[PATCH v3] drm/xe/vsec: Allow for kernel context access

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

The PMT driver API allows kernel level access to device
data.  Because of this, the mutex lock use by the Xe copy
callback function turns out to be a poor choice.

Since the context of the caller can not be known, change
the mutex to a raw_spinlock to account for all use cases.

Fixes: 0c45e76fcc62 ("drm/xe/vsec: Support BMG devices")
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
---
v2: checkpatch fix, update email address
v3: use raw_spinlock

drivers/gpu/drm/xe/xe_device.c       | 5 ++---
 drivers/gpu/drm/xe/xe_device_types.h | 2 +-
 drivers/gpu/drm/xe/xe_vsec.c         | 4 ++--
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 399ae5f40321..0caa77d24f44 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -8,6 +8,7 @@
 #include <linux/aperture.h>
 #include <linux/delay.h>
 #include <linux/fault-inject.h>
+#include <linux/spinlock.h>
 #include <linux/units.h>
 
 #include <drm/drm_atomic_helper.h>
@@ -486,9 +487,7 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
 		goto err;
 	}
 
-	err = drmm_mutex_init(&xe->drm, &xe->pmt.lock);
-	if (err)
-		goto err;
+	raw_spin_lock_init(&xe->pmt.lock);
 
 	err = xe_display_create(xe);
 	if (WARN_ON(err))
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 06c65dace026..8f680a89ddb7 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -527,7 +527,7 @@ struct xe_device {
 	/** @pmt: Support the PMT driver callback interface */
 	struct {
 		/** @pmt.lock: protect access for telemetry data */
-		struct mutex lock;
+		raw_spinlock_t lock;
 	} pmt;
 
 	/**
diff --git a/drivers/gpu/drm/xe/xe_vsec.c b/drivers/gpu/drm/xe/xe_vsec.c
index b378848d3b7b..3941e1760ea3 100644
--- a/drivers/gpu/drm/xe/xe_vsec.c
+++ b/drivers/gpu/drm/xe/xe_vsec.c
@@ -6,7 +6,7 @@
 #include <linux/errno.h>
 #include <linux/intel_vsec.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
 #include <linux/pci.h>
 #include <linux/types.h>
 
@@ -164,7 +164,7 @@ static int xe_pmt_telem_read(struct pci_dev *pdev, u32 guid, u64 *data, loff_t u
 
 	telem_addr += offset + user_offset;
 
-	guard(mutex)(&xe->pmt.lock);
+	guard(raw_spinlock)(&xe->pmt.lock);
 
 	/* indicate that we are not at an appropriate power level */
 	if (!xe_pm_runtime_get_if_active(xe))
-- 
2.49.0