[Intel-xe] [PATCH] drm/xe: Disallow pinning dma-bufs in VRAM

[Thomas Hellström]

On 9/20/23 11:35, Oded Gabbay wrote:
> On Tue, Sep 19, 2023 at 11:46 AM Thomas Hellström
> <thomas.hellstrom at linux.intel.com> wrote:
>> For now only support pinning in TT memory, for two reasons:
>> 1) Avoid pinning in a placement not accessible to some importers.
>> 2) Pinning in VRAM requires PIN accounting which is a to-do.
>>
>> Suggested-by: Oded Gabbay <ogabbay at kernel.org>
>> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>> ---
>>   drivers/gpu/drm/xe/xe_dma_buf.c | 25 +++++++++++++++++++++----
>>   1 file changed, 21 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c
>> index 09343b8b3e96..bd8d51e7f93f 100644
>> --- a/drivers/gpu/drm/xe/xe_dma_buf.c
>> +++ b/drivers/gpu/drm/xe/xe_dma_buf.c
>> @@ -49,13 +49,30 @@ static int xe_dma_buf_pin(struct dma_buf_attachment *attach)
>>   {
>>          struct drm_gem_object *obj = attach->dmabuf->priv;
>>          struct xe_bo *bo = gem_to_xe_bo(obj);
>> +       struct xe_device *xe = xe_bo_device(bo);
>> +       int ret;
>>
>>          /*
>> -        * Migrate to TT first to increase the chance of non-p2p clients
>> -        * can attach.
>> +        * For now only support pinning in TT memory, for two reasons:
>> +        * 1) Avoid pinning in a placement not accessible to some importers.
>> +        * 2) Pinning in VRAM requires PIN accounting which is a to-do.
>>           */
>> -       (void)xe_bo_migrate(bo, XE_PL_TT);
>> -       xe_bo_pin_external(bo);
>> +       if (xe_bo_is_pinned(bo) && bo->ttm.resource->placement != XE_PL_TT) {
>> +               drm_dbg(&xe->drm, "Can't migrate pinned bo for dma-buf pin.\n");
>> +               return -EINVAL;
>> +       }
>> +
>> +       ret = xe_bo_migrate(bo, XE_PL_TT);
>> +       if (ret) {
>> +               if (ret != -EINTR && ret != -ERESTARTSYS)
>> +                       drm_dbg(&xe->drm,
>> +                               "Failed migrating dma-buf to TT memory: %pe\n",
>> +                               ERR_PTR(ret));
>> +               return ret;
>> +       }
>> +
>> +       ret = xe_bo_pin_external(bo);
>> +       xe_assert(xe, !ret);
>>
>>          return 0;
>>   }
>> --
>> 2.41.0
>>
> Reviewed-by: Oded Gabbay <ogabbay at kernel.org>

Thanks for revieiwing, Oded. Just sent a v2 with a kunit test update to 
reflect the changes. Please let me know if there are any issues with that.

/Thomas

> Thanks,
> Oded