[Intel-gfx] [PATCH v3] drm/i915/lrc: Update PDPx registers with lri commands

[Michel Thierry]

A safer way to update the PDPx registers is sending lri commands, added
in the ring before the batchbuffer start. Otherwise, the ctx must be idle
before trying to change anything (but the ring-tail) in the ctx image. An
example where the ctx won't be idle is lite-restore.

This patch depends on 5b7e4c9ce ("drm/i915/gtt: Mark TLBS dirty for gen8+").

v2: Combine lri writes (and save 8 commands). (Mika)
v3: Rebase after ring/req changes, and removed references to deprecated patches.

Cc: Dave Gordon <david.s.gordon at intel.com>
Cc: Mika Kuoppala <mika.kuoppala at intel.com>
Signed-off-by: Michel Thierry <michel.thierry at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 42 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index d527b7b..e87d74c 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1379,6 +1379,34 @@ static int gen9_init_render_ring(struct intel_engine_cs *ring)
 	return init_workarounds_ring(ring);
 }
 
+static int intel_logical_ring_emit_pdps(struct drm_i915_gem_request *req)
+{
+	struct i915_hw_ppgtt *ppgtt = req->ctx->ppgtt;
+	struct intel_engine_cs *ring = req->ring;
+	struct intel_ringbuffer *ringbuf = req->ringbuf;
+	const int num_lri_cmds = GEN8_LEGACY_PDPES * 2;
+	int i, ret;
+
+	ret = intel_logical_ring_begin(req, num_lri_cmds * 2 + 2);
+	if (ret)
+		return ret;
+
+	intel_logical_ring_emit(ringbuf, MI_LOAD_REGISTER_IMM(num_lri_cmds));
+	for (i = GEN8_LEGACY_PDPES - 1; i >= 0; i--) {
+		const dma_addr_t pd_daddr = i915_page_dir_dma_addr(ppgtt, i);
+
+		intel_logical_ring_emit(ringbuf, GEN8_RING_PDP_UDW(ring, i));
+		intel_logical_ring_emit(ringbuf, upper_32_bits(pd_daddr));
+		intel_logical_ring_emit(ringbuf, GEN8_RING_PDP_LDW(ring, i));
+		intel_logical_ring_emit(ringbuf, lower_32_bits(pd_daddr));
+	}
+
+	intel_logical_ring_emit(ringbuf, MI_NOOP);
+	intel_logical_ring_advance(ringbuf);
+
+	return 0;
+}
+
 static int gen8_emit_bb_start(struct drm_i915_gem_request *req,
 			      u64 offset, unsigned dispatch_flags)
 {
@@ -1386,6 +1414,20 @@ static int gen8_emit_bb_start(struct drm_i915_gem_request *req,
 	bool ppgtt = !(dispatch_flags & I915_DISPATCH_SECURE);
 	int ret;
 
+	/* Don't rely in hw updating PDPs, specially in lite-restore.
+	 * Ideally, we should set Force PD Restore in ctx descriptor,
+	 * but we can't. Force Restore would be a second option, but
+	 * it is unsafe in case of lite-restore (because the ctx is
+	 * not idle). */
+	if (req->ctx->ppgtt &&
+	    (intel_ring_flag(req->ring) & req->ctx->ppgtt->pd_dirty_rings)) {
+		ret = intel_logical_ring_emit_pdps(req);
+		if (ret)
+			return ret;
+
+		req->ctx->ppgtt->pd_dirty_rings &= ~intel_ring_flag(req->ring);
+	}
+
 	ret = intel_logical_ring_begin(req, 4);
 	if (ret)
 		return ret;
-- 
2.4.5