drm/i915: Apply missed interrupt after reset w/a to all ringbuffer gen

Having completed a test run of gem_eio across all machines in CI we also
observe the phenomenon (of lost interrupts after resetting the GPU) on
gen3 machines as well as the previously sighted gen6/gen7. Let's apply
the same HWSTAM workaround that was effective for gen6+ for all, as
although we haven't seen the same failure on gen4/5 it seems prudent to
keep the code the same.

As a consequence we can remove the extra setting of HWSTAM and apply the
register from a single site.

v2: Delazy and move the HWSTAM into its own function
v3: Mask off all HWSP writes on driver unload and engine cleanup.
v4: And what about the physical hwsp?
v5: No, engine->init_hw() is not called from driver_init_hw(), don't be
daft. Really scrub HWSTAM as early as we can in driver_init_mmio()
v6: Rename set_hwsp as it was setting the mask not the hwsp register.
v7: Ville pointed out that although vcs(bsd) was introduced for g4x/ilk,
per-engine HWSTAM was not introduced until gen6!

References: https://bugs.freedesktop.org/show_bug.cgi?id=108735
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181218102712.11058-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_irq.c

@@ -3586,9 +3586,6 @@ static void ironlake_irq_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
-	if (IS_GEN(dev_priv, 5))
-		I915_WRITE(HWSTAM, 0xffffffff);
-
 	GEN3_IRQ_RESET(DE);
 	if (IS_GEN(dev_priv, 7))
 		I915_WRITE(GEN7_ERR_INT, 0xffffffff);
@@ -4368,8 +4365,6 @@ static void i8xx_irq_reset(struct drm_device *dev)
 
 	i9xx_pipestat_irq_reset(dev_priv);
 
-	I915_WRITE16(HWSTAM, 0xffff);
-
 	GEN2_IRQ_RESET();
 }
 
@@ -4537,8 +4532,6 @@ static void i915_irq_reset(struct drm_device *dev)
 
 	i9xx_pipestat_irq_reset(dev_priv);
 
-	I915_WRITE(HWSTAM, 0xffffffff);
-
 	GEN3_IRQ_RESET();
 }
 
@@ -4648,8 +4641,6 @@ static void i965_irq_reset(struct drm_device *dev)
 
 	i9xx_pipestat_irq_reset(dev_priv);
 
-	I915_WRITE(HWSTAM, 0xffffffff);
-
 	GEN3_IRQ_RESET();
 }
 

drivers/gpu/drm/i915/intel_engine_cs.c

@@ -261,6 +261,31 @@ static void __sprint_engine_name(char *name, const struct engine_info *info)
 			 info->instance) >= INTEL_ENGINE_CS_MAX_NAME);
 }
 
+void intel_engine_set_hwsp_writemask(struct intel_engine_cs *engine, u32 mask)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	i915_reg_t hwstam;
+
+	/*
+	 * Though they added more rings on g4x/ilk, they did not add
+	 * per-engine HWSTAM until gen6.
+	 */
+	if (INTEL_GEN(dev_priv) < 6 && engine->class != RENDER_CLASS)
+		return;
+
+	hwstam = RING_HWSTAM(engine->mmio_base);
+	if (INTEL_GEN(dev_priv) >= 3)
+		I915_WRITE(hwstam, mask);
+	else
+		I915_WRITE16(hwstam, mask);
+}
+
+static void intel_engine_sanitize_mmio(struct intel_engine_cs *engine)
+{
+	/* Mask off all writes into the unknown HWSP */
+	intel_engine_set_hwsp_writemask(engine, ~0u);
+}
+
 static int
 intel_engine_setup(struct drm_i915_private *dev_priv,
 		   enum intel_engine_id id)
@@ -312,6 +337,9 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
 
 	ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier);
 
