Messages in this thread |  | | Subject | Re: [PATCH] virtio_balloon: clear modern features under legacy | From | Jason Wang <> | Date | Mon, 13 Jul 2020 11:36:51 +0800 |
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On 2020/7/10 下午7:31, Michael S. Tsirkin wrote: > Page reporting features were never supported by legacy hypervisors. > Supporting them poses a problem: should we use native endian-ness (like > current code assumes)? Or little endian-ness like the virtio spec says? > Rather than try to figure out, and since results of > incorrect endian-ness are dire, let's just block this configuration. > > Cc: stable@vger.kernel.org > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > --- > drivers/virtio/virtio_balloon.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 5d4b891bf84f..b9bc03345157 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -1107,6 +1107,15 @@ static int virtballoon_restore(struct virtio_device *vdev) > > static int virtballoon_validate(struct virtio_device *vdev) > { > + /* > + * Legacy devices never specified how modern features should behave. > + * E.g. which endian-ness to use? Better not to assume anything. > + */ > + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) { > + __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT); > + __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON); > + __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING); > + } > /* > * Inform the hypervisor that our pages are poisoned or > * initialized. If we cannot do that then we should disable
Acked-by: Jason Wang <jasowang@redhat.com>
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