drm/i915/gtt: Downgrade Cherryview back to aliasing-ppgtt

With the upcoming change in timing (dramatically reducing the latency
between manipulating the ppGTT and execution), no amount of tweaking
could save Cherryview, it would always fail to invalidate its TLB.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190830180000.24608-2-chris@chris-wilson.co.uk

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

@@ -1871,60 +1871,6 @@ static int gen8_emit_init_breadcrumb(struct i915_request *rq)
 	return 0;
 }
 
-static int emit_pdps(struct i915_request *rq)
-{
-	const struct intel_engine_cs * const engine = rq->engine;
-	struct i915_ppgtt * const ppgtt = i915_vm_to_ppgtt(rq->hw_context->vm);
-	int err, i;
-	u32 *cs;
-
-	GEM_BUG_ON(intel_vgpu_active(rq->i915));
-
-	/*
-	 * Beware ye of the dragons, this sequence is magic!
-	 *
-	 * Small changes to this sequence can cause anything from
-	 * GPU hangs to forcewake errors and machine lockups!
-	 */
-
-	/* Flush any residual operations from the context load */
-	err = engine->emit_flush(rq, EMIT_FLUSH);
-	if (err)
-		return err;
-
-	/* Magic required to prevent forcewake errors! */
-	err = engine->emit_flush(rq, EMIT_INVALIDATE);
-	if (err)
-		return err;
-
-	cs = intel_ring_begin(rq, 4 * GEN8_3LVL_PDPES + 2);
-	if (IS_ERR(cs))
-		return PTR_ERR(cs);
-
-	/* Ensure the LRI have landed before we invalidate & continue */
-	*cs++ = MI_LOAD_REGISTER_IMM(2 * GEN8_3LVL_PDPES) | MI_LRI_FORCE_POSTED;
-	for (i = GEN8_3LVL_PDPES; i--; ) {
-		const dma_addr_t pd_daddr = i915_page_dir_dma_addr(ppgtt, i);
-		u32 base = engine->mmio_base;
-
-		*cs++ = i915_mmio_reg_offset(GEN8_RING_PDP_UDW(base, i));
-		*cs++ = upper_32_bits(pd_daddr);
-		*cs++ = i915_mmio_reg_offset(GEN8_RING_PDP_LDW(base, i));
-		*cs++ = lower_32_bits(pd_daddr);
-	}
-	*cs++ = MI_NOOP;
-
-	intel_ring_advance(rq, cs);
-
-	/* Be doubly sure the LRI have landed before proceeding */
-	err = engine->emit_flush(rq, EMIT_FLUSH);
-	if (err)
-		return err;
-
-	/* Re-invalidate the TLB for luck */
-	return engine->emit_flush(rq, EMIT_INVALIDATE);
-}
-
 static int execlists_request_alloc(struct i915_request *request)
 {
 	int ret;
@@ -1947,10 +1893,7 @@ static int execlists_request_alloc(struct i915_request *request)
 	 */
 
 	/* Unconditionally invalidate GPU caches and TLBs. */
-	if (i915_vm_is_4lvl(request->hw_context->vm))
-		ret = request->engine->emit_flush(request, EMIT_INVALIDATE);
-	else
-		ret = emit_pdps(request);
+	ret = request->engine->emit_flush(request, EMIT_INVALIDATE);
 	if (ret)
 		return ret;
 
@@ -3167,12 +3110,20 @@ static u32 intel_lr_indirect_ctx_offset(struct intel_engine_cs *engine)
 	return indirect_ctx_offset;
 }
 
+static struct i915_ppgtt *vm_alias(struct i915_address_space *vm)
+{
+	if (i915_is_ggtt(vm))
+		return i915_vm_to_ggtt(vm)->alias;
+	else
+		return i915_vm_to_ppgtt(vm);
+}
+
 static void execlists_init_reg_state(u32 *regs,
 				     struct intel_context *ce,
 				     struct intel_engine_cs *engine,
 				     struct intel_ring *ring)
 {
-	struct i915_ppgtt *ppgtt = i915_vm_to_ppgtt(ce->vm);
+	struct i915_ppgtt *ppgtt = vm_alias(ce->vm);
 	bool rcs = engine->class == RENDER_CLASS;
 	u32 base = engine->mmio_base;
 

drivers/gpu/drm/i915/i915_pci.c

@@ -570,7 +570,7 @@ static const struct intel_device_info intel_cherryview_info = {
 	.has_rps = true,
 	.has_logical_ring_contexts = 1,
 	.display.has_gmch = 1,
-	.ppgtt_type = INTEL_PPGTT_FULL,
+	.ppgtt_type = INTEL_PPGTT_ALIASING,
 	.ppgtt_size = 32,
 	.has_reset_engine = 1,
 	.has_snoop = true,