drm/xe/pf: Expose VF migration data size over debugfs

The size is normally used to make a decision on when to stop the device
(mainly when it's in a pre_copy state).

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20251112132220.516975-10-michal.winiarski@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>

drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c

@@ -396,6 +396,27 @@ ssize_t xe_gt_sriov_pf_migration_write_guc_state(struct xe_gt *gt, unsigned int
 }
 #endif /* CONFIG_DEBUG_FS */
 
+/**
+ * xe_gt_sriov_pf_migration_size() - Total size of migration data from all components within a GT.
+ * @gt: the &xe_gt
+ * @vfid: the VF identifier (can't be 0)
+ *
+ * This function is for PF only.
+ *
+ * Return: total migration data size in bytes or a negative error code on failure.
+ */
+ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid)
+{
+	ssize_t total = 0;
+
+	xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
+	xe_gt_assert(gt, vfid != PFID);
+	xe_gt_assert(gt, vfid <= xe_sriov_pf_get_totalvfs(gt_to_xe(gt)));
+
+	/* Nothing to query yet - will be updated once per-GT migration data types are added */
+	return total;
+}
+
 /**
  * xe_gt_sriov_pf_migration_ring_empty() - Check if a migration ring is empty.
  * @gt: the &xe_gt

drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h

@@ -15,6 +15,8 @@ int xe_gt_sriov_pf_migration_init(struct xe_gt *gt);
 int xe_gt_sriov_pf_migration_save_guc_state(struct xe_gt *gt, unsigned int vfid);
 int xe_gt_sriov_pf_migration_restore_guc_state(struct xe_gt *gt, unsigned int vfid);
 
+ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid);
+
 bool xe_gt_sriov_pf_migration_ring_empty(struct xe_gt *gt, unsigned int vfid);
 bool xe_gt_sriov_pf_migration_ring_full(struct xe_gt *gt, unsigned int vfid);
 void xe_gt_sriov_pf_migration_ring_free(struct xe_gt *gt, unsigned int vfid);

drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c

@@ -284,6 +284,33 @@ static const struct file_operations data_vf_fops = {
 	.llseek		= default_llseek,
 };
 
+static ssize_t size_read(struct file *file, char __user *ubuf, size_t count, loff_t *ppos)
+{
+	struct dentry *dent = file_dentry(file)->d_parent;
+	struct xe_device *xe = extract_xe(dent);
+	unsigned int vfid = extract_vfid(dent);
+	char buf[21];
+	ssize_t ret;
+	int len;
+
+	xe_pm_runtime_get(xe);
+	ret = xe_sriov_pf_migration_size(xe, vfid);
+	xe_pm_runtime_put(xe);
+	if (ret < 0)
+		return ret;
+
+	len = scnprintf(buf, sizeof(buf), "%zd\n", ret);
+
+	return simple_read_from_buffer(ubuf, count, ppos, buf, len);
+}
+
+static const struct file_operations size_vf_fops = {
+	.owner		= THIS_MODULE,
+	.open		= simple_open,
+	.read		= size_read,
+	.llseek		= default_llseek,
+};
+
 static void pf_populate_vf(struct xe_device *xe, struct dentry *vfdent)
 {
 	debugfs_create_file("pause", 0200, vfdent, xe, &pause_vf_fops);
@@ -293,6 +320,7 @@ static void pf_populate_vf(struct xe_device *xe, struct dentry *vfdent)
 	debugfs_create_file("save", 0600, vfdent, xe, &save_vf_fops);
 	debugfs_create_file("restore", 0600, vfdent, xe, &restore_vf_fops);
 	debugfs_create_file("migration_data", 0600, vfdent, xe, &data_vf_fops);
+	debugfs_create_file("migration_size", 0400, vfdent, xe, &size_vf_fops);
 }
 
 static void pf_populate_with_tiles(struct xe_device *xe, struct dentry *dent, unsigned int vfid)

drivers/gpu/drm/xe/xe_sriov_pf_migration.c

@@ -310,3 +310,33 @@ ssize_t xe_sriov_pf_migration_write(struct xe_device *xe, unsigned int vfid,
 
 	return produced;
 }
+
+/**
+ * xe_sriov_pf_migration_size() - Total size of migration data from all components within a device
+ * @xe: the &xe_device
+ * @vfid: the VF identifier (can't be 0)
+ *
+ * This function is for PF only.
+ *
+ * Return: total migration data size in bytes or a negative error code on failure.
+ */
+ssize_t xe_sriov_pf_migration_size(struct xe_device *xe, unsigned int vfid)
+{
+	size_t size = 0;
+	struct xe_gt *gt;
+	ssize_t ret;
+	u8 gt_id;
+
+	xe_assert(xe, IS_SRIOV_PF(xe));
+	xe_assert(xe, vfid);
+
+	for_each_gt(gt, xe, gt_id) {
+		ret = xe_gt_sriov_pf_migration_size(gt, vfid);
+		if (ret < 0)
+			return ret;
+
+		size += ret;
+	}
+
+	return size;
+}

drivers/gpu/drm/xe/xe_sriov_pf_migration.h

@@ -18,6 +18,7 @@ int xe_sriov_pf_migration_restore_produce(struct xe_device *xe, unsigned int vfi
 					  struct xe_sriov_packet *data);
 struct xe_sriov_packet *
 xe_sriov_pf_migration_save_consume(struct xe_device *xe, unsigned int vfid);
+ssize_t xe_sriov_pf_migration_size(struct xe_device *xe, unsigned int vfid);
 wait_queue_head_t *xe_sriov_pf_migration_waitqueue(struct xe_device *xe, unsigned int vfid);
 
 ssize_t xe_sriov_pf_migration_read(struct xe_device *xe, unsigned int vfid,