Re: [PATCH v8 03/28] vfio/container: support VFIO_DMA_UNMAP_FLAG_ALL

[John Levon <levon@movementarian.org>]

On Wed, Apr 02, 2025 at 06:49:50PM +0200, Cédric Le Goater wrote:

> On 2/19/25 15:48, John Levon wrote:
> > Some containers can directly implement unmapping all regions;
> > add a new flag to support this.
> > 
> > Originally-by: John Johnson <john.g.johnson@oracle.com>
> > Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> > Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> > Signed-off-by: John Levon <john.levon@nutanix.com>
> > ---
> >   hw/vfio/common.c                      | 24 +++++++----------
> >   hw/vfio/container-base.c              |  4 +--
> >   hw/vfio/container.c                   | 38 +++++++++++++++++++++++++--
> >   hw/vfio/iommufd.c                     | 19 +++++++++++++-
> >   include/hw/vfio/vfio-common.h         |  1 +
> >   include/hw/vfio/vfio-container-base.h |  4 +--
> >   6 files changed, 68 insertions(+), 22 deletions(-)
> 
> This is difficult to understand. There are no functional changes right ?

+    ret = ioctl(container->fd, VFIO_CHECK_EXTENSION, VFIO_UNMAP_ALL);

This is new, we previously never even tried to use this.

> I think it should be broken down further to clarify the changes.

patch 1: add a flags param to the callbacks, always zero
patch 2: pass through unmap all flag to callbacks
patch 3: check for unmap_all extension and use it

That sound better?

regards
john