On Mon, Jul 13, 2020 at 01:35:39PM -0700, Alexander Duyck wrote: > From: Alexander Duyck <[email protected]> > > The poison_val field in the virtio_balloon_config is treated as a > little-endian field by the host. Since we are currently only having to deal > with a single byte poison value this isn't a problem, however if the value > should ever expand it would cause byte ordering issues. Document that in > the code so that we know that if the value should ever expand we need to > byte swap the value on big-endian architectures. > > Signed-off-by: Alexander Duyck <[email protected]>
Queued, thanks! > --- > drivers/virtio/virtio_balloon.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 1f157d2f4952..d0fd8f8dc6ed 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -974,6 +974,11 @@ static int virtballoon_probe(struct virtio_device *vdev) > /* > * Let the hypervisor know that we are expecting a > * specific value to be written back in balloon pages. > + * > + * If the PAGE_POISON value was larger than a byte we would > + * need to byte swap poison_val here to guarantee it is > + * little-endian. However for now it is a single byte so we > + * can pass it as-is. > */ > if (!want_init_on_free()) > memset(&poison_val, PAGE_POISON, sizeof(poison_val));
