New subject: [Intel-gfx] [PATCH] drm/i915: avoid concurrent writes to aux_inv

28 Mar 2022

From: Fei Yang fei.yang@intel.com
GPU hangs have been observed when multiple engines write to the
same aux_inv register at the same time. To avoid this each engine
should only invalidate its own auxiliary table. The function
gen12_emit_flush_xcs() currently invalidate the auxiliary table for
all engines because the rq->engine is not necessarily the engine
eventually carrying out the request, and potentially the engine
could even be a virtual one (with engine->instance being -1).
With the MMIO remap feature, we can actually set bit 17 of MI_LRI
instruction and let the hardware to figure out the local aux_inv
register at runtime to avoid invalidating auxiliary table for all
engines.
Bspec: 45728
v2: Invalidate AUX table for indirect context as well.
Cc: Stuart Summers stuart.summers@intel.com
Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com
Signed-off-by: Chris Wilson chris.p.wilson@intel.com
Signed-off-by: Fei Yang fei.yang@intel.com
---
 drivers/gpu/drm/i915/gt/gen8_engine_cs.c     | 50 +++++---------------
 drivers/gpu/drm/i915/gt/gen8_engine_cs.h     |  4 +-
 drivers/gpu/drm/i915/gt/intel_gpu_commands.h |  1 +
 drivers/gpu/drm/i915/gt/intel_lrc.c          | 12 +++++
 4 files changed, 27 insertions(+), 40 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
index 36148887c699..047b5a710149 100644
--- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
@@ -6,7 +6,6 @@
 #include "gen8_engine_cs.h"
 #include "i915_drv.h"
 #include "intel_gpu_commands.h"
-#include "intel_gt_regs.h"
 #include "intel_lrc.h"
 #include "intel_ring.h"
@@ -165,33 +164,9 @@ static u32 preparser_disable(bool state)
    return MI_ARB_CHECK | 1 << 8 | state;
 }
-static i915_reg_t aux_inv_reg(const struct intel_engine_cs *engine)
+u32 *gen12_emit_aux_table_inv(u32 *cs, const i915_reg_t inv_reg)
 {
-	static const i915_reg_t vd[] = {
-		GEN12_VD0_AUX_NV,
-		GEN12_VD1_AUX_NV,
-		GEN12_VD2_AUX_NV,
-		GEN12_VD3_AUX_NV,
-	};
-
-	static const i915_reg_t ve[] = {
-		GEN12_VE0_AUX_NV,
-		GEN12_VE1_AUX_NV,
-	};
-
-	if (engine->class == VIDEO_DECODE_CLASS)
-		return vd[engine->instance];
-
-	if (engine->class == VIDEO_ENHANCEMENT_CLASS)
-		return ve[engine->instance];
-
-	GEM_BUG_ON("unknown aux_inv reg\n");
-	return INVALID_MMIO_REG;
-}
-
-static u32 *gen12_emit_aux_table_inv(const i915_reg_t inv_reg, u32 *cs)
-{
-	*cs++ = MI_LOAD_REGISTER_IMM(1);
+	*cs++ = MI_LOAD_REGISTER_IMM(1) | MI_LRI_MMIO_REMAP_EN;
    *cs++ = i915_mmio_reg_offset(inv_reg);
    *cs++ = AUX_INV;
    *cs++ = MI_NOOP;
@@ -274,7 +249,7 @@ int gen12_emit_flush_rcs(struct i915_request *rq, u32 mode)
if (!HAS_FLAT_CCS(rq->engine->i915)) {
    		/* hsdes: 1809175790 */
-			cs = gen12_emit_aux_table_inv(GEN12_GFX_CCS_AUX_NV, cs);
+			cs = gen12_emit_aux_table_inv(cs, GEN12_GFX_CCS_AUX_NV);
    	}
*cs++ = preparser_disable(false);
@@ -293,10 +268,12 @@ int gen12_emit_flush_xcs(struct i915_request *rq, u32 mode)
    if (mode & EMIT_INVALIDATE) {
    	cmd += 2;
-		if (!HAS_FLAT_CCS(rq->engine->i915)) {
+		if (!HAS_FLAT_CCS(rq->engine->i915) &&
+		    (rq->engine->class == VIDEO_DECODE_CLASS ||
+		     rq->engine->class == VIDEO_ENHANCEMENT_CLASS)) {
