[PATCH v10 10/20] 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.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
---
 drivers/gpu/drm/xe/xe_vsec.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_vsec.c b/drivers/gpu/drm/xe/xe_vsec.c
index 26c58496fd93..ea60e2f3e917 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"
@@ -159,7 +161,12 @@ static int xe_guid_decode(u32 guid, int *index, u32 *offset)
  * @user_offset: a user offset relative to the beginning of the data to read
  * @count: bytes to read
  *
+ * This is a callback API.  I.e this can be accessed external to the XE driver
+ * (PMT driver scope).  Because of this, DRM hotplug needs to be verified
+ * (drm_dev_enter()).
+ *
  * Return:
+ * * -ENODEV device is not available (hotplug)
  * * -ENODATA for incorrect power state
  * * -EINVAL for unsupported PMT feature
  * * count   number of bytes read on success
@@ -172,13 +179,17 @@ 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;
 
 	xe_assert(xe, !IS_SRIOV_VF(xe));
 
+	if (!drm_dev_enter(&xe->drm, &idx))
+		return -ENODEV;
+
 	ret = xe_guid_decode(guid, &mem_region, &offset);
 	if (ret)
-		return ret;
+		goto dev_exit;
 
 	telem_addr += offset + user_offset;
 
@@ -188,11 +199,14 @@ 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;
 	}
 
 	scoped_guard(mutex, &xe->pmt.lock) {
@@ -204,7 +218,10 @@ 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