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

(cherry picked from 6f89724829cfd4ad6771a92fd4b8d59c90c7220c)

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index de7df353371c0fcc698bfa1b9e2d6e88b3c42528..f685833427ba67365055e5654c3411cf8a05cbb6 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -821,7 +821,10 @@ 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);