On Thu, Jun 5, 2025 at 4:55 PM Eugenio Perez Martin <epere...@redhat.com> wrote: > > On Thu, Jun 5, 2025 at 1:50 PM David Marchand <david.march...@redhat.com> > wrote: > > > > On Thu, Jun 5, 2025 at 1:36 PM Eugenio Pérez <epere...@redhat.com> wrote: > > > > > > QEMU's shadow virtqueue and VDUSE exposes these areas as read-only. If > > > we don't change it, vhost_iova_to_vva do not consider them as valid and > > > returns that they're not found. > > > > > > Eugenio Pérez (2): > > > vhost: search the split vq desc and avail in RO areas > > > vhost: search the packed vq driver area in RO areas > > > > > > lib/vhost/vhost.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > At a quick glance, no need for two patches. > > > > Sure I can respin with both squashed. > > > Sorry, the implication of this issue is not clear to me. > > What is the impact from a user pov? > > > > QEMU maps the CVQ descriptors and avail vring through as read only > maps in the case of vDPA. But DPDK is looking for them with RW > permissions, so the vhost_iova_to_vva function never selects the right > one as valid. > > Looking for them with RO still picks the map if it is mapped as RW, > but the reverse is not true.
Ok, thanks. Well, it's better, but still hard to tell how this impacts existing usecases :-). After discussing with Maxime, I understand that the shadow CVQ just can't work => blocking multi queue support with vduse for example. This is the type of high level impact I was looking for. > Let me know if you want me to respin the series with this comment too! Ideally yes, but maybe Maxime can do it when applying. -- David Marchand
