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| author | Alex Williamson <alex.williamson@redhat.com> | 2012-12-10 10:32:45 -0700 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-12-13 23:21:50 -0200 |
| commit | f0736cf0550b349a5d5a374d65ca0488cc2eee40 (patch) | |
| tree | d72fbc1acd03c5047961bcfb5d4063137a392384 /virt/kvm | |
| parent | f3200d00ea42e485772ff92d6d649aa8eeb640c0 (diff) | |
| download | lwn-f0736cf0550b349a5d5a374d65ca0488cc2eee40.tar.gz lwn-f0736cf0550b349a5d5a374d65ca0488cc2eee40.zip | |
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/kvm')
| -rw-r--r-- | virt/kvm/kvm_main.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1cd693a76a51..3caf8162eb6b 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; |