On Thu, Sep 4, 2025 at 11:08 AM Jason Wang <jasow...@redhat.com> wrote:
>
> On Wed, Sep 3, 2025 at 6:31 PM Eugenio Perez Martin <epere...@redhat.com>
> wrote:
> >
> > On Wed, Sep 3, 2025 at 9:40 AM Jason Wang <jasow...@redhat.com> wrote:
> > >
> > > On Wed, Sep 3, 2025 at 2:29 PM Eugenio Perez Martin <epere...@redhat.com>
> > > wrote:
> > > >
> > > > On Wed, Sep 3, 2025 at 5:58 AM Jason Wang <jasow...@redhat.com> wrote:
> > > > >
> > > > > On Mon, Sep 1, 2025 at 4:40 PM Eugenio Perez Martin
> > > > > <epere...@redhat.com> wrote:
> > > > > >
> > > > > > On Mon, Sep 1, 2025 at 3:59 AM Jason Wang <jasow...@redhat.com>
> > > > > > wrote:
> > > > > > >
> > > > > > > On Tue, Aug 26, 2025 at 7:27 PM Eugenio Pérez
> > > > > > > <epere...@redhat.com> wrote:
> > > > > > > >
> > > > > > > > This allows sepparate the different virtqueues in groups that
> > > > > > > > shares the
> > > > > > > > same address space. Asking the VDUSE device for the groups of
> > > > > > > > the vq at
> > > > > > > > the beginning as they're needed for the DMA API.
> > > > > > > >
> > > > > > > > Allocating 3 vq groups as net is the device that need the most
> > > > > > > > groups:
> > > > > > > > * Dataplane (guest passthrough)
> > > > > > > > * CVQ
> > > > > > > > * Shadowed vrings.
> > > > > > > >
> > > > > > > > Future versions of the series can include dynamic allocation of
> > > > > > > > the
> > > > > > > > groups array so VDUSE can declare more groups.
> > > > > > > >
> > > > > > > > Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> > > > > > > > ---
> > > > > > > > v1: Fix: Remove BIT_ULL(VIRTIO_S_*), as _S_ is already the bit
> > > > > > > > (Maxime)
> > > > > > > >
> > > > > > > > RFC v3:
> > > > > > > > * Increase VDUSE_MAX_VQ_GROUPS to 0xffff (Jason). It was set to
> > > > > > > > a lower
> > > > > > > > value to reduce memory consumption, but vqs are already
> > > > > > > > limited to
> > > > > > > > that value and userspace VDUSE is able to allocate that many
> > > > > > > > vqs.
> > > > > > > > * Remove the descs vq group capability as it will not be used
> > > > > > > > and we can
> > > > > > > > add it on top.
> > > > > > > > * Do not ask for vq groups in number of vq groups < 2.
> > > > > > > > * Move the valid vq groups range check to vduse_validate_config.
> > > > > > > >
> > > > > > > > RFC v2:
> > > > > > > > * Cache group information in kernel, as we need to provide the
> > > > > > > > vq map
> > > > > > > > tokens properly.
> > > > > > > > * Add descs vq group to optimize SVQ forwarding and support
> > > > > > > > indirect
> > > > > > > > descriptors out of the box.
> > > > > > > > ---
> > > > > > > > drivers/vdpa/vdpa_user/vduse_dev.c | 51
> > > > > > > > ++++++++++++++++++++++++++++--
> > > > > > > > include/uapi/linux/vduse.h | 21 +++++++++++-
> > > > > > > > 2 files changed, 68 insertions(+), 4 deletions(-)
> > > > > > > >
> > > > > > > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > index e7bced0b5542..0f4e36dd167e 100644
> > > > > > > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > > > > > > @@ -58,6 +58,7 @@ struct vduse_virtqueue {
> > > > > > > > struct vdpa_vq_state state;
> > > > > > > > bool ready;
> > > > > > > > bool kicked;
> > > > > > > > + u32 vq_group;
> > > > > > > > spinlock_t kick_lock;
> > > > > > > > spinlock_t irq_lock;
> > > > > > > > struct eventfd_ctx *kickfd;
> > > > > > > > @@ -114,6 +115,7 @@ struct vduse_dev {
> > > > > > > > u8 status;
> > > > > > > > u32 vq_num;
> > > > > > > > u32 vq_align;
> > > > > > > > + u32 ngroups;
> > > > > > > > struct vduse_umem *umem;
> > > > > > > > struct mutex mem_lock;
> > > > > > > > unsigned int bounce_size;
> > > > > > > > @@ -592,6 +594,13 @@ static int vduse_vdpa_set_vq_state(struct
> > > > > > > > vdpa_device *vdpa, u16 idx,
> > > > > > > > return 0;
> > > > > > > > }
> > > > > > > >
> > > > > > > > +static u32 vduse_get_vq_group(struct vdpa_device *vdpa, u16
> > > > > > > > idx)
> > > > > > > > +{
> > > > > > > > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > +
> > > > > > > > + return dev->vqs[idx]->vq_group;
> > > > > > > > +}
> > > > > > > > +
> > > > > > > > static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa,
> > > > > > > > u16 idx,
> > > > > > > > struct vdpa_vq_state *state)
> > > > > > > > {
> > > > > > > > @@ -678,6 +687,28 @@ static u8 vduse_vdpa_get_status(struct
> > > > > > > > vdpa_device *vdpa)
> > > > > > > > return dev->status;
> > > > > > > > }
> > > > > > > >
> > > > > > > > +static int vduse_fill_vq_groups(struct vduse_dev *dev)
> > > > > > > > +{
> > > > > > > > + /* All vqs and descs must be in vq group 0 if ngroups <
> > > > > > > > 2 */
> > > > > > > > + if (dev->ngroups < 2)
> > > > > > > > + return 0;
> > > > > > > > +
> > > > > > > > + for (int i = 0; i < dev->vdev->vdpa.nvqs; ++i) {
> > > > > > > > + struct vduse_dev_msg msg = { 0 };
> > > > > > > > + int ret;
> > > > > > > > +
> > > > > > > > + msg.req.type = VDUSE_GET_VQ_GROUP;
> > > > > > > > + msg.req.vq_group.index = i;
> > > > > > > > + ret = vduse_dev_msg_sync(dev, &msg);
> > > > > > > > + if (ret)
> > > > > > > > + return ret;
> > > > > > > > +
> > > > > > > > + dev->vqs[i]->vq_group = msg.resp.vq_group.group;
> > > > > > > > + }
> > > > > > > > +
> > > > > > > > + return 0;
> > > > > > > > +}
> > > > > > > > +
> > > > > > > > static void vduse_vdpa_set_status(struct vdpa_device *vdpa, u8
> > > > > > > > status)
> > > > > > > > {
> > > > > > > > struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > > > > > > > @@ -685,6 +716,11 @@ static void vduse_vdpa_set_status(struct
> > > > > > > > vdpa_device *vdpa, u8 status)
> > > > > > > > if (vduse_dev_set_status(dev, status))
> > > > > > > > return;
> > > > > > > >
> > > > > > > > + if (((dev->status ^ status) &
> > > > > > > > VIRTIO_CONFIG_S_FEATURES_OK) &&
> > > > > > > > + (status & VIRTIO_CONFIG_S_FEATURES_OK))
> > > > > > > > + if (vduse_fill_vq_groups(dev))
> > > > > > > > + return;
> > > > > > >
> > > > > > > I may lose some context but I think we've agreed that we need to
> > > > > > > extend the status response for this instead of having multiple
> > > > > > > indepdent response.
> > > > > > >
> > > > > >
> > > > > > My understanding was it is ok to start with this version by [1]. We
> > > > > > can even make it asynchronous on top if we find this is a bottleneck
> > > > > > and the VDUSE device would need no change, would that work?
> > > > >
> > > > > I think I need to understand why we can not defer this to
> > > > > get_group_asid() call.
> > > > >
> > > >
> > > > Because we need to know the vq_groups->asid mapping in other calls
> > > > like set_group_asid or get_vq_group.
> > >
> > > I think we don't need the mapping of those, or anything I miss?
> > >
> >
> > If the kernel module does not ask the userland device for the actual
> > vq group of a virtqueue, what should it return in vduse_get_vq_group?
> > 0 for all vqs, even if the CVQ is in vq group 1?
>
> Since the topology is fixed I think userspace should provide this when
> creating a device.
>
> >
> > That's also valid for vduse_get_vq_map, which return is assumed not to
> > change in all the life of the device as it is not protected by a
> > mutex.
> >
> > > And the vq to group mappings could be piggy backed by the device
> > > creation request.
> > >
> >
> > I'm not sure, I think it involves a vduse request per asid or vq group
> > operation. Even get_vq_map. But I'm open to explore this possibility
> > for sure.
>
> Something like this?
>
> struct vduse_vq_config {
> __u32 index;
> __u16 max_size;
> __u16 reserved[13];
> };
I meant this actually:
struct vduse_vq_config {
__u32 index;
__u16 max_size;
__u16 group;
__u16 reserved[12];
};
Thanks
>
> ?
>
> Thanks
>
> >
> > > >
> > > > We could add a boolean on each virtqueue to track if we know its
> > > > virtqueue group and then only ask VDUSE device it if needed, would
> > > > that work?
> > >
> > > Thanks
> > >
> > > >
> > >
> >