+	/* Scrub mmio state on takeover */
+	intel_engine_sanitize_mmio(engine);
+
 	dev_priv->engine_class[info->class][info->instance] = engine;
 	dev_priv->engine[id] = engine;
 	return 0;
@@ -495,6 +523,9 @@ void intel_engine_setup_common(struct intel_engine_cs *engine)
 
 static void cleanup_status_page(struct intel_engine_cs *engine)
 {
+	/* Prevent writes into HWSP after returning the page to the system */
+	intel_engine_set_hwsp_writemask(engine, ~0u);
+
 	if (HWS_NEEDS_PHYSICAL(engine->i915)) {
 		void *addr = fetch_and_zero(&engine->status_page.page_addr);
 

drivers/gpu/drm/i915/intel_lrc.c

@@ -1655,7 +1655,7 @@ static void enable_execlists(struct intel_engine_cs *engine)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
 
-	I915_WRITE(RING_HWSTAM(engine->mmio_base), 0xffffffff);
+	intel_engine_set_hwsp_writemask(engine, ~0u); /* HWSTAM */
 
 	/*
 	 * Make sure we're not enabling the new 12-deep CSB

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -379,11 +379,25 @@ gen7_render_ring_flush(struct i915_request *rq, u32 mode)
 	return 0;
 }
 
-static void ring_setup_phys_status_page(struct intel_engine_cs *engine)
+static void set_hwstam(struct intel_engine_cs *engine, u32 mask)
+{
+	/*
+	 * Keep the render interrupt unmasked as this papers over
+	 * lost interrupts following a reset.
+	 */
+	if (engine->class == RENDER_CLASS) {
+		if (INTEL_GEN(engine->i915) >= 6)
+			mask &= ~BIT(0);
+		else
+			mask &= ~I915_USER_INTERRUPT;
+	}
+
+	intel_engine_set_hwsp_writemask(engine, mask);
+}
+
+static void set_hws_pga(struct intel_engine_cs *engine, phys_addr_t phys)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	struct page *page = virt_to_page(engine->status_page.page_addr);
-	phys_addr_t phys = PFN_PHYS(page_to_pfn(page));
 	u32 addr;
 
 	addr = lower_32_bits(phys);
@@ -393,12 +407,22 @@ static void ring_setup_phys_status_page(struct intel_engine_cs *engine)
 	I915_WRITE(HWS_PGA, addr);
 }
 
-static void intel_ring_setup_status_page(struct intel_engine_cs *engine)
+static void ring_setup_phys_status_page(struct intel_engine_cs *engine)
+{
+	struct page *page = virt_to_page(engine->status_page.page_addr);
+	phys_addr_t phys = PFN_PHYS(page_to_pfn(page));
+
+	set_hws_pga(engine, phys);
+	set_hwstam(engine, ~0u);
+}
+
+static void set_hwsp(struct intel_engine_cs *engine, u32 offset)
 {
 	struct drm_i915_private *dev_priv = engine->i915;
-	i915_reg_t mmio;
+	i915_reg_t hwsp;
 
-	/* The ring status page addresses are no longer next to the rest of
+	/*
+	 * The ring status page addresses are no longer next to the rest of
 	 * the ring registers as of gen7.
 	 */
 	if (IS_GEN(dev_priv, 7)) {
@@ -410,56 +434,55 @@ static void intel_ring_setup_status_page(struct intel_engine_cs *engine)
 		default:
 			GEM_BUG_ON(engine->id);
 		case RCS:
-			mmio = RENDER_HWS_PGA_GEN7;
+			hwsp = RENDER_HWS_PGA_GEN7;
 			break;
 		case BCS:
-			mmio = BLT_HWS_PGA_GEN7;
+			hwsp = BLT_HWS_PGA_GEN7;
 			break;
 		case VCS:
-			mmio = BSD_HWS_PGA_GEN7;
+			hwsp = BSD_HWS_PGA_GEN7;
 			break;
 		case VECS:
-			mmio = VEBOX_HWS_PGA_GEN7;
+			hwsp = VEBOX_HWS_PGA_GEN7;
 			break;
 		}
 	} else if (IS_GEN(dev_priv, 6)) {
-		mmio = RING_HWS_PGA_GEN6(engine->mmio_base);
+		hwsp = RING_HWS_PGA_GEN6(engine->mmio_base);
 	} else {
-		mmio = RING_HWS_PGA(engine->mmio_base);
+		hwsp = RING_HWS_PGA(engine->mmio_base);
 	}
 