    		aux_inv = rq->engine->mask & ~BIT(BCS0);
    		if (aux_inv)
-				cmd += 2 * hweight32(aux_inv) + 2;
+				cmd += 4;
    	}
    }
@@ -329,15 +306,10 @@ int gen12_emit_flush_xcs(struct i915_request *rq, u32 mode)
    *cs++ = 0; /* value */
if (aux_inv) { /* hsdes: 1809175790 */
-		struct intel_engine_cs *engine;
-		unsigned int tmp;
-
-		*cs++ = MI_LOAD_REGISTER_IMM(hweight32(aux_inv));
-		for_each_engine_masked(engine, rq->engine->gt, aux_inv, tmp) {
-			*cs++ = i915_mmio_reg_offset(aux_inv_reg(engine));
-			*cs++ = AUX_INV;
-		}
-		*cs++ = MI_NOOP;
+		if (rq->engine->class == VIDEO_DECODE_CLASS)
+			cs = gen12_emit_aux_table_inv(cs, GEN12_VD0_AUX_NV);
+		else
+			cs = gen12_emit_aux_table_inv(cs, GEN12_VE0_AUX_NV);
    }
if (mode & EMIT_INVALIDATE)
diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.h b/drivers/gpu/drm/i915/gt/gen8_engine_cs.h
index cc6e21d3662a..107ab42539ab 100644
--- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.h
+++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.h
@@ -10,7 +10,7 @@
 #include <linux/types.h>
#include "i915_gem.h" /* GEM_BUG_ON */
-
+#include "intel_gt_regs.h"
 #include "intel_gpu_commands.h"
struct i915_request;
@@ -38,6 +38,8 @@ u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs);
 u32 *gen11_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs);
 u32 *gen12_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs);
+u32 *gen12_emit_aux_table_inv(u32 *cs, const i915_reg_t inv_reg);
+
 static inline u32 *
 __gen8_emit_pipe_control(u32 *batch, u32 flags0, u32 flags1, u32 offset)
 {
diff --git a/drivers/gpu/drm/i915/gt/intel_gpu_commands.h b/drivers/gpu/drm/i915/gt/intel_gpu_commands.h
index d112ffd56418..4243be030bc1 100644
--- a/drivers/gpu/drm/i915/gt/intel_gpu_commands.h
+++ b/drivers/gpu/drm/i915/gt/intel_gpu_commands.h
@@ -144,6 +144,7 @@
 #define MI_LOAD_REGISTER_IMM(x)	MI_INSTR(0x22, 2*(x)-1)
 /* Gen11+. addr = base + (ctx_restore ? offset & GENMASK(12,2) : offset) */
 #define   MI_LRI_LRM_CS_MMIO		REG_BIT(19)
+#define   MI_LRI_MMIO_REMAP_EN		REG_BIT(17)
 #define   MI_LRI_FORCE_POSTED		(1<<12)
 #define MI_LOAD_REGISTER_IMM_MAX_REGS (126)
 #define MI_STORE_REGISTER_MEM        MI_INSTR(0x24, 1)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 07bef7128fdb..dffef6ab4baf 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1208,6 +1208,10 @@ gen12_emit_indirect_ctx_rcs(const struct intel_context *ce, u32 *cs)
        IS_DG2_G11(ce->engine->i915))
    	cs = gen8_emit_pipe_control(cs, PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE, 0);
+	/* hsdes: 1809175790 */
+	if (!HAS_FLAT_CCS(ce->engine->i915))
+		cs = gen12_emit_aux_table_inv(cs, GEN12_GFX_CCS_AUX_NV);
+
    return cs;
 }
@@ -1225,6 +1229,14 @@ gen12_emit_indirect_ctx_xcs(const struct intel_context *ce, u32 *cs)
    					    PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE,
    					    0);
+	/* hsdes: 1809175790 */
+	if (!HAS_FLAT_CCS(ce->engine->i915)) {
+		if (ce->engine->class == VIDEO_DECODE_CLASS)
+			cs = gen12_emit_aux_table_inv(cs, GEN12_VD0_AUX_NV);
+		else if (ce->engine->class == VIDEO_ENHANCEMENT_CLASS)
+			cs = gen12_emit_aux_table_inv(cs, GEN12_VE0_AUX_NV);
+	}
+
    return cs;
 }
-- 
2.25.1


    