Re: [PATCH v2 00/19] Control VQ support in vDPA

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, May 09, 2022 at 11:42:10AM +0800, Jason Wang wrote:
> On Thu, Mar 31, 2022 at 2:05 AM Gautam Dawar <gautam.dawar@xilinx.com> wrote:
> >
> > Hi All:
> >
> > This series tries to add the support for control virtqueue in vDPA.
> >
> > Control virtqueue is used by networking device for accepting various
> > commands from the driver. It's a must to support multiqueue and other
> > configurations.
> >
> > When used by vhost-vDPA bus driver for VM, the control virtqueue
> > should be shadowed via userspace VMM (Qemu) instead of being assigned
> > directly to Guest. This is because Qemu needs to know the device state
> > in order to start and stop device correctly (e.g for Live Migration).
> >
> > This requies to isolate the memory mapping for control virtqueue
> > presented by vhost-vDPA to prevent guest from accessing it directly.
> >
> > To achieve this, vDPA introduce two new abstractions:
> >
> > - address space: identified through address space id (ASID) and a set
> >                  of memory mapping in maintained
> > - virtqueue group: the minimal set of virtqueues that must share an
> >                  address space
> >
> > Device needs to advertise the following attributes to vDPA:
> >
> > - the number of address spaces supported in the device
> > - the number of virtqueue groups supported in the device
> > - the mappings from a specific virtqueue to its virtqueue groups
> >
> > The mappings from virtqueue to virtqueue groups is fixed and defined
> > by vDPA device driver. E.g:
> >
> > - For the device that has hardware ASID support, it can simply
> >   advertise a per virtqueue group.
> > - For the device that does not have hardware ASID support, it can
> >   simply advertise a single virtqueue group that contains all
> >   virtqueues. Or if it wants a software emulated control virtqueue, it
> >   can advertise two virtqueue groups, one is for cvq, another is for
> >   the rest virtqueues.
> >
> > vDPA also allow to change the association between virtqueue group and
> > address space. So in the case of control virtqueue, userspace
> > VMM(Qemu) may use a dedicated address space for the control virtqueue
> > group to isolate the memory mapping.
> >
> > The vhost/vhost-vDPA is also extend for the userspace to:
> >
> > - query the number of virtqueue groups and address spaces supported by
> >   the device
> > - query the virtqueue group for a specific virtqueue
> > - assocaite a virtqueue group with an address space
> > - send ASID based IOTLB commands
> >
> > This will help userspace VMM(Qemu) to detect whether the control vq
> > could be supported and isolate memory mappings of control virtqueue
> > from the others.
> >
> > To demonstrate the usage, vDPA simulator is extended to support
> > setting MAC address via a emulated control virtqueue.
> >
> > Please review.
> 
> Michael, this looks good to me, do you have comments on this?
> 
> Thanks


I'll merge this for next.

