[Intel-gfx] [PATCH 04/13] drm/i915: Fail engine initialization if LRCA is incorrectly aligned

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

LRCA can change only when it goes from unpinned to pinned so it
makes sense to check its alignment at that point rather than at
every batch buffer submission.

Furthermore, if we check it at pin time we can actually
gracefuly fail the engine initialization rather than just
spamming the logs at runtime with WARNs.

v2: Return ENODEV for bad alignment. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 84977a6e6f3f..ff146a15d395 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -302,8 +302,6 @@ uint64_t intel_lr_context_descriptor(struct intel_context *ctx,
 	uint64_t lrca = i915_gem_obj_ggtt_offset(ctx_obj) +
 			LRC_PPHWSP_PN * PAGE_SIZE;
 
-	WARN_ON(lrca & 0xFFFFFFFF00000FFFULL);
-
 	desc |= lrca;
 	desc |= (u64)intel_execlists_ctx_id(ctx_obj) << GEN8_CTX_ID_SHIFT;
 
@@ -1030,6 +1028,7 @@ static int intel_lr_context_do_pin(struct intel_engine_cs *ring,
 {
 	struct drm_device *dev = ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	u64 lrca;
 	int ret = 0;
 
 	WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
@@ -1038,6 +1037,12 @@ static int intel_lr_context_do_pin(struct intel_engine_cs *ring,
 	if (ret)
 		return ret;
 
+	lrca = i915_gem_obj_ggtt_offset(ctx_obj) + LRC_PPHWSP_PN * PAGE_SIZE;
+	if (WARN_ON(lrca & 0xFFFFFFFF00000FFFULL)) {
+		ret = -ENODEV;
+		goto unpin_ctx_obj;
+	}
+
 	ret = intel_pin_and_map_ringbuffer_obj(ring->dev, ringbuf);
 	if (ret)
 		goto unpin_ctx_obj;
-- 
1.9.1