[PATCH v4 10/18] drm/xe/vsec: Support possible hotplug exit

["Michael J. Ruhl" <michael.j.ruhl@intel.com>]

DRM has an API that will verify that a device is valid in
the hotplug context.

Verify device is valid before access in the VSEC callback
API.

Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
---
 drivers/gpu/drm/xe/xe_vsec.c | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_vsec.c b/drivers/gpu/drm/xe/xe_vsec.c
index 468a221378fa..c6299629dc27 100644
--- a/drivers/gpu/drm/xe/xe_vsec.c
+++ b/drivers/gpu/drm/xe/xe_vsec.c
@@ -10,6 +10,8 @@
 #include <linux/pci.h>
 #include <linux/types.h>
 
+#include <drm/drm_drv.h>
+
 #include "xe_device.h"
 #include "xe_device_types.h"
 #include "xe_mmio.h"
@@ -140,6 +142,11 @@ static int xe_guid_decode(u32 guid, int *index, u32 *offset)
 	return 0;
 }
 
+/*
+ * xe_pmt_telem_read is a callback API.  I.e this can be accessed external to
+ * XE driver (PMT driver scope).  Because of this, DRM hotplug needs to be
+ * verified (drm_dev_enter()).
+ */
 int xe_pmt_telem_read(struct device *dev, u32 guid, u64 *data, loff_t user_offset,
 		      u32 count)
 {
@@ -148,14 +155,20 @@ int xe_pmt_telem_read(struct device *dev, u32 guid, u64 *data, loff_t user_offse
 	u32 cap_type = FIELD_GET(GUID_CAP_TYPE, guid);
 	u32 mem_region;
 	u32 offset;
-	int ret;
+	int ret = 0;
+	int idx;
 
-	if (IS_SRIOV_VF(xe))
-		return -EINVAL;
+	if (!drm_dev_enter(&xe->drm, &idx))
+		return -ENODEV;
+
+	if (IS_SRIOV_VF(xe)) {
+		ret = -EINVAL;
+		goto dev_exit;
+	}
 
 	ret = xe_guid_decode(guid, &mem_region, &offset);
 	if (ret)
-		return ret;
+		goto dev_exit;
 
 	telem_addr += offset + user_offset;
 
@@ -165,11 +178,14 @@ int xe_pmt_telem_read(struct device *dev, u32 guid, u64 *data, loff_t user_offse
 		xe_pm_runtime_get(xe);
 		break;
 	case TELEMETRY:
-		if (!xe_pm_runtime_get_if_active(xe))
-			return -ENODATA;
+		if (!xe_pm_runtime_get_if_active(xe)) {
+			ret = -ENODATA;
+			goto dev_exit;
+		}
 		break;
 	case WATCHER:
-		return -EINVAL;
+		ret = -EINVAL;
+		goto dev_exit;
 	}
 
 	mutex_lock(&xe->pmt.lock);
@@ -183,7 +199,10 @@ int xe_pmt_telem_read(struct device *dev, u32 guid, u64 *data, loff_t user_offse
 
 	xe_pm_runtime_put(xe);
 
-	return count;
+dev_exit:
+	drm_dev_exit(idx);
+
+	return ret == 0 ? count : ret;
 }
 
 static struct pmt_callbacks xe_pmt_cb = {
-- 
2.43.0