On Wed, 30 Nov 2022 17:05:32 -0800, Umesh Nerlige Ramappa wrote: > > On MTL, gt->scratch was using stolen lmem. An MI_SRM to stolen lmem > caused a hang that was attributed to saving and restoring the GPR > registers used for noa_wait. > > Add an additional page in noa_wait BO to save/restore GPR registers for > the noa_wait logic.
Mostly copying R-b's from https://patchwork.freedesktop.org/series/111411/ here. Reviewed-by: Ashutosh Dixit <ashutosh.di...@intel.com> > > Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.rama...@intel.com> > --- > drivers/gpu/drm/i915/gt/intel_gt_types.h | 6 ------ > drivers/gpu/drm/i915/i915_perf.c | 25 ++++++++++++++++-------- > 2 files changed, 17 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h > b/drivers/gpu/drm/i915/gt/intel_gt_types.h > index c1d9cd255e06..13dffe0a3d20 100644 > --- a/drivers/gpu/drm/i915/gt/intel_gt_types.h > +++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h > @@ -296,12 +296,6 @@ enum intel_gt_scratch_field { > > /* 8 bytes */ > INTEL_GT_SCRATCH_FIELD_COHERENTL3_WA = 256, > - > - /* 6 * 8 bytes */ > - INTEL_GT_SCRATCH_FIELD_PERF_CS_GPR = 2048, > - > - /* 4 bytes */ > - INTEL_GT_SCRATCH_FIELD_PERF_PREDICATE_RESULT_1 = 2096, > }; > > #endif /* __INTEL_GT_TYPES_H__ */ > diff --git a/drivers/gpu/drm/i915/i915_perf.c > b/drivers/gpu/drm/i915/i915_perf.c > index 00e09bb18b13..7790a88f10d8 100644 > --- a/drivers/gpu/drm/i915/i915_perf.c > +++ b/drivers/gpu/drm/i915/i915_perf.c > @@ -1842,8 +1842,7 @@ static u32 *save_restore_register(struct > i915_perf_stream *stream, u32 *cs, > for (d = 0; d < dword_count; d++) { > *cs++ = cmd; > *cs++ = i915_mmio_reg_offset(reg) + 4 * d; > - *cs++ = intel_gt_scratch_offset(stream->engine->gt, > - offset) + 4 * d; > + *cs++ = i915_ggtt_offset(stream->noa_wait) + offset + 4 * d; > *cs++ = 0; > } > > @@ -1876,7 +1875,13 @@ static int alloc_noa_wait(struct i915_perf_stream > *stream) > MI_PREDICATE_RESULT_2_ENGINE(base) : > > MI_PREDICATE_RESULT_1(RENDER_RING_BASE); > > - bo = i915_gem_object_create_internal(i915, 4096); > + /* > + * gt->scratch was being used to save/restore the GPR registers, but on > + * MTL the scratch uses stolen lmem. An MI_SRM to this memory region > + * causes an engine hang. Instead allocate an additional page here to > + * save/restore GPR registers > + */ > + bo = i915_gem_object_create_internal(i915, 8192); > if (IS_ERR(bo)) { > drm_err(&i915->drm, > "Failed to allocate NOA wait batchbuffer\n"); > @@ -1910,14 +1915,19 @@ static int alloc_noa_wait(struct i915_perf_stream > *stream) > goto err_unpin; > } > > + stream->noa_wait = vma; > + > +#define GPR_SAVE_OFFSET 4096 > +#define PREDICATE_SAVE_OFFSET 4160 > + > /* Save registers. */ > for (i = 0; i < N_CS_GPR; i++) > cs = save_restore_register( > stream, cs, true /* save */, CS_GPR(i), > - INTEL_GT_SCRATCH_FIELD_PERF_CS_GPR + 8 * i, 2); > + GPR_SAVE_OFFSET + 8 * i, 2); > cs = save_restore_register( > stream, cs, true /* save */, mi_predicate_result, > - INTEL_GT_SCRATCH_FIELD_PERF_PREDICATE_RESULT_1, 1); > + PREDICATE_SAVE_OFFSET, 1); > > /* First timestamp snapshot location. */ > ts0 = cs; > @@ -2033,10 +2043,10 @@ static int alloc_noa_wait(struct i915_perf_stream > *stream) > for (i = 0; i < N_CS_GPR; i++) > cs = save_restore_register( > stream, cs, false /* restore */, CS_GPR(i), > - INTEL_GT_SCRATCH_FIELD_PERF_CS_GPR + 8 * i, 2); > + GPR_SAVE_OFFSET + 8 * i, 2); > cs = save_restore_register( > stream, cs, false /* restore */, mi_predicate_result, > - INTEL_GT_SCRATCH_FIELD_PERF_PREDICATE_RESULT_1, 1); > + PREDICATE_SAVE_OFFSET, 1); > > /* And return to the ring. */ > *cs++ = MI_BATCH_BUFFER_END; > @@ -2046,7 +2056,6 @@ static int alloc_noa_wait(struct i915_perf_stream > *stream) > i915_gem_object_flush_map(bo); > __i915_gem_object_release_map(bo); > > - stream->noa_wait = vma; > goto out_ww; > > err_unpin: > -- > 2.36.1 >
