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authorAlex Williamson <alex.williamson@redhat.com>2012-12-10 10:32:45 -0700
committerMarcelo Tosatti <mtosatti@redhat.com>2012-12-13 23:21:50 -0200
commitf0736cf0550b349a5d5a374d65ca0488cc2eee40 (patch)
treed72fbc1acd03c5047961bcfb5d4063137a392384 /virt
parentf3200d00ea42e485772ff92d6d649aa8eeb640c0 (diff)
downloadlinux-f0736cf0550b349a5d5a374d65ca0488cc2eee40.tar.gz
KVM: Restrict non-existing slot state transitions
The API documentation states: When changing an existing slot, it may be moved in the guest physical memory space, or its flags may be modified. An "existing slot" requires a non-zero npages (memory_size). The only transition we should therefore allow for a non-existing slot should be to create the slot, which includes setting a non-zero memory_size. We currently allow calls to modify non-existing slots, which is pointless, confusing, and possibly wrong. With this we know that the invalidation path of __kvm_set_memory_region is always for a delete or move and never for adding a zero size slot. Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1cd693a76a5..3caf8162eb6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -758,10 +758,15 @@ int __kvm_set_memory_region(struct kvm *kvm,
new.npages = npages;
new.flags = mem->flags;
- /* Disallow changing a memory slot's size. */
+ /*
+ * Disallow changing a memory slot's size or changing anything about
+ * zero sized slots that doesn't involve making them non-zero.
+ */
r = -EINVAL;
if (npages && old.npages && npages != old.npages)
goto out_free;
+ if (!npages && !old.npages)
+ goto out_free;
/* Check for overlaps */
r = -EEXIST;
@@ -780,7 +785,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
r = -ENOMEM;
/* Allocate if a slot is being created */
- if (npages && !old.npages) {
+ if (!old.npages) {
new.user_alloc = user_alloc;
new.userspace_addr = mem->userspace_addr;