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

[Michael S. Tsirkin]

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?

> 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
>