Re: [PATCH 0/2] drm/xe: support VM sharing between apps

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

Hi, Moti



On Tue, 2024-02-06 at 16:18 +0200, Moti Haimovski wrote:
> This first patch set introduces support for sharing a VM (or context)
> between
> applications that use different resources on the same Xe device.
> 
> The first patch adds a refcount to the VM in order support managing
> it by
> multiple users/apps.
> 
> The second patch exports the VM as a FD in order to allow other apps
> to use it.
> 
> Follow-up series will include the driver code to provide full
> functionality for
> this feature.
> 
> Bharat Jauhari (1):
>   drm/xe: support to export VM as fd
> 
> Moti Haimovski (1):
>   drm/xe: add ref count to xe_file
> 
>  drivers/gpu/drm/xe/xe_device.c       |  52 ++++++++++--
>  drivers/gpu/drm/xe/xe_device.h       |   6 ++
>  drivers/gpu/drm/xe/xe_device_types.h |   3 +
>  drivers/gpu/drm/xe/xe_vm.c           | 121
> +++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_vm.h           |   2 +
>  drivers/gpu/drm/xe/xe_vm_types.h     |  28 +++++++
>  include/uapi/drm/xe_drm.h            |  27 ++++++
>  7 files changed, 232 insertions(+), 7 deletions(-)
> 

Do we have any user-space drivers or applications available for review
that exercises this? (We must have for the uAPI changes before pushing
to drm-xe-next)

On the refcount to xe_file, I see that as a bit dangerous. If the
xe_file is alive but the file closed, I figure that opens up for hard-
to-track-down problems. Is there a way we could look at refcounting at
a lower level?

/Thomas