> >
> > Changes since RFC v2:
> >
> > - Fixed memory leak for asid 0 in vhost_vdpa_remove_as()
> > - Removed unnecessary NULL check for iotlb in vhost_vdpa_unmap() and
> >   changed its return type to void.
> > - Removed insignificant used_as member field from struct vhost_vdpa.
> > - Corrected the iommu parameter in call to vringh_set_iotlb() from
> >   vdpasim_set_group_asid()
> > - Fixed build errors with vdpa_sim_net
> > - Updated alibaba, vdpa_user and virtio_pci vdpa parent drivers to
> >   call updated vDPA APIs and ensured successful build
> > - Tested control (MAC address configuration) and data-path using
> >   single virtqueue pair on Xilinx (now AMD) SN1022 SmartNIC device
> >   and vdpa_sim_net software device using QEMU release at [1]
> > - Removed two extra blank lines after set_group_asid() in
> >   include/linux/vdpa.h
> >
> > Changes since v1:
> >
> > - Rebased the v1 patch series on vhost branch of MST vhost git repo
> >   git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost
> > - Updates to accommodate vdpa_sim changes from monolithic module in
> >   kernel used v1 patch series to current modularized class (net, block)
> >   based approach.
> > - Added new attributes (ngroups and nas) to "vdpasim_dev_attr" and
> >   propagated them from vdpa_sim_net to vdpa_sim
> > - Widened the data-type for "asid" member of vhost_msg_v2 to __u32
> >   to accommodate PASID
> > - Fixed the buildbot warnings
> > - Resolved all checkpatch.pl errors and warnings
> > - Tested both control and datapath with Xilinx Smartnic SN1000 series
> >   device using QEMU implementing the Shadow virtqueue and support for
> >   VQ groups and ASID available at [1]
> >
> > Changes since RFC:
> >
> > - tweak vhost uAPI documentation
> > - switch to use device specific IOTLB really in patch 4
> > - tweak the commit log
> > - fix that ASID in vhost is claimed to be 32 actually but 16bit
> >   actually
> > - fix use after free when using ASID with IOTLB batching requests
> > - switch to use Stefano's patch for having separated iov
> > - remove unused "used_as" variable
> > - fix the iotlb/asid checking in vhost_vdpa_unmap()
> >
> > [1] Development QEMU release with support for SVQ, VQ groups and ASID:
> >   github.com/eugpermar/qemu/releases/tag/vdpa_sw_live_migration.d%2F
> >   asid_groups-v1.d%2F00
> >
> > Thanks
> >
> > Gautam Dawar (19):
> >   vhost: move the backend feature bits to vhost_types.h
> >   virtio-vdpa: don't set callback if virtio doesn't need it
> >   vhost-vdpa: passing iotlb to IOMMU mapping helpers
> >   vhost-vdpa: switch to use vhost-vdpa specific IOTLB
> >   vdpa: introduce virtqueue groups
> >   vdpa: multiple address spaces support
> >   vdpa: introduce config operations for associating ASID to a virtqueue
> >     group
> >   vhost_iotlb: split out IOTLB initialization
> >   vhost: support ASID in IOTLB API
> >   vhost-vdpa: introduce asid based IOTLB
> >   vhost-vdpa: introduce uAPI to get the number of virtqueue groups
> >   vhost-vdpa: introduce uAPI to get the number of address spaces
> >   vhost-vdpa: uAPI to get virtqueue group id
> >   vhost-vdpa: introduce uAPI to set group ASID
> >   vhost-vdpa: support ASID based IOTLB API
> >   vdpa_sim: advertise VIRTIO_NET_F_MTU
> >   vdpa_sim: factor out buffer completion logic
> >   vdpa_sim: filter destination mac address
> >   vdpasim: control virtqueue support
> >
> >  drivers/vdpa/alibaba/eni_vdpa.c      |   2 +-
> >  drivers/vdpa/ifcvf/ifcvf_main.c      |   8 +-
> >  drivers/vdpa/mlx5/net/mlx5_vnet.c    |  11 +-
> >  drivers/vdpa/vdpa.c                  |   5 +
> >  drivers/vdpa/vdpa_sim/vdpa_sim.c     | 100 ++++++++--
> >  drivers/vdpa/vdpa_sim/vdpa_sim.h     |   3 +
> >  drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 169 +++++++++++++----
> >  drivers/vdpa/vdpa_user/vduse_dev.c   |   3 +-
> >  drivers/vdpa/virtio_pci/vp_vdpa.c    |   2 +-
> >  drivers/vhost/iotlb.c                |  23 ++-
> >  drivers/vhost/vdpa.c                 | 267 +++++++++++++++++++++------
> >  drivers/vhost/vhost.c                |  23 ++-
> >  drivers/vhost/vhost.h                |   4 +-
> >  drivers/virtio/virtio_vdpa.c         |   2 +-
> >  include/linux/vdpa.h                 |  44 ++++-
> >  include/linux/vhost_iotlb.h          |   2 +
> >  include/uapi/linux/vhost.h           |  26 ++-
> >  include/uapi/linux/vhost_types.h     |  11 +-
> >  18 files changed, 563 insertions(+), 142 deletions(-)
> >
> > --
> > 2.30.1
> >