Linux commit v5.14-rc1~30^2~8 enabled the vp_vdpa driver to set the vq state to the device's initial state. This works differently for split and packed vqs.
With shadow virtqueues enabled, vhost-vdpa sets the vring base using the VHOST_SET_VRING_BASE ioctl. The payload (vhost_vring_state) differs for split and packed vqs. The implementation in QEMU currently uses the payload required for split vqs (i.e., the num field of vhost_vring_state is set to 0). The kernel throws EOPNOTSUPP when this payload is used with packed vqs. This patch sets the num field in the payload appropriately so vhost-vdpa (with the vp_vdpa driver) can use packed svqs. Link: https://lists.nongnu.org/archive/html/qemu-devel/2024-10/msg05106.html Link: https://lore.kernel.org/r/20210602021536.39525-4-jasow...@redhat.com Signed-off-by: Sahil Siddiq <sahil...@proton.me> --- QEMU currently does not support packed vhost shadow virtqueues. I am working on adding support for packed svqs [1]. The test environment that I am using [2] requires vhost-vdpa to use the relevant payload when setting vring base. [1] https://wiki.qemu.org/Internships/ProjectIdeas/PackedShadowVirtqueue [2] https://www.redhat.com/en/blog/hands-vdpa-what-do-you-do-when-you-aint-got-hardware-part-2 hw/virtio/vhost-vdpa.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c index 3cdaa12ed5..5f81945109 100644 --- a/hw/virtio/vhost-vdpa.c +++ b/hw/virtio/vhost-vdpa.c @@ -1230,6 +1230,10 @@ static bool vhost_vdpa_svq_setup(struct vhost_dev *dev, }; int r; + if (virtio_vdev_has_feature(dev->vdev, VIRTIO_F_RING_PACKED)) { + s.num = 0x80008000; + } + r = vhost_vdpa_set_dev_vring_base(dev, &s); if (unlikely(r)) { error_setg_errno(errp, -r, "Cannot set vring base"); -- 2.47.0
