drm/i915/gt: Drop invalidate_csb_entries

Drop invalidate_csb_entries and directly call drm_clflush_virt_range.
This allows for one less function call, and prevent complier errors when
building for non-x86 architectures.

v2(Michael Cheng): Drop invalidate_csb_entries function and directly
		   invoke drm_clflush_virt_range. Thanks to Tvrtko for the
		   sugguestion.

v3(Michael Cheng): Use correct parameters for drm_clflush_virt_range.
		   Thanks to Tvrtko for pointing this out.

v4(Michael Cheng): Simplify &execlists->csb_status[0] to
		   execlists->csb_status. Thanks to Matt Roper for the
		   suggestion.
Signed-off-by: Michael Cheng <michael.cheng@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220321223819.72833-3-michael.cheng@intel.com

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

@@ -1650,12 +1650,6 @@ cancel_port_requests(struct intel_engine_execlists * const execlists,
 	return inactive;
 }
 
-static void invalidate_csb_entries(const u64 *first, const u64 *last)
-{
-	clflush((void *)first);
-	clflush((void *)last);
-}
-
 /*
  * Starting with Gen12, the status has a new format:
  *
@@ -2003,7 +1997,7 @@ process_csb(struct intel_engine_cs *engine, struct i915_request **inactive)
 	 * the wash as hardware, working or not, will need to do the
 	 * invalidation before.
 	 */
-	invalidate_csb_entries(&buf[0], &buf[num_entries - 1]);
+	drm_clflush_virt_range(&buf[0], num_entries * sizeof(buf[0]));
 
 	/*
 	 * We assume that any event reflects a change in context flow
@@ -2787,8 +2781,9 @@ static void reset_csb_pointers(struct intel_engine_cs *engine)
 
 	/* Check that the GPU does indeed update the CSB entries! */
 	memset(execlists->csb_status, -1, (reset_value + 1) * sizeof(u64));
-	invalidate_csb_entries(&execlists->csb_status[0],
-			       &execlists->csb_status[reset_value]);
+	drm_clflush_virt_range(execlists->csb_status,
+			       execlists->csb_size *
+			       sizeof(execlists->csb_status));
 
 	/* Once more for luck and our trusty paranoia */
 	ENGINE_WRITE(engine, RING_CONTEXT_STATUS_PTR,