drm/amdgpu: Implement UALink handle import ioctl

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The ualink handle import process involves NPA protocol
message exchange between the exporting and the importing
GPUs in the rack scale setup. The process is as follows:
1. On the importing GPU, check if connection is already setup
   with the exporting GPU. If not, then exchange HELLO/HELLO_ACK
   messages to setup the connection.
2. Once the connection is setup, then exchange NPA-REQ/NPA-RSP
   messages with the exporter GPU to get the NPA address and size
   of the BO associated with the ualink handle.
3. On the exporter GPU, upon receipt of NPA-REQ message, do basic
   validation to check the ualink handle is valid. If not, send a
   NPA-FAIL message back. If its valid, then using the address
   allocator, allocate a NPA address, map it into the NPA VM and
   send back the address and size in the NPA-RSP to the importing GPU.
4. On the importer GPU, upon receipt of NPA-RSP message, allocate a NPA
   BO at the NPA address received in the NPA-RSP message.
5. Finally, generate the corresponding DMABuf for the NPA BO and return
   the dmabuf to user-space.
6. We are using refcount to keep track of the importer/exporter xarray
   entries. The cleanup functions for these are added in the subsequent
   patches.

Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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Mukul Joshi 2026-04-27 22:12:09 -04:00 • committed by Alex Deucher

parent 2b4c5569d8

commit a9a7035e2e

2 changed files with 973 additions and 0 deletions

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900

drivers/gpu/drm/amd/amdgpu/amdgpu_ualink.c

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73

drivers/gpu/drm/amd/amdgpu/amdgpu_ualink.h

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