-	if (INTEL_GEN(dev_priv) >= 6) {
+	I915_WRITE(hwsp, offset);
-		u32 mask = ~0u;
+	POSTING_READ(hwsp);
+}
 
-		/*
+static void flush_cs_tlb(struct intel_engine_cs *engine)
-		 * Keep the render interrupt unmasked as this papers over
+{
-		 * lost interrupts following a reset.
+	struct drm_i915_private *dev_priv = engine->i915;
-		 */
+	i915_reg_t instpm = RING_INSTPM(engine->mmio_base);
-		if (engine->id == RCS)
-			mask &= ~BIT(0);
 
-		I915_WRITE(RING_HWSTAM(engine->mmio_base), mask);
+	if (!IS_GEN_RANGE(dev_priv, 6, 7))
-	}
+		return;
 
-	I915_WRITE(mmio, engine->status_page.ggtt_offset);
+	/* ring should be idle before issuing a sync flush*/
-	POSTING_READ(mmio);
+	WARN_ON((I915_READ_MODE(engine) & MODE_IDLE) == 0);
 
-	/* Flush the TLB for this page */
+	I915_WRITE(instpm,
-	if (IS_GEN_RANGE(dev_priv, 6, 7)) {
+		   _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
-		i915_reg_t reg = RING_INSTPM(engine->mmio_base);
+				      INSTPM_SYNC_FLUSH));
+	if (intel_wait_for_register(dev_priv,
+				    instpm, INSTPM_SYNC_FLUSH, 0,
+				    1000))
+		DRM_ERROR("%s: wait for SyncFlush to complete for TLB invalidation timed out\n",
+			  engine->name);
+}
 
-		/* ring should be idle before issuing a sync flush*/
+static void ring_setup_status_page(struct intel_engine_cs *engine)
-		WARN_ON((I915_READ_MODE(engine) & MODE_IDLE) == 0);
+{
+	set_hwsp(engine, engine->status_page.ggtt_offset);
+	set_hwstam(engine, ~0u);
 
-		I915_WRITE(reg,
+	flush_cs_tlb(engine);
-			   _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
-					      INSTPM_SYNC_FLUSH));
-		if (intel_wait_for_register(dev_priv,
-					    reg, INSTPM_SYNC_FLUSH, 0,
-					    1000))
-			DRM_ERROR("%s: wait for SyncFlush to complete for TLB invalidation timed out\n",
-				  engine->name);
-	}
 }
 
 static bool stop_ring(struct intel_engine_cs *engine)
@@ -529,7 +552,7 @@ static int init_ring_common(struct intel_engine_cs *engine)
 	if (HWS_NEEDS_PHYSICAL(dev_priv))
 		ring_setup_phys_status_page(engine);
 	else
-		intel_ring_setup_status_page(engine);
+		ring_setup_status_page(engine);
 
 	intel_engine_reset_breadcrumbs(engine);
 

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -903,6 +903,8 @@ int intel_init_vebox_ring_buffer(struct intel_engine_cs *engine);
 int intel_engine_stop_cs(struct intel_engine_cs *engine);
 void intel_engine_cancel_stop_cs(struct intel_engine_cs *engine);
 
+void intel_engine_set_hwsp_writemask(struct intel_engine_cs *engine, u32 mask);
+
 u64 intel_engine_get_active_head(const struct intel_engine_cs *engine);
 u64 intel_engine_get_last_batch_head(const struct intel_engine_cs *engine);