On Tue, Aug 25, 2020 at 03:41:10PM +0200, Guennadi Liakhovetski wrote:
Hi Michael,
...back from holidays and still unsure what your preferred solution for the message layout would be:
On Wed, Aug 12, 2020 at 02:32:43PM +0200, Guennadi Liakhovetski wrote:
Hi Michael,
Thanks for a review.
On Mon, Aug 10, 2020 at 09:44:15AM -0400, Michael S. Tsirkin wrote:
On Tue, Aug 04, 2020 at 05:19:17PM +0200, Guennadi Liakhovetski wrote:
[snip]
+static int vhost_rpmsg_get_single(struct vhost_virtqueue *vq) +{
- struct vhost_rpmsg *vr = container_of(vq->dev, struct vhost_rpmsg, dev);
- unsigned int out, in;
- int head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov), &out, &in,
NULL, NULL);- if (head < 0) {
vq_err(vq, "%s(): error %d getting buffer\n",__func__, head);return head;- }
- /* Nothing new? */
- if (head == vq->num)
return head;- if (vq == &vr->vq[VIRTIO_RPMSG_RESPONSE] && (out || in != 1)) {
This in != 1 looks like a dependency on a specific message layout. virtio spec says to avoid these. Using iov iters it's not too hard to do ...
This is an RPMsg VirtIO implementation, and it has to match the virtio_rpmsg_bus.c driver, and that one has specific VirtIO queue and message usage patterns.
That could be fine for legacy virtio, but now you are claiming support for virtio 1, so need to fix these assumptions in the device.
I can just deop these checks without changing anything else, that still would work. I could also make this work with "any" layout - either ignoring any left-over buffers or maybe even getting them one by one. But I wouldn't even be able to test those modes without modifying / breaking the current virtio-rpmsg driver. What's the preferred solution?
Could you elaborate a bit please?
Thanks Guennadi
I'd prefer it that we make it work with any layout. For testing, there was a hack for virtio ring which split up descriptors at a random boundary. I'll try to locate it and post, sounds like something we might want upstream for debugging.