Re: [PATCH v7 31/46] vhost: virtio 1.0 endian-ness support

Michael S. Tsirkin
2014-12-01T12:37:23Z

On Mon, Dec 01, 2014 at 01:33:53PM +0100, Cornelia Huck wrote:
> On Sun, 30 Nov 2014 17:11:49 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> > drivers/vhost/vhost.c | 93 +++++++++++++++++++++++++++++++--------------------
> > 1 file changed, 56 insertions(+), 37 deletions(-)
> >
>
> > @@ -1113,18 +1120,19 @@ static int get_indirect(struct vhost_virtqueue *vq,
> > {
> > struct vring_desc desc;
> > unsigned int i = 0, count, found = 0;
> > + u32 len = vhost32_to_cpu(vq, indirect->len);
> > int ret;
> >
> > /* Sanity check */
> > - if (unlikely(indirect->len % sizeof desc)) {
> > + if (unlikely(len % sizeof desc)) {
> > vq_err(vq, "Invalid length in indirect descriptor: "
> > "len 0x%llx not multiple of 0x%zx\n",
> > - (unsigned long long)indirect->len,
> > + (unsigned long long)vhost32_to_cpu(vq, indirect->len),
>
> Can't you use len here?

Not if I want error message to be readable.

> > sizeof desc);
> > return -EINVAL;
> > }
> >
> > - ret = translate_desc(vq, indirect->addr, indirect->len, vq->indirect,
> > + ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
> > UIO_MAXIOV);
> > if (unlikely(ret < 0)) {
> > vq_err(vq, "Translation failure %d in indirect.\n", ret);
>
>
> > @@ -1404,7 +1422,7 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
> >
> > /* Make sure buffer is written before we update index. */
> > smp_wmb();
> > - if (put_user(vq->last_used_idx, &vq->used->idx)) {
> > + if (__put_user(cpu_to_vhost16(vq, vq->last_used_idx), &vq->used->idx)) {
>
> Why s/put_user/__put_user/ - I don't see how endianness conversions
> should have an influence there?

We should generally to __ variants since addresses are pre-validated.
But I agree - should be a separate patch.

>
> > vq_err(vq, "Failed to increment used idx");
> > return -EFAULT;
> > }
>
> > @@ -1449,11 +1468,11 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
> > if (unlikely(!v))
> > return true;
> >
> > - if (get_user(event, vhost_used_event(vq))) {
> > + if (__get_user(event, vhost_used_event(vq))) {
>
> Dito: why the change?

Same. Will split this out, it's unrelated to virtio 1.0.

> > vq_err(vq, "Failed to get used event idx");
> > return true;
> > }
> > - return vring_need_event(event, new, old);
> > + return vring_need_event(vhost16_to_cpu(vq, event), new, old);
> > }
> >
> > /* This actually signals the guest, using eventfd. */