On Thu, Dec 06, 2012 at 03:20:37PM -0700, Alex Williamson wrote:
> The API documents that only flags and guest physical memory space can
> be modified on an existing slot, but we don't enforce that the
> userspace address cannot be modified. Instead we just ignore it.
> This means that a user may think they've successfully moved both the
> guest and user addresses, when in fact only the guest address changed.
> Check and error instead.
>
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
> virt/kvm/kvm_main.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e426704..93213e1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -779,13 +779,19 @@ int __kvm_set_memory_region(struct kvm *kvm,
>
> r = -ENOMEM;
>
> - /* Allocate if a slot is being created */
> + /*
> + * Allocate if a slot is being created. If modifying a slot,
> + * the userspace_addr cannot change.
> + */
> if (!old.npages) {
> new.user_alloc = user_alloc;
> new.userspace_addr = mem->userspace_addr;
>
> if (kvm_arch_create_memslot(&new, npages))
> goto out_free;
> + } else if (mem->userspace_addr != old.userspace_addr) {
> + r = -EINVAL;
> + goto out_free;
> }
>
> /* Allocate page dirty bitmap if needed */
>
hmmm...does this mean that on a 'destroy', where npages is 0, the user
has to set up userspace_addr correctly? If so, that would appear to be
an unwanted change in semantics here.
Thanks,
-Jason
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