drm/amdkfd: preserve VRAM MQD across hibernation via unpin/repin

On gfx9 ASICs with mqd_on_vram(), a compute queue MQD lives in a pinned
VRAM buffer object. Pinned BOs are skipped by the VRAM eviction done at S4
suspend, so the MQD contents are lost across hibernation and the first
submission after resume page-faults on a stale MQD.

Unpin the MQD BO at suspend so the eviction migrates it into the
hibernation image, and pin it back to VRAM on resume. The BO may return at
a different VRAM address, so refresh the kernel mapping and cached GPU
addresses and patch the MQD self-address via a new update_mqd_gpu_addr()
mqd_manager op; skip eviction with a warning if that op is not implemented.

v3: use unpin/repin instead of shadowing the MQD into a separate buffer.

v4: drop the explicit VRAM->GTT placement at evict (a bare unpin is enough
for the eviction pass to move the BO out of VRAM), and also repin at queue
destroy. KFD queue restore runs late - user processes thaw before it, and
under SR-IOV it is deferred until the VF exits full access - so once the
VM has resumed an application can destroy a queue before its MQD BO is
repinned, which would otherwise unpin an already-unpinned BO and touch a
stale q->mqd.

v5: drop support for no-HWS mode, and set q->mqd to NULL at eviction.

Signed-off-by: Shikang Fan <shikang.fan@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

0 files changed, 0 insertions, 0 deletions