drm/xe/oa: (De-)whitelist OA registers on OA stream open/release

Whitelist OA registers on stream open and de-whitelist on stream
close/release. Whitelisting is only done when 'stream->sample' is
true. 'stream->sample' is only true when (a) xe_observation_paranoid is set
to false by system admin, or (b) the process is perfmon_capable(). This
therefore enforces the OA register whitelisting security requirements.

Fixes: 828a8eaf37 ("drm/xe/oa: Add MMIO trigger support")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patch.msgid.link/20260615224227.34880-9-ashutosh.dixit@intel.com
(cherry picked from commit f8e6874f46)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

drivers/gpu/drm/xe/xe_oa.c

@@ -37,6 +37,7 @@
 #include "xe_oa.h"
 #include "xe_observation.h"
 #include "xe_pm.h"
+#include "xe_reg_whitelist.h"
 #include "xe_sched_job.h"
 #include "xe_sriov.h"
 #include "xe_sync.h"
@@ -885,6 +886,9 @@ static void xe_oa_stream_destroy(struct xe_oa_stream *stream)
 
 	mutex_destroy(&stream->stream_lock);
 
+	if (stream->sample)
+		xe_reg_dewhitelist_oa_regs(stream->gt);
+
 	xe_oa_disable_metric_set(stream);
 	xe_exec_queue_put(stream->k_exec_q);
 
@@ -1885,6 +1889,9 @@ static int xe_oa_stream_open_ioctl_locked(struct xe_oa *oa,
 		goto err_disable;
 	}
 
+	if (stream->sample)
+		xe_reg_whitelist_oa_regs(stream->gt);
+
 	/* Hold a reference on the drm device till stream_fd is released */
 	drm_dev_get(&stream->oa->xe->drm);