For some users of multi-lrc, e.g. split frame, it isn't safe to preempt mid BB. To safely enable preemption at the BB boundary, a handshake between to parent and child is needed. This is implemented via custom emit_bb_start & emit_fini_breadcrumb functions and enabled via by default if a context is configured by set parallel extension.
Signed-off-by: Matthew Brost matthew.brost@intel.com --- drivers/gpu/drm/i915/gt/intel_context.c | 2 +- drivers/gpu/drm/i915/gt/intel_context_types.h | 3 + drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h | 2 +- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 283 +++++++++++++++++- 4 files changed, 287 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index 5615be32879c..2de62649e275 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -561,7 +561,7 @@ void intel_context_bind_parent_child(struct intel_context *parent, GEM_BUG_ON(intel_context_is_child(child)); GEM_BUG_ON(intel_context_is_parent(child));
- parent->guc_number_children++; + child->guc_child_index = parent->guc_number_children++; list_add_tail(&child->guc_child_link, &parent->guc_child_list); child->parent = parent; diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h index 713d85b0b364..727f91e7f7c2 100644 --- a/drivers/gpu/drm/i915/gt/intel_context_types.h +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h @@ -246,6 +246,9 @@ struct intel_context { /** @guc_number_children: number of children if parent */ u8 guc_number_children;
+ /** @guc_child_index: index into guc_child_list if child */ + u8 guc_child_index; + /** * @parent_page: page in context used by parent for work queue, * work queue descriptor diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h index 6cd26dc060d1..9f61cfa5566a 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h @@ -188,7 +188,7 @@ struct guc_process_desc { u32 wq_status; u32 engine_presence; u32 priority; - u32 reserved[30]; + u32 reserved[36]; } __packed;
#define CONTEXT_REGISTRATION_FLAG_KMD BIT(0) diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 91330525330d..1a18f99bf12a 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -11,6 +11,7 @@ #include "gt/intel_context.h" #include "gt/intel_engine_pm.h" #include "gt/intel_engine_heartbeat.h" +#include "gt/intel_gpu_commands.h" #include "gt/intel_gt.h" #include "gt/intel_gt_irq.h" #include "gt/intel_gt_pm.h" @@ -366,10 +367,14 @@ static struct i915_priolist *to_priolist(struct rb_node *rb)
/* * When using multi-lrc submission an extra page in the context state is - * reserved for the process descriptor and work queue. + * reserved for the process descriptor, work queue, and preempt BB boundary + * handshake between the parent + childlren contexts. * * The layout of this page is below: * 0 guc_process_desc + * + sizeof(struct guc_process_desc) child go + * + CACHELINE_BYTES child join ... + * + CACHELINE_BYTES ... * ... unused * PAGE_SIZE / 2 work queue start * ... work queue @@ -1785,6 +1790,30 @@ static int deregister_context(struct intel_context *ce, u32 guc_id, bool loop) return __guc_action_deregister_context(guc, guc_id, loop); }
+static inline void clear_children_join_go_memory(struct intel_context *ce) +{ + u32 *mem = (u32 *)(__get_process_desc(ce) + 1); + u8 i; + + for (i = 0; i < ce->guc_number_children + 1; ++i) + mem[i * (CACHELINE_BYTES / sizeof(u32))] = 0; +} + +static inline u32 get_children_go_value(struct intel_context *ce) +{ + u32 *mem = (u32 *)(__get_process_desc(ce) + 1); + + return mem[0]; +} + +static inline u32 get_children_join_value(struct intel_context *ce, + u8 child_index) +{ + u32 *mem = (u32 *)(__get_process_desc(ce) + 1); + + return mem[(child_index + 1) * (CACHELINE_BYTES / sizeof(u32))]; +} + static void guc_context_policy_init(struct intel_engine_cs *engine, struct guc_lrc_desc *desc) { @@ -1867,6 +1896,8 @@ static int guc_lrc_desc_pin(struct intel_context *ce, bool loop) desc->context_flags = CONTEXT_REGISTRATION_FLAG_KMD; guc_context_policy_init(engine, desc); } + + clear_children_join_go_memory(ce); }
