Re: [PATCH v6 00/10] ASID support in vhost-vdpa net

[Eugenio Perez Martin]

On Thu, Nov 10, 2022 at 1:25 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Tue, Nov 08, 2022 at 06:07:45PM +0100, Eugenio Pérez wrote:
> > Control VQ is the way net devices use to send changes to the device state, 
> > like
> > the number of active queues or its mac address.
> >
> > QEMU needs to intercept this queue so it can track these changes and is 
> > able to
> > migrate the device. It can do it from 1576dbb5bbc4 ("vdpa: Add x-svq to
> > NetdevVhostVDPAOptions"). However, to enable x-svq implies to shadow all 
> > VirtIO
> > device's virtqueues, which will damage performance.
> >
> > This series adds address space isolation, so the device and the guest
> > communicate directly with them (passthrough) and CVQ communication is split 
> > in
> > two: The guest communicates with QEMU and QEMU forwards the commands to the
> > device.
> >
> > Comments are welcome. Thanks!
>
>
> This is not 7.2 material, right?
>

No it is not.

I should have noted it after PATCH in the subject, sorry.

> > v6:
> > - Do not allocate SVQ resources like file descriptors if SVQ cannot be used.
> > - Disable shadow CVQ if the device does not support it because of net
> >   features.
> >
> > v5:
> > - Move vring state in vhost_vdpa_get_vring_group instead of using a
> >   parameter.
> > - Rename VHOST_VDPA_NET_CVQ_PASSTHROUGH to VHOST_VDPA_NET_DATA_ASID
> >
> > v4:
> > - Rebased on last CVQ start series, that allocated CVQ cmd bufs at load
> > - Squash vhost_vdpa_cvq_group_is_independent.
> > - Do not check for cvq index on vhost_vdpa_net_prepare, we only have one
> >   that callback registered in that NetClientInfo.
> > - Add comment specifying behavior if device does not support _F_ASID
> > - Update headers to a later Linux commit to not to remove SETUP_RNG_SEED
> >
> > v3:
> > - Do not return an error but just print a warning if vdpa device 
> > initialization
> >   returns failure while getting AS num of VQ groups
> > - Delete extra newline
> >
> > v2:
> > - Much as commented on series [1], handle vhost_net backend through
> >   NetClientInfo callbacks instead of directly.
> > - Fix not freeing SVQ properly when device does not support CVQ
> > - Add BIT_ULL missed checking device's backend feature for _F_ASID.
> >
> > Eugenio Pérez (10):
> >   vdpa: Use v->shadow_vqs_enabled in vhost_vdpa_svqs_start & stop
> >   vhost: set SVQ device call handler at SVQ start
> >   vhost: Allocate SVQ device file descriptors at device start
> >   vdpa: add vhost_vdpa_net_valid_svq_features
> >   vdpa: move SVQ vring features check to net/
> >   vdpa: Allocate SVQ unconditionally
> >   vdpa: Add asid parameter to vhost_vdpa_dma_map/unmap
> >   vdpa: Store x-svq parameter in VhostVDPAState
> >   vdpa: Add listener_shadow_vq to vhost_vdpa
> >   vdpa: Always start CVQ in SVQ mode
> >
> >  include/hw/virtio/vhost-vdpa.h     |  10 +-
> >  hw/virtio/vhost-shadow-virtqueue.c |  35 +-----
> >  hw/virtio/vhost-vdpa.c             | 114 ++++++++++---------
> >  net/vhost-vdpa.c                   | 171 ++++++++++++++++++++++++++---
> >  hw/virtio/trace-events             |   4 +-
> >  5 files changed, 222 insertions(+), 112 deletions(-)
> >
> > --
> > 2.31.1
> >
>