drm/xe: Use xe_pm_runtime_get in xe_bo_move() if reclaim-safe.

xe_bo_move() might be called in the TTM swapout path from validation
by another TTM device. If so, we are not likely to have a RPM
reference. So iff xe_pm_runtime_get() is safe to call from reclaim,
use it instead of xe_pm_runtime_get_noresume().

Strictly this is currently needed only if handle_system_ccs is true,
but use xe_pm_runtime_get() if possible anyway to increase test
coverage.

At the same time warn if handle_system_ccs is true and we can't
call xe_pm_runtime_get() from reclaim context. This will likely trip
if someone tries to enable SRIOV on LNL, without fixing Xe SRIOV
runtime resume / suspend.

Cc: Rodrigo Vivi <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: Matthew Auld <[email protected]>
Signed-off-by: Thomas Hellström <[email protected]>
Reviewed-by: Matthew Auld <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: Thomas Hellström

drivers/gpu/drm/xe/xe_bo.c

@@ -758,7 +758,16 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict,
 
 	xe_assert(xe, migrate);
 	trace_xe_bo_move(bo, new_mem->mem_type, old_mem_type, move_lacks_source);
-	xe_pm_runtime_get_noresume(xe);
+	if (xe_rpm_reclaim_safe(xe)) {
+		/*
+		 * We might be called through swapout in the validation path of
+		 * another TTM device, so unconditionally acquire rpm here.
+		 */
+		xe_pm_runtime_get(xe);
+	} else {
+		drm_WARN_ON(&xe->drm, handle_system_ccs);
+		xe_pm_runtime_get_noresume(xe);
+	}
 
 	if (xe_bo_is_pinned(bo) && !xe_bo_is_user(bo)) {
 		/*

drivers/gpu/drm/xe/xe_pm.c

@@ -79,7 +79,14 @@ static struct lockdep_map xe_pm_runtime_nod3cold_map = {
 };
 #endif
 
-static bool __maybe_unused xe_rpm_reclaim_safe(const struct xe_device *xe)
+/**
+ * xe_rpm_reclaim_safe() - Whether runtime resume can be done from reclaim context
+ * @xe: The xe device.
+ *
+ * Return: true if it is safe to runtime resume from reclaim context.
+ * false otherwise.
+ */
+bool xe_rpm_reclaim_safe(const struct xe_device *xe)
 {
 	return !xe->d3cold.capable && !xe->info.has_sriov;
 }

drivers/gpu/drm/xe/xe_pm.h

@@ -31,6 +31,7 @@ bool xe_pm_runtime_resume_and_get(struct xe_device *xe);
 void xe_pm_assert_unbounded_bridge(struct xe_device *xe);
 int xe_pm_set_vram_threshold(struct xe_device *xe, u32 threshold);
 void xe_pm_d3cold_allowed_toggle(struct xe_device *xe);
+bool xe_rpm_reclaim_safe(const struct xe_device *xe);
 struct task_struct *xe_pm_read_callback_task(struct xe_device *xe);
 int xe_pm_module_init(void);