/* @@ -2943,6 +2974,31 @@ static const struct intel_context_ops virtual_child_context_ops = { .get_sibling = guc_virtual_get_sibling, };
+/* + * The below override of the breadcrumbs is enabled when the user configures a + * context for parallel submission (multi-lrc, parent-child). + * + * The overridden breadcrumbs implements an algorithm which allows the GuC to + * safely preempt all the hw contexts configured for parallel submission + * between each BB. The contract between the i915 and GuC is if the parent + * context can be preempted, all the children can be preempted, and the GuC will + * always try to preempt the parent before the children. A handshake between the + * parent / children breadcrumbs ensures the i915 holds up its end of the deal + * creating a window to preempt between each set of BBs. + */ +static int emit_bb_start_parent_no_preempt_mid_batch(struct i915_request *rq, + u64 offset, u32 len, + const unsigned int flags); +static int emit_bb_start_child_no_preempt_mid_batch(struct i915_request *rq, + u64 offset, u32 len, + const unsigned int flags); +static u32 * +emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs); +static u32 * +emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs); + static struct intel_context * guc_create_parallel(struct intel_engine_cs **engines, unsigned int num_siblings, @@ -2978,6 +3034,20 @@ guc_create_parallel(struct intel_engine_cs **engines, } }
+ parent->engine->emit_bb_start = + emit_bb_start_parent_no_preempt_mid_batch; + parent->engine->emit_fini_breadcrumb = + emit_fini_breadcrumb_parent_no_preempt_mid_batch; + parent->engine->emit_fini_breadcrumb_dw = + 12 + 4 * parent->guc_number_children; + for_each_child(parent, ce) { + ce->engine->emit_bb_start = + emit_bb_start_child_no_preempt_mid_batch; + ce->engine->emit_fini_breadcrumb = + emit_fini_breadcrumb_child_no_preempt_mid_batch; + ce->engine->emit_fini_breadcrumb_dw = 16; + } + kfree(siblings); return parent;
@@ -3362,6 +3432,204 @@ void intel_guc_submission_init_early(struct intel_guc *guc) guc->submission_selected = __guc_submission_selected(guc); }
+static inline u32 get_children_go_addr(struct intel_context *ce) +{ + GEM_BUG_ON(!intel_context_is_parent(ce)); + + return i915_ggtt_offset(ce->state) + + __get_process_desc_offset(ce) + + sizeof(struct guc_process_desc); +} + +static inline u32 get_children_join_addr(struct intel_context *ce, + u8 child_index) +{ + GEM_BUG_ON(!intel_context_is_parent(ce)); + + return get_children_go_addr(ce) + (child_index + 1) * CACHELINE_BYTES; +} + +#define PARENT_GO_BB 1 +#define PARENT_GO_FINI_BREADCRUMB 0 +#define CHILD_GO_BB 1 +#define CHILD_GO_FINI_BREADCRUMB 0 +static int emit_bb_start_parent_no_preempt_mid_batch(struct i915_request *rq, + u64 offset, u32 len, + const unsigned int flags) +{ + struct intel_context *ce = rq->context; + u32 *cs; + u8 i; + + GEM_BUG_ON(!intel_context_is_parent(ce)); + + cs = intel_ring_begin(rq, 10 + 4 * ce->guc_number_children); + if (IS_ERR(cs)) + return PTR_ERR(cs); + + /* Wait on chidlren */ + for (i = 0; i < ce->guc_number_children; ++i) { + *cs++ = (MI_SEMAPHORE_WAIT | + MI_SEMAPHORE_GLOBAL_GTT | + MI_SEMAPHORE_POLL | + MI_SEMAPHORE_SAD_EQ_SDD); + *cs++ = PARENT_GO_BB; + *cs++ = get_children_join_addr(ce, i); + *cs++ = 0; + } + + /* Turn off preemption */ + *cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE; + *cs++ = MI_NOOP; + + /* Tell children go */ + cs = gen8_emit_ggtt_write(cs, + CHILD_GO_BB, + get_children_go_addr(ce), + 0); + + /* Jump to batch */ + *cs++ = MI_BATCH_BUFFER_START_GEN8 | + (flags & I915_DISPATCH_SECURE ? 