linux-kernel - Re: [PATCH vhost v2 00/16] vdpa: Add support for vq descriptor mappings

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Message-ID: <20231005151812-mutt-send-email-mst@kernel.org>
Date:   Thu, 5 Oct 2023 15:18:25 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Dragos Tatulea <dtatulea@...dia.com>
Cc:     "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "xuanzhuo@...ux.alibaba.com" <xuanzhuo@...ux.alibaba.com>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        Gal Pressman <gal@...dia.com>,
        "eperezma@...hat.com" <eperezma@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "leon@...nel.org" <leon@...nel.org>,
        Saeed Mahameed <saeedm@...dia.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH vhost v2 00/16] vdpa: Add support for vq descriptor
 mappings

On Thu, Oct 05, 2023 at 05:44:01PM +0000, Dragos Tatulea wrote:
> On Thu, 2023-10-05 at 13:31 -0400, Michael S. Tsirkin wrote:
> > On Thu, Sep 28, 2023 at 07:45:11PM +0300, Dragos Tatulea wrote:
> > > This patch series adds support for vq descriptor table mappings which
> > > are used to improve vdpa live migration downtime. The improvement comes
> > > from using smaller mappings which take less time to create and destroy
> > > in hw.
> > > 
> > > The first part adds the vdpa core changes from Si-Wei [0].
> > > 
> > > The second part adds support in mlx5_vdpa:
> > > - Refactor the mr code to be able to cleanly add descriptor mappings.
> > > - Add hardware descriptor mr support.
> > > - Properly update iotlb for cvq during ASID switch.
> > > 
> > > Changes in v2:
> > > 
> > > - The "vdpa/mlx5: Enable hw support for vq descriptor mapping" change
> > >   was split off into two patches to avoid merge conflicts into the tree
> > >   of Linus.
> > > 
> > >   The first patch contains only changes for mlx5_ifc.h. This must be
> > >   applied into the mlx5-next tree [1] first. Once this patch is applied
> > >   on mlx5-next, the change has to be pulled fom mlx5-next into the vhost
> > >   tree and only then the remaining patches can be applied.
> > 
> > 
> > I get it you plan v3?
> There are some very small improvements (commit message in 13/16 and fix in
> 16/16) that could make a v3. The latter can be addressed as a separate patch
> when moving dup_iotlb to vhost/iotlb. What do you think?


if there's a fix by all means post v3.

> > 
> > > [0]
> > > https://lore.kernel.org/virtualization/1694248959-13369-1-git-send-email-si-wei.liu@oracle.com
> > > [1]
> > > https://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.git/log/?h=mlx5-next
> > > 
> > > Dragos Tatulea (13):
> > >   vdpa/mlx5: Expose descriptor group mkey hw capability
> > >   vdpa/mlx5: Create helper function for dma mappings
> > >   vdpa/mlx5: Decouple cvq iotlb handling from hw mapping code
> > >   vdpa/mlx5: Take cvq iotlb lock during refresh
> > >   vdpa/mlx5: Collapse "dvq" mr add/delete functions
> > >   vdpa/mlx5: Rename mr destroy functions
> > >   vdpa/mlx5: Allow creation/deletion of any given mr struct
> > >   vdpa/mlx5: Move mr mutex out of mr struct
> > >   vdpa/mlx5: Improve mr update flow
> > >   vdpa/mlx5: Introduce mr for vq descriptor
> > >   vdpa/mlx5: Enable hw support for vq descriptor mapping
> > >   vdpa/mlx5: Make iotlb helper functions more generic
> > >   vdpa/mlx5: Update cvq iotlb mapping on ASID change
> > > 
> > > Si-Wei Liu (3):
> > >   vdpa: introduce dedicated descriptor group for virtqueue
> > >   vhost-vdpa: introduce descriptor group backend feature
> > >   vhost-vdpa: uAPI to get dedicated descriptor group id
> > > 
> > >  drivers/vdpa/mlx5/core/mlx5_vdpa.h |  31 +++--
> > >  drivers/vdpa/mlx5/core/mr.c        | 191 ++++++++++++++++-------------
> > >  drivers/vdpa/mlx5/core/resources.c |   6 +-
> > >  drivers/vdpa/mlx5/net/mlx5_vnet.c  | 100 ++++++++++-----
> > >  drivers/vhost/vdpa.c               |  27 ++++
> > >  include/linux/mlx5/mlx5_ifc.h      |   8 +-
> > >  include/linux/mlx5/mlx5_ifc_vdpa.h |   7 +-
> > >  include/linux/vdpa.h               |  11 ++
> > >  include/uapi/linux/vhost.h         |   8 ++
> > >  include/uapi/linux/vhost_types.h   |   5 +
> > >  10 files changed, 264 insertions(+), 130 deletions(-)
> > > 
> > > -- 
> > > 2.41.0
> > 
>