On Fri, Mar 28, 2025 at 6:34 AM Sahil Siddiq <icegambi...@gmail.com> wrote:
>
> Hi,
>
> On 3/26/25 5:36 PM, Eugenio Perez Martin wrote:
> > On Mon, Mar 24, 2025 at 3:00 PM Sahil Siddiq <icegambi...@gmail.com> wrote:
> >>
> >> Validate transport device features required for utilizing packed SVQ
> >> that both guests can use with the SVQ and SVQs can use with vdpa.
> >>
> >> Signed-off-by: Sahil Siddiq <sahil...@proton.me>
> >> ---
> >> Changes from v4 -> v5:
> >> - Split from commit #2 in v4.
> >>
> >> hw/virtio/vhost-shadow-virtqueue.c | 3 +++
> >> 1 file changed, 3 insertions(+)
> >>
> >> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> >> b/hw/virtio/vhost-shadow-virtqueue.c
> >> index 8430b3c94a..035ab1e66f 100644
> >> --- a/hw/virtio/vhost-shadow-virtqueue.c
> >> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> >> @@ -33,6 +33,9 @@ bool vhost_svq_valid_features(uint64_t features, Error
> >> **errp)
> >> ++b) {
> >> switch (b) {
> >> case VIRTIO_F_ANY_LAYOUT:
> >> + case VIRTIO_F_RING_PACKED:
> >> + case VIRTIO_F_RING_RESET:
> >> + case VIRTIO_RING_F_INDIRECT_DESC:
> >
> > This should only enable _F_RING_PACKED, there is no code supporting
> > either reset or indirect descriptors.
> >
>
> Without _F_RING_RESET and _RING_F_INDIRECT_DESC, I get the following error:
>
> qemu-system-x86_64: -netdev
> type=vhost-vdpa,vhostdev=/dev/vhost-vdpa-0,x-svq=true,id=vhost-vdpa0: SVQ
> Invalid device feature flags, offer: 0x1071011ffa7, ok: 0x70011ffa7
>
> Evaluating 0x1071011ffa7 & ~0x70011ffa7 gives me 0x10010000000 as the
> set of invalid features. This corresponds to _F_RING_RESET (1 << 40)
> and _RING_F_INDIRECT_DESC (1 << 28) [1].
>
> I get this error when x-svq=true irrespective of whether split vqs or packed
> vqs are used.
>
> Is there a way to turn them off in the QEMU command?
>
In the case of nested virtualization you should be able to disable it by:
-device virtio-net-pci,indirect_desc=off,queue_reset=off,...
In L0 QEMU cmdline.
> Thanks,
> Sahil
>
> [1]
> https://gitlab.com/qemu-project/qemu/-/blob/master/include/standard-headers/linux/virtio_config.h
>
