[PATCH v4 4/4] drm/xe/vf: Defer fixups if migrated twice fast

[Tomasz Lis <tomasz.lis@intel.com>]

If another VF migration happened during post-migration recovery,
then the current worker should be finished to allow the next
one start swiftly and cleanly.

Check for defer in two places: before fixups, and before
sending RESFIX_DONE.

Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
---
 drivers/gpu/drm/xe/xe_sriov_vf.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.c b/drivers/gpu/drm/xe/xe_sriov_vf.c
index 97ab66edd711..1d4f278cb7a6 100644
--- a/drivers/gpu/drm/xe/xe_sriov_vf.c
+++ b/drivers/gpu/drm/xe/xe_sriov_vf.c
@@ -50,6 +50,19 @@ static int vf_post_migration_requery_guc(struct xe_device *xe)
 	return ret;
 }
 
+/*
+ * vf_post_migration_imminent - Check if post-restore recovery is coming.
+ * @xe: the &xe_device struct instance
+ *
+ * Return: True if migration recovery worker will soon be running. Any worker currently
+ * executing does not affect the result.
+ */
+static bool vf_post_migration_imminent(struct xe_device *xe)
+{
+	return xe->sriov.vf.migration.gt_flags != 0 ||
+	work_pending(&xe->sriov.vf.migration.worker);
+}
+
 /*
  * vf_post_migration_notify_resfix_done - Notify all GuCs about resource fixups apply finished.
  * @xe: the &xe_device struct instance
@@ -61,11 +74,17 @@ static void vf_post_migration_notify_resfix_done(struct xe_device *xe)
 	int err, num_sent = 0;
 
 	for_each_gt(gt, xe, id) {
+		if (vf_post_migration_imminent(xe))
+			goto skip;
 		err = xe_gt_sriov_vf_notify_resfix_done(gt);
 		if (!err)
 			num_sent++;
 	}
 	drm_dbg(&xe->drm, "sent %d VF resource fixups done notifications\n", num_sent);
+	return;
+
+skip:
+	drm_dbg(&xe->drm, "another recovery imminent, skipping notifications\n");
 }
 
 static void vf_post_migration_recovery(struct xe_device *xe)
@@ -75,6 +94,8 @@ static void vf_post_migration_recovery(struct xe_device *xe)
 	drm_dbg(&xe->drm, "migration recovery in progress\n");
 	xe_pm_runtime_get(xe);
 	err = vf_post_migration_requery_guc(xe);
+	if (vf_post_migration_imminent(xe))
+		goto defer;
 	if (unlikely(err))
 		goto fail;
 
@@ -83,6 +104,10 @@ static void vf_post_migration_recovery(struct xe_device *xe)
 	xe_pm_runtime_put(xe);
 	drm_notice(&xe->drm, "migration recovery ended\n");
 	return;
+defer:
+	xe_pm_runtime_put(xe);
+	drm_dbg(&xe->drm, "migration recovery deferred\n");
+	return;
 fail:
 	xe_pm_runtime_put(xe);
 	drm_err(&xe->drm, "migration recovery failed (%pe)\n", ERR_PTR(err));
-- 
2.25.1