On 2024-03-15 14:17, Mukul Joshi wrote:
Check cgroup permissions when returning DMA-buf info and
based on cgroup check return the id of the GPU that has
access to the BO.

Signed-off-by: Mukul Joshi <mukul.jo...@amd.com>
---
  drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c 
b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index dfa8c69532d4..f9631f4b1a02 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1523,7 +1523,7 @@ static int kfd_ioctl_get_dmabuf_info(struct file *filep,
/* Find a KFD GPU device that supports the get_dmabuf_info query */
        for (i = 0; kfd_topology_enum_kfd_devices(i, &dev) == 0; i++)
-               if (dev)
+               if (dev && !kfd_devcgroup_check_permission(dev))
                        break;
        if (!dev)
                return -EINVAL;
@@ -1545,7 +1545,7 @@ static int kfd_ioctl_get_dmabuf_info(struct file *filep,
        if (xcp_id >= 0)
                args->gpu_id = dmabuf_adev->kfd.dev->nodes[xcp_id]->id;
        else
-               args->gpu_id = dmabuf_adev->kfd.dev->nodes[0]->id;
+               args->gpu_id = dev->id;

If I remember correctly, this was meant as a fallback in case for GTT BOs where the exporting partition wasn't known and the application didn't have access to the first partition. I think the way you wrote this, it could also change the behaviour (report the wrong GPU ID) on single-partition GPUs, which is probably not intended. Maybe this would preserve the behaviour for that case:

        ...
-       else
+       else if 
(!kfd_devcgroup_check_permission(dmabuf_adev->kfd.dev->nodes[0]))
                args->gpu_id = dmabuf_adev->kfd.dev->nodes[0]->id;
+       else
+               args->gpu_id = dev->id;

Or maybe a more general solution would make DMABuf import work when the exporter is really unknown or not even a GPU. This came up not so long ago in the context of interop with 3rd-party devices. This may require user mode changes as well.

Regards,
  Felix


        args->flags = flags;
/* Copy metadata buffer to user mode */

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