[PATCH] drm/xe/pm: do not warn about missing runtime PM protection after hot-unplug

[Nitin Gote <nitin.r.gote@intel.com>]

Exec queues are owned by user fds and are destroyed when the fd is closed.
After hot-unplug this can happen from a deferred close during process
exit, after the device has been removed and runtime PM has been disabled.
The queue destroy path can call xe_pm_runtime_get_noresume(), and since
runtime PM is disabled pm_runtime_get_if_in_use() returns no reference,
so it warns about "Missing outer runtime PM protection".

This is a false positive for the hot-unplug teardown case. The device is
already unplugged, and the queue destroy path that triggered this warning
was checked and does not touch hardware state after unplug. GuC has already
been sanitized by guc_fini_hw(), so no H2G is sent and the hardware
teardown path is no longer reachable.

Skip the warning when the DRM device is already unplugged.

Observed with new IGT core_hotunplug subtests:
  igt@core_hotunplug@hotreplug-with-load
  igt@core_hotunplug@hotunplug-rescan-with-load

v2:
 - Drop the drm_dev_is_unplugged() bypass from guc_exec_queue_destroy()
   and instead exclude hot-unplug from the WARN in
   xe_pm_runtime_get_noresume(). (Matthew Brost)

v3:
 - Clarify that the queue destroy path was checked and does not touch
   hardware state after unplug. (Matthew Auld)

Link: https://patchwork.freedesktop.org/patch/725773/?series=166744&rev=4
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Assisted-by: GitHub-Copilot:claude-opus-4.8
Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
---
 drivers/gpu/drm/xe/xe_pm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
index a5289a9df8d2..a038687d5b2c 100644
--- a/drivers/gpu/drm/xe/xe_pm.c
+++ b/drivers/gpu/drm/xe/xe_pm.c
@@ -10,6 +10,7 @@
 #include <linux/suspend.h>
 #include <linux/dmi.h>
 
+#include <drm/drm_drv.h>
 #include <drm/drm_managed.h>
 #include <drm/ttm/ttm_placement.h>
 
@@ -914,7 +915,9 @@ void xe_pm_runtime_get_noresume(struct xe_device *xe)
 
 	if (!ref) {
 		pm_runtime_get_noresume(xe->drm.dev);
-		drm_WARN(&xe->drm, !xe_pm_suspending_or_resuming(xe),
+		drm_WARN(&xe->drm,
+			 !drm_dev_is_unplugged(&xe->drm) &&
+			 !xe_pm_suspending_or_resuming(xe),
 			 "Missing outer runtime PM protection\n");
 	}
 }
-- 
2.50.1