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drm/xe/lrc: fix spurious warning when reading context timestamp

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Fixes the following warning that fires during timeout handling for a
context running on the USM-reserved copy engine:

  xe 0000:03:00.0: [drm] Tile0: GT0: Unexpected engine class:instance 3:8 for utilization
  WARNING: at engine_id_to_hwe+0x88/0xc0 [xe]
    xe_lrc_context_timestamp+0x61/0xb0 [xe]
    guc_exec_queue_timedout_job+0x713/0x1020 [xe]

class:instance 3:8 is XE_ENGINE_CLASS_COPY on the highest BCS instance,
which xe_hw_engine.c reserves for USM (gt->usm.reserved_bcs_instance) and
on which the migrate engine runs kernel contexts. When such a context's
utilization is read - e.g. from the TDR path - engine_id_to_hwe()
rejected it because xe_hw_engine_is_reserved() is true, firing WARN_ONCE
and returning NULL, which made the timestamp read silently fall back to
stale data.

The reserved-engine guard was added defensively with the original WA BB
utilization support and simply overlooked that the migrate engine is a
valid, present engine whose CTX_TIMESTAMP can legitimately be read.

Allow the USM-reserved copy engine specifically (xe_gt_is_usm_hwe()),
while still rejecting the other reserved cases (GSCCS / XE_ENGINE_CLASS_
OTHER and ccs_mode-disabled compute engines), which would indeed be
unexpected on this path. The dynamic engine resolution via the ENGINE_ID
stashed in the PPHWSP by the WA BB is kept intact, so utilization for
load-balanced/virtual exec queues still resolves the engine the context
is actually running on.

Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Sanjay Yadav <sanjay.kumar.yadav@intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Assisted-by: GitHub-Copilot:claude-sonnet-4.6
Assisted-by: GitHub-Copilot:claude-opus-4.8
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patch.msgid.link/20260610152548.404575-4-rodrigo.vivi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Rodrigo Vivi 2026-06-10 11:25:50 -04:00
parent b1107d085e
commit 0cfa716f19
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1 changed files with 7 additions and 1 deletions
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8
drivers/gpu/drm/xe/xe_lrc.c
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@ -2618,13 +2618,19 @@ void xe_lrc_snapshot_free(struct xe_lrc_snapshot *snapshot)
kfree(snapshot);
}
static bool engine_valid_for_utilization(struct xe_gt *gt, struct xe_hw_engine *hwe)
{
/* The USM-reserved copy engine runs kernel migrate contexts queried here */
return hwe && (!xe_hw_engine_is_reserved(hwe) || xe_gt_is_usm_hwe(gt, hwe));
}
static struct xe_hw_engine *engine_id_to_hwe(struct xe_gt *gt, u32 engine_id)
{
u16 class = REG_FIELD_GET(ENGINE_CLASS_ID, engine_id);
u16 instance = REG_FIELD_GET(ENGINE_INSTANCE_ID, engine_id);
struct xe_hw_engine *hwe = xe_gt_hw_engine(gt, class, instance, false);
if (xe_gt_WARN_ONCE(gt, !hwe || xe_hw_engine_is_reserved(hwe),
if (xe_gt_WARN_ONCE(gt, !engine_valid_for_utilization(gt, hwe),
"Unexpected engine class:instance %d:%d for utilization\n",
class, instance))
return NULL;