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

On 28/03/2022 04:16, fei.yang@intel.com wrote:

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 | 48 ++++---------------- 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, 26 insertions(+), 39 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..8178be083b42 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(const i915_reg_t inv_reg, u32 *cs)

I think all helpers which emit to ring take cs as the first argument so it would be good to make this consistent.

{

• 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;

@@ -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(GEN12_VD0_AUX_NV, cs);
  

• else
  

• 	cs = gen12_emit_aux_table_inv(GEN12_VE0_AUX_NV, cs);
  

Not sure if, here and below, it would be worth to put register in a local and then have a single function call - up to you.

}

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..94f589e73d10 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(const i915_reg_t inv_reg, u32 *cs);

• 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..7581ef9e2cce 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(GEN12_GFX_CCS_AUX_NV, cs);
  

• 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(GEN12_VD0_AUX_NV, cs);
  

• else if (ce->engine->class == VIDEO_ENHANCEMENT_CLASS)
  

• 	cs = gen12_emit_aux_table_inv(GEN12_VE0_AUX_NV, cs);
  

• }
• return cs; }

Apart from the cs re-order looks good to me.

Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com

Regards,

Tvrtko