drm/i915: Fix __gen125_emit_bb_start() without WA

ce->wa_bb_page is allocated only for graphics version 12. However
__gen125_emit_bb_start() is used for any graphics version >= 12.50. For
the currently supported platforms this is not an issue, but for future
ones there's a mismatch causing the jump to
`wa_offset + DG2_PREDICATE_RESULT_BB` to be invalid since wa_offset is
not correct.

As in other places in the driver, check for graphics version "greater or
equal" to future-proof the support for new platforms.

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220930050903.3479619-2-lucas.demarchi@intel.com

drivers/gpu/drm/i915/gt/gen8_engine_cs.c

@@ -405,6 +405,8 @@ static int __gen125_emit_bb_start(struct i915_request *rq,
 	u32 wa_offset = lrc_indirect_bb(ce);
 	u32 *cs;
 
+	GEM_BUG_ON(!ce->wa_bb_page);
+
 	cs = intel_ring_begin(rq, 12);
 	if (IS_ERR(cs))
 		return PTR_ERR(cs);

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

@@ -825,19 +825,18 @@ static int lrc_ring_cmd_buf_cctl(const struct intel_engine_cs *engine)
 static u32
 lrc_ring_indirect_offset_default(const struct intel_engine_cs *engine)
 {
-	switch (GRAPHICS_VER(engine->i915)) {
-	default:
-		MISSING_CASE(GRAPHICS_VER(engine->i915));
-		fallthrough;
-	case 12:
+	if (GRAPHICS_VER(engine->i915) >= 12)
 		return GEN12_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT;
-	case 11:
+	else if (GRAPHICS_VER(engine->i915) >= 11)
 		return GEN11_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT;
-	case 9:
+	else if (GRAPHICS_VER(engine->i915) >= 9)
 		return GEN9_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT;
-	case 8:
+	else if (GRAPHICS_VER(engine->i915) >= 8)
 		return GEN8_CTX_RCS_INDIRECT_CTX_OFFSET_DEFAULT;
-	}
+
+	GEM_BUG_ON(GRAPHICS_VER(engine->i915) < 8);
+
+	return 0;
 }
 
 static void
@@ -1092,7 +1091,7 @@ __lrc_alloc_state(struct intel_context *ce, struct intel_engine_cs *engine)
 	if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
 		context_size += I915_GTT_PAGE_SIZE; /* for redzone */
 
-	if (GRAPHICS_VER(engine->i915) == 12) {
+	if (GRAPHICS_VER(engine->i915) >= 12) {
 		ce->wa_bb_page = context_size / PAGE_SIZE;
 		context_size += PAGE_SIZE;
 	}