drm/i915/pvc: Define MOCS table for PVC

v2 (MattR):
 - Clarify comment above RING_CMD_CCTL programming.
 - Remove bspec reference from field definition.  (Lucas)
 - Add WARN if we try to use a (presumably uninitialized) wb_index of 0.
   On most platforms 0 is an invalid MOCS entry and even on the ones
   where it isn't, it isn't the right setting for wb_index.  (Lucas)

Bspec: 45101, 72161
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Ayaz A Siddiqui <ayaz.siddiqui@intel.com>
Signed-off-by: Fei Yang <fei.yang@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220505213812.3979301-4-matthew.d.roper@intel.com

drivers/gpu/drm/i915/gt/intel_gt_types.h

@@ -221,6 +221,7 @@ struct intel_gt {
 
 	struct {
 		u8 uc_index;
+		u8 wb_index; /* Only used on HAS_L3_CCS_READ() platforms */
 	} mocs;
 
 	struct intel_pxp pxp;

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

@@ -23,6 +23,7 @@ struct drm_i915_mocs_table {
 	unsigned int n_entries;
 	const struct drm_i915_mocs_entry *table;
 	u8 uc_index;
+	u8 wb_index; /* Only used on HAS_L3_CCS_READ() platforms */
 	u8 unused_entries_index;
 };
 
@@ -47,6 +48,7 @@ struct drm_i915_mocs_table {
 
 /* Helper defines */
 #define GEN9_NUM_MOCS_ENTRIES	64  /* 63-64 are reserved, but configured. */
+#define PVC_NUM_MOCS_ENTRIES	3
 
 /* (e)LLC caching options */
 /*
@@ -394,6 +396,17 @@ static const struct drm_i915_mocs_entry dg2_mocs_table_g10_ax[] = {
 	MOCS_ENTRY(3, 0, L3_3_WB | L3_LKUP(1)),
 };
 
+static const struct drm_i915_mocs_entry pvc_mocs_table[] = {
+	/* Error */
+	MOCS_ENTRY(0, 0, L3_3_WB),
+
+	/* UC */
+	MOCS_ENTRY(1, 0, L3_1_UC),
+
+	/* WB */
+	MOCS_ENTRY(2, 0, L3_3_WB),
+};
+
 enum {
 	HAS_GLOBAL_MOCS = BIT(0),
 	HAS_ENGINE_MOCS = BIT(1),
@@ -423,7 +436,14 @@ static unsigned int get_mocs_settings(const struct drm_i915_private *i915,
 	memset(table, 0, sizeof(struct drm_i915_mocs_table));
 
 	table->unused_entries_index = I915_MOCS_PTE;
-	if (IS_DG2(i915)) {
+	if (IS_PONTEVECCHIO(i915)) {
+		table->size = ARRAY_SIZE(pvc_mocs_table);
+		table->table = pvc_mocs_table;
+		table->n_entries = PVC_NUM_MOCS_ENTRIES;
+		table->uc_index = 1;
+		table->wb_index = 2;
+		table->unused_entries_index = 2;
+	} else if (IS_DG2(i915)) {
 		if (IS_DG2_GRAPHICS_STEP(i915, G10, STEP_A0, STEP_B0)) {
 			table->size = ARRAY_SIZE(dg2_mocs_table_g10_ax);
 			table->table = dg2_mocs_table_g10_ax;
@@ -622,6 +642,8 @@ void intel_set_mocs_index(struct intel_gt *gt)
 
 	get_mocs_settings(gt->i915, &table);
 	gt->mocs.uc_index = table.uc_index;
+	if (HAS_L3_CCS_READ(gt->i915))
+		gt->mocs.wb_index = table.wb_index;
 }
 
 void intel_mocs_init(struct intel_gt *gt)

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

@@ -1994,19 +1994,37 @@ void intel_engine_apply_whitelist(struct intel_engine_cs *engine)
 static void
 engine_fake_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
 {
-	u8 mocs;
+	u8 mocs_w, mocs_r;
 
 	/*
-	 * RING_CMD_CCTL are need to be programed to un-cached
-	 * for memory writes and reads outputted by Command
-	 * Streamers on Gen12 onward platforms.
+	 * RING_CMD_CCTL specifies the default MOCS entry that will be used
+	 * by the command streamer when executing commands that don't have
+	 * a way to explicitly specify a MOCS setting.  The default should
+	 * usually reference whichever MOCS entry corresponds to uncached
+	 * behavior, although use of a WB cached entry is recommended by the
+	 * spec in certain circumstances on specific platforms.
 	 */
 	if (GRAPHICS_VER(engine->i915) >= 12) {
-		mocs = engine->gt->mocs.uc_index;
+		mocs_r = engine->gt->mocs.uc_index;
+		mocs_w = engine->gt->mocs.uc_index;
+
+		if (HAS_L3_CCS_READ(engine->i915) &&
+		    engine->class == COMPUTE_CLASS) {
+			mocs_r = engine->gt->mocs.wb_index;
+
+			/*
+			 * Even on the few platforms where MOCS 0 is a
+			 * legitimate table entry, it's never the correct
+			 * setting to use here; we can assume the MOCS init
+			 * just forgot to initialize wb_index.
+			 */
+			drm_WARN_ON(&engine->i915->drm, mocs_r == 0);
+		}
+
 		wa_masked_field_set(wal,
 				    RING_CMD_CCTL(engine->mmio_base),
 				    CMD_CCTL_MOCS_MASK,
-				    CMD_CCTL_MOCS_OVERRIDE(mocs, mocs));
+				    CMD_CCTL_MOCS_OVERRIDE(mocs_w, mocs_r));
 	}
 }
 

drivers/gpu/drm/i915/i915_drv.h

@@ -1366,6 +1366,8 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
 
 #define HAS_LSPCON(dev_priv) (IS_DISPLAY_VER(dev_priv, 9, 10))
 
+#define HAS_L3_CCS_READ(i915) (INTEL_INFO(i915)->has_l3_ccs_read)
+
 /* DPF == dynamic parity feature */
 #define HAS_L3_DPF(dev_priv) (INTEL_INFO(dev_priv)->has_l3_dpf)
 #define NUM_L3_SLICES(dev_priv) (IS_HSW_GT3(dev_priv) ? \

drivers/gpu/drm/i915/i915_pci.c

@@ -1051,7 +1051,8 @@ static const struct intel_device_info ats_m_info = {
 
 #define XE_HPC_FEATURES \
 	XE_HP_FEATURES, \
-	.dma_mask_size = 52
+	.dma_mask_size = 52, \
+	.has_l3_ccs_read = 1
 
 __maybe_unused
 static const struct intel_device_info pvc_info = {

drivers/gpu/drm/i915/intel_device_info.h

@@ -143,6 +143,7 @@ enum intel_ppgtt_type {
 	func(has_heci_pxp); \
 	func(has_heci_gscfi); \
 	func(has_guc_deprivilege); \
+	func(has_l3_ccs_read); \
 	func(has_l3_dpf); \
 	func(has_llc); \
 	func(has_logical_ring_contexts); \