[RFC PATCH for 8.1 0/6] Move ASID test to vhost-vdpa net initialization

Eugenio Pérez posted 6 patches 1 year ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20230317145542.347368-1-eperezma@redhat.com
Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>
There is a newer version of this series
include/hw/virtio/vhost-vdpa.h |   2 +
hw/virtio/vhost-vdpa.c         |  78 +++++++++----
net/vhost-vdpa.c               | 205 +++++++++++++++++++++++++++------
hw/virtio/trace-events         |   2 +-
4 files changed, 227 insertions(+), 60 deletions(-)
[RFC PATCH for 8.1 0/6] Move ASID test to vhost-vdpa net initialization
Posted by Eugenio Pérez 1 year ago
QEMU v8.0.0-rc0 is able to switch dynamically between vhost-vdpa passthrough
and SVQ mode as long as the net device does not have CVQ.  The net device
state followed (and migrated) by CVQ requires special care.

A pre-requisite to add CVQ to that framework is to determine if devices with
CVQ are migratable or not at initialization time.  The solution to it is to
always shadow only CVQ, and vq groups and ASID are used for that.

However, current qemu version only checks ASID at device start (as "driver set
DRIVER_OK status bit"), not at device initialization.  A check at
initialization time is required.  Otherwise, the guest would be able to set
and remove migration blockers at will [1].

This series is a requisite for migration of vhost-vdpa net devices with CVQ.
However it already makes sense by its own, as it reduces the number of ioctls
at migration time, decreasing the error paths there.

[1] https://lore.kernel.org/qemu-devel/2616f0cd-f9e8-d183-ea78-db1be4825d9c@redhat.com/

Eugenio Pérez (6):
  vdpa: Remove status in reset tracing
  vdpa: add vhost_vdpa_reset_status_fd
  vdpa: add vhost_vdpa_set_dev_features_fd
  vdpa: return errno in vhost_vdpa_get_vring_group error
  vdpa: move CVQ isolation check to net_init_vhost_vdpa
  vdpa: Cache cvq group in VhostVDPAState

 include/hw/virtio/vhost-vdpa.h |   2 +
 hw/virtio/vhost-vdpa.c         |  78 +++++++++----
 net/vhost-vdpa.c               | 205 +++++++++++++++++++++++++++------
 hw/virtio/trace-events         |   2 +-
 4 files changed, 227 insertions(+), 60 deletions(-)

-- 
2.31.1