[PATCH 0/1] drm/amdkfd: Fix SVM page migration hang on MES-based GPUs

[Priya Hosur <Priya.Hosur@amd.com>]

This patch addresses a GPU queue hang issue during SVM (Shared Virtual
Memory) page migration on MES-based GPUs, specifically observed on
gfx1151 (Ryzen AI MAX).

Problem:
--------
KFDSVMRangeTest.MultiThreadMigrationTest/1 fails with a queue consumption
timeout when XNACK mode 1 is enabled. The GPU compute queue hangs with
packets submitted but never consumed.

Root Cause:
-----------
MES (Micro Engine Scheduler) does not perform heavy-weight TLB invalidation
after unmapping queues, unlike HWS which does this automatically. This
causes in-flight SDMA DMA descriptors to access memory that has been
unmapped, leading to page faults and queue hangs.

Fix:
----
Add kfd_flush_tlb() with TLB_FLUSH_HEAVYWEIGHT after MES removes/suspends
queues in evict_process_queues_cpsch() and suspend_queues().

Testing:
--------
Platform: gfx1151, ROCm 7.15.0, kernel 7.0.0-28-generic

Results:
  - Baseline (no fix):     100% failure (50 runs)
  - With TLB flush:        7-10% failure (100 runs)

The TLB flush significantly reduces failures from 100% to ~10%. The
residual failures require further investigation and may be addressed
in a follow-up patch.

Priya Hosur (1):
  drm/amdkfd: Add TLB flush after MES queue eviction/suspension

 .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.c   | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

-- 
2.43.0