kvm_memory_slot {
unsigned long flags;
unsigned long *rmap;
unsigned long *dirty_bitmap;
+ unsigned long *dirty_bitmap_head;
struct {
unsigned long rmap_pde;
int write_count;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0021c286214..27649fdaa00 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -449,8 +449,9 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
if (!memslot->dirty_bitmap)
return;
- vfree(memslot->dirty_bitmap);
+ vfree(memslot->dirty_bitmap_head);
memslot->dirty_bitmap = NULL;
+ memslot->dirty_bitmap_head = NULL;
}
/*
@@ -537,15 +538,21 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
return 0;
}
+/*
+ * Allocation size is twice as large as the actual dirty bitmap size.
+ * This makes it possible to do double buffering: see x86's
+ * kvm_vm_ioctl_get_dirty_log().
+ */
static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
{
- unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot);
+ unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot);
memslot->dirty_bitmap = vmalloc(dirty_bytes);
if (!memslot->dirty_bitmap)
return -ENOMEM;
memset(memslot->dirty_bitmap, 0, dirty_bytes);
+ memslot->dirty_bitmap_head = memslot->dirty_bitmap;
return 0;
}