KVM: Really remove a slot when a user ask us so

Right now, KVM does not remove a slot when we do a
register ioctl for size 0 (would be the expected behaviour).

Instead, we only mark it as empty, but keep all bitmaps
and allocated data structures present. It completely
nullifies our chances of reusing that same slot again
for mapping a different piece of memory.

In this patch, we destroy rmaps, and vfree() the
pointers that used to hold the dirty bitmap, rmap
and lpage_info structures.

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e41d39d6b0efd8e33bfd035b9083fe23f7642973..fd9cc79092cb293584923b0b2589f1ba5d60f473 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1020,7 +1020,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
                goto out_free;
        }
 
-       kvm_free_physmem_slot(&old, &new);
+       kvm_free_physmem_slot(&old, npages ? &new : NULL);
+       /* Slot deletion case: we have to update the current slot */
+       if (!npages)
+               *memslot = old;
 #ifdef CONFIG_DMAR
        /* map the pages in iommu page table */
        r = kvm_iommu_map_pages(kvm, base_gfn, npages);