drm/xe: Add plumbing for indirect context workarounds

Some upcoming workarounds need to be emitted from the indirect workaround
context so lets add some plumbing where they will be able to easily slot
in.

No functional changes for now since everything is still deactivated.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Bspec: 45954
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250711160153.49833-7-tvrtko.ursulin@igalia.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Author: Tvrtko Ursulin

drivers/gpu/drm/xe/regs/xe_lrc_layout.h

@@ -12,6 +12,8 @@
 #define CTX_RING_START			(0x08 + 1)
 #define CTX_RING_CTL			(0x0a + 1)
 #define CTX_BB_PER_CTX_PTR		(0x12 + 1)
+#define CTX_CS_INDIRECT_CTX		(0x14 + 1)
+#define CTX_CS_INDIRECT_CTX_OFFSET	(0x16 + 1)
 #define CTX_TIMESTAMP			(0x22 + 1)
 #define CTX_TIMESTAMP_UDW		(0x24 + 1)
 #define CTX_INDIRECT_RING_STATE		(0x26 + 1)
@@ -36,4 +38,7 @@
 #define INDIRECT_CTX_RING_START_UDW	(0x08 + 1)
 #define INDIRECT_CTX_RING_CTL		(0x0a + 1)
 
+#define CTX_INDIRECT_CTX_OFFSET_MASK	REG_GENMASK(15, 6)
+#define CTX_INDIRECT_CTX_OFFSET_DEFAULT	REG_FIELD_PREP(CTX_INDIRECT_CTX_OFFSET_MASK, 0xd)
+
 #endif

drivers/gpu/drm/xe/xe_lrc.c

@@ -39,6 +39,7 @@
 #define LRC_ENGINE_INSTANCE			GENMASK_ULL(53, 48)
 
 #define LRC_PPHWSP_SIZE				SZ_4K
+#define LRC_INDIRECT_CTX_BO_SIZE		SZ_4K
 #define LRC_INDIRECT_RING_STATE_SIZE		SZ_4K
 #define LRC_WA_BB_SIZE				SZ_4K
 
@@ -48,6 +49,12 @@ lrc_to_xe(struct xe_lrc *lrc)
 	return gt_to_xe(lrc->fence_ctx.gt);
 }
 
+static bool
+gt_engine_needs_indirect_ctx(struct xe_gt *gt, enum xe_engine_class class)
+{
+	return false;
+}
+
 size_t xe_gt_lrc_size(struct xe_gt *gt, enum xe_engine_class class)
 {
 	struct xe_device *xe = gt_to_xe(gt);
@@ -717,7 +724,18 @@ static u32 __xe_lrc_ctx_timestamp_udw_offset(struct xe_lrc *lrc)
 
 static inline u32 __xe_lrc_indirect_ring_offset(struct xe_lrc *lrc)
 {
-	return xe_bo_size(lrc->bo) - LRC_WA_BB_SIZE - LRC_INDIRECT_RING_STATE_SIZE;
+	u32 offset = xe_bo_size(lrc->bo) - LRC_WA_BB_SIZE -
+		     LRC_INDIRECT_RING_STATE_SIZE;
+
+	if (lrc->flags & XE_LRC_FLAG_INDIRECT_CTX)
+		offset -= LRC_INDIRECT_CTX_BO_SIZE;
+
+	return offset;
+}
+
+static inline u32 __xe_lrc_indirect_ctx_offset(struct xe_lrc *lrc)
+{
+	return xe_bo_size(lrc->bo) - LRC_WA_BB_SIZE - LRC_INDIRECT_CTX_BO_SIZE;
 }
 
 static inline u32 __xe_lrc_wa_bb_offset(struct xe_lrc *lrc)
@@ -1077,6 +1095,58 @@ static int setup_wa_bb(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
 	return 0;
 }
 
+static int
+setup_indirect_ctx(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
+{
+	static struct bo_setup rcs_funcs[] = {
+	};
+	struct bo_setup_state state = {
+		.lrc = lrc,
+		.hwe = hwe,
+		.max_size = (63 * 64) /* max 63 cachelines */,
+		.offset = __xe_lrc_indirect_ctx_offset(lrc),
+	};
+	int ret;
+
+	if (!(lrc->flags & XE_LRC_FLAG_INDIRECT_CTX))
+		return 0;
+
+	if (hwe->class == XE_ENGINE_CLASS_RENDER ||
+	    hwe->class == XE_ENGINE_CLASS_COMPUTE) {
+		state.funcs = rcs_funcs;
+		state.num_funcs = ARRAY_SIZE(rcs_funcs);
+	}
+
+	if (xe_gt_WARN_ON(lrc->gt, !state.funcs))
+		return 0;
+
+	ret = setup_bo(&state);
+	if (ret)
+		return ret;
+
+	/*
+	 * Align to 64B cacheline so there's no garbage at the end for CS to
+	 * execute: size for indirect ctx must be a multiple of 64.
+	 */
+	while (state.written & 0xf) {
+		*state.ptr++ = MI_NOOP;
+		state.written++;
+	}
+
+	finish_bo(&state);
+
+	xe_lrc_write_ctx_reg(lrc,
+			     CTX_CS_INDIRECT_CTX,
+			     (xe_bo_ggtt_addr(lrc->bo) + state.offset) |
+			     /* Size in CLs. */
+			     (state.written * sizeof(u32) / 64));
+	xe_lrc_write_ctx_reg(lrc,
+			     CTX_CS_INDIRECT_CTX_OFFSET,
+			     CTX_INDIRECT_CTX_OFFSET_DEFAULT);
+
+	return 0;
+}
+
 #define PVC_CTX_ASID		(0x2e + 1)
 #define PVC_CTX_ACC_CTR_THOLD	(0x2a + 1)
 
@@ -1086,7 +1156,7 @@ static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
 {
 	struct xe_gt *gt = hwe->gt;
 	const u32 lrc_size = xe_gt_lrc_size(gt, hwe->class);
-	const u32 bo_size = ring_size + lrc_size + LRC_WA_BB_SIZE;
+	u32 bo_size = ring_size + lrc_size + LRC_WA_BB_SIZE;
 	struct xe_tile *tile = gt_to_tile(gt);
 	struct xe_device *xe = gt_to_xe(gt);
 	struct iosys_map map;
@@ -1101,6 +1171,12 @@ static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
 	lrc->flags = 0;
 	lrc->ring.size = ring_size;
 	lrc->ring.tail = 0;
+
+	if (gt_engine_needs_indirect_ctx(gt, hwe->class)) {
+		lrc->flags |= XE_LRC_FLAG_INDIRECT_CTX;
+		bo_size += LRC_INDIRECT_CTX_BO_SIZE;
+	}
+
 	if (xe_gt_has_indirect_ring_state(gt))
 		lrc->flags |= XE_LRC_FLAG_INDIRECT_RING_STATE;
 
@@ -1225,6 +1301,10 @@ static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
 	if (err)
 		goto err_lrc_finish;
 
+	err = setup_indirect_ctx(lrc, hwe);
+	if (err)
+		goto err_lrc_finish;
+
 	return 0;
 
 err_lrc_finish:

drivers/gpu/drm/xe/xe_lrc_types.h

@@ -29,7 +29,8 @@ struct xe_lrc {
 	struct xe_gt *gt;
 
 	/** @flags: LRC flags */
-#define XE_LRC_FLAG_INDIRECT_RING_STATE		0x1
+#define XE_LRC_FLAG_INDIRECT_CTX		0x1
+#define XE_LRC_FLAG_INDIRECT_RING_STATE		0x2
 	u32 flags;
 
 	/** @refcount: ref count of this lrc */