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drm/xe: Guard page-fault worker with runtime PM check

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During VM teardown, the VM's runtime PM reference is dropped
asynchronously, allowing the device to autosuspend while stale page
faults belonging to the now-dead VM are still queued. When the
page-fault worker later tries to ack one of these, it calls into
guc_ct_send_locked() on an already-suspended device, tripping:

  Assertion `!xe_pm_runtime_suspended(xe)` failed!
  WARNING at xe_device.c:1267 xe_device_assert_mem_access+0x11c/0x140 [xe]

A live VM/exec queue always holds a PM reference while it has
outstanding work, so if the device is suspended at ack time, the
owning context is already gone and the fault is stale.

Take a runtime PM reference across the entire pagefault
queue worker to safely deliver acks for torn-down VMs.

v3:
 - Move PM ref to the generic xe_pagefault_queue_work using
   guard(xe_pm_runtime)(xe) instead of tracking it in the GuC
   backend(Matt Brost).

v2:
 - Hold PM ref across the entire batch (begin/end) instead of per-ack.
   This prevents the device from autosuspending mid-batch, which would
   leave write_only acks written but the end flush skipped, and skip
   counter++, desyncing the cadence check.(Himal)
 - Add a comment explaining stale faults.(Himal)

Fixes: f289f78071 ("drm/xe: Add xe_guc_pagefault layer")
Signed-off-by: Varun Gupta <varun.gupta@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Link: https://patch.msgid.link/20260907050011.497181-2-varun.gupta@intel.com
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
(cherry picked from commit fcc2431d2213dc4d04250c4f1ae87d9c3ae0d455)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
[Rodrigo: Added xe_device struct for compatibility while cherry-picking]
This commit is contained in:
Varun Gupta 2026-09-07 10:30:12 +05:30 committed by Rodrigo Vivi
parent df2908090c
commit 20fce5b34b
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2 changed files with 13 additions and 0 deletions
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10
drivers/gpu/drm/xe/xe_pagefault.c
View File

@ -16,6 +16,7 @@
#include "xe_hw_engine.h"
#include "xe_pagefault.h"
#include "xe_pagefault_types.h"
#include "xe_pm.h"
#include "xe_svm.h"
#include "xe_trace_bo.h"
#include "xe_vm.h"
@ -292,9 +293,17 @@ static void xe_pagefault_queue_work(struct work_struct *w)
{
struct xe_pagefault_queue *pf_queue =
container_of(w, typeof(*pf_queue), worker);
struct xe_device *xe = pf_queue->xe;
struct xe_pagefault pf;
unsigned long threshold;
/*
* A live VM holds a PM reference, but a torn-down VM does not.
* Guard the entire worker loop to safely drain stale faults and
* prevent autosuspends from desyncing batched CT flushes.
*/
guard(xe_pm_runtime)(xe);
#define USM_QUEUE_MAX_RUNTIME_MS 20
threshold = jiffies + msecs_to_jiffies(USM_QUEUE_MAX_RUNTIME_MS);
@ -365,6 +374,7 @@ static int xe_pagefault_queue_init(struct xe_device *xe,
drm_dbg(&xe->drm, "xe_pagefault_entry_size=%d, total_num_eus=%d, pf_queue->size=%u",
xe_pagefault_entry_size(), total_num_eus, pf_queue->size);
pf_queue->xe = xe;
spin_lock_init(&pf_queue->lock);
INIT_WORK(&pf_queue->worker, xe_pagefault_queue_work);

3
drivers/gpu/drm/xe/xe_pagefault_types.h
View File

@ -8,6 +8,7 @@
#include <linux/workqueue.h>
struct xe_device;
struct xe_gt;
struct xe_pagefault;
@ -118,6 +119,8 @@ struct xe_pagefault {
* queue to absorb the device’s worst-case number of outstanding faults.
*/
struct xe_pagefault_queue {
/** @xe: Back-pointer to the Xe device */
struct xe_device *xe;
/**
* @data: Data in queue containing struct xe_pagefault, protected by
* @lock