| Message ID | 20241103212854.1436046-3-benjamin@sipsolutions.net |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Enable virtio-fs and virtio-snd in UML | expand |
On Sun, 2024-11-03 at 22:28 +0100, Benjamin Berg wrote: > From: Benjamin Berg <benjamin.berg@intel.com> > > It appears that the different vhost device implementations use different > sizes of the virtual queues. Add device specific limitations (for now, > only for sound), to ensure that we do not get disconnected unexpectedly. I'm not convinced this makes sense. If anything, it's a workaround for some specific userspace, but ... do we care enough and not let them fix it? The protocol [1] basically says we decide on the size (see VHOST_USER_SET_VRING_NUM) and the device doesn't even need to allocate the memory, that's on us? [1] https://qemu-project.gitlab.io/qemu/interop/vhost-user.html So maybe let's see what they were thinking? I'm not sure it's important enough right now to have this working to apply such a workaround without some further discussion? On PCI it seems that you can and should query the desired queue size (see e.g. vp_modern_get_queue_size), but with vhost-user that doesn't seem to be supported at all, so there isn't really a good thing we could do in that sense. johannes
diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c index c602892f329f..2e4b4eadd553 100644 --- a/arch/um/drivers/virtio_uml.c +++ b/arch/um/drivers/virtio_uml.c @@ -25,6 +25,7 @@ #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/virtio.h> +#include <linux/virtio_ids.h> #include <linux/virtio_config.h> #include <linux/virtio_ring.h> #include <linux/time-internal.h> @@ -935,9 +936,19 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev, struct platform_device *pdev = vu_dev->pdev; struct virtio_uml_vq_info *info; struct virtqueue *vq; - int num = MAX_SUPPORTED_QUEUE_SIZE; + int num; int rc; + /* Seems like we need to hard-code the queue size */ + switch (vu_dev->vdev.id.device) { + case VIRTIO_ID_SOUND: + num = 64; + break; + default: + num = MAX_SUPPORTED_QUEUE_SIZE; + break; + } + info = kzalloc(sizeof(*info), GFP_KERNEL); if (!info) { rc = -ENOMEM;