0 : BIT(8)); + *cs++ = lower_32_bits(offset); + *cs++ = upper_32_bits(offset); + *cs++ = MI_NOOP; + + intel_ring_advance(rq, cs); + + return 0; +} + +static int emit_bb_start_child_no_preempt_mid_batch(struct i915_request *rq, + u64 offset, u32 len, + const unsigned int flags) +{ + struct intel_context *ce = rq->context; + u32 *cs; + + GEM_BUG_ON(!intel_context_is_child(ce)); + + cs = intel_ring_begin(rq, 12); + if (IS_ERR(cs)) + return PTR_ERR(cs); + + /* Signal parent */ + cs = gen8_emit_ggtt_write(cs, + PARENT_GO_BB, + get_children_join_addr(ce->parent, + ce->guc_child_index), + 0); + + /* Wait parent on for go */ + *cs++ = (MI_SEMAPHORE_WAIT | + MI_SEMAPHORE_GLOBAL_GTT | + MI_SEMAPHORE_POLL | + MI_SEMAPHORE_SAD_EQ_SDD); + *cs++ = CHILD_GO_BB; + *cs++ = get_children_go_addr(ce->parent); + *cs++ = 0; + + /* Turn off preemption */ + *cs++ = MI_ARB_ON_OFF | MI_ARB_DISABLE; + + /* Jump to batch */ + *cs++ = MI_BATCH_BUFFER_START_GEN8 | + (flags & I915_DISPATCH_SECURE ? 0 : BIT(8)); + *cs++ = lower_32_bits(offset); + *cs++ = upper_32_bits(offset); + + intel_ring_advance(rq, cs); + + return 0; +} + +static u32 * +emit_fini_breadcrumb_parent_no_preempt_mid_batch(struct i915_request *rq, + u32 *cs) +{ + struct intel_context *ce = rq->context; + u8 i; + + GEM_BUG_ON(!intel_context_is_parent(ce)); + + /* Wait on children */ + for (i = 0; i < ce->guc_number_children; ++i) { + *cs++ = (MI_SEMAPHORE_WAIT | + MI_SEMAPHORE_GLOBAL_GTT | + MI_SEMAPHORE_POLL | + MI_SEMAPHORE_SAD_EQ_SDD); + *cs++ = PARENT_GO_FINI_BREADCRUMB; + *cs++ = get_children_join_addr(ce, i); + *cs++ = 0; + } + + /* Turn on preemption */ + *cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE; + *cs++ = MI_NOOP; + + /* Tell children go */ + cs = gen8_emit_ggtt_write(cs, + CHILD_GO_FINI_BREADCRUMB, + get_children_go_addr(ce), + 0); + + /* Emit fini breadcrumb */ + cs = gen8_emit_ggtt_write(cs, + rq->fence.seqno, + i915_request_active_timeline(rq)->hwsp_offset, + 0); + + /* User interrupt */ + *cs++ = MI_USER_INTERRUPT; + *cs++ = MI_NOOP; + + rq->tail = intel_ring_offset(rq, cs); + + return cs; +} + +static u32 * +emit_fini_breadcrumb_child_no_preempt_mid_batch(struct i915_request *rq, u32 *cs) +{ + struct intel_context *ce = rq->context; + + GEM_BUG_ON(!intel_context_is_child(ce)); + + /* Turn on preemption */ + *cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE; + *cs++ = MI_NOOP; + + /* Signal parent */ + cs = gen8_emit_ggtt_write(cs, + PARENT_GO_FINI_BREADCRUMB, + get_children_join_addr(ce->parent, + ce->guc_child_index), + 0); + + /* Wait parent on for go */ + *cs++ = (MI_SEMAPHORE_WAIT | + MI_SEMAPHORE_GLOBAL_GTT | + MI_SEMAPHORE_POLL | + MI_SEMAPHORE_SAD_EQ_SDD); + *cs++ = CHILD_GO_FINI_BREADCRUMB; + *cs++ = get_children_go_addr(ce->parent); + *cs++ = 0; + + /* Emit fini breadcrumb */ + cs = gen8_emit_ggtt_write(cs, + rq->fence.seqno, + i915_request_active_timeline(rq)->hwsp_offset, + 0); + + /* User interrupt */ + *cs++ = MI_USER_INTERRUPT; + *cs++ = MI_NOOP; + + rq->tail = intel_ring_offset(rq, cs); + + return cs; +} + static struct intel_context * g2h_context_lookup(struct intel_guc *guc, u32 desc_idx) { @@ -3807,6 +4075,19 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc, drm_printf(p, "\t\tWQI Status: %u\n\n", READ_ONCE(desc->wq_status));
+ drm_printf(p, "\t\tNumber Children: %u\n\n", + ce->guc_number_children); + if (ce->engine->emit_bb_start == + emit_bb_start_parent_no_preempt_mid_batch) { + u8 i; + + drm_printf(p, "\t\tChildren Go: %u\n\n", + get_children_go_value(ce)); + for (i = 0; i < ce->guc_number_children; ++i) + drm_printf(p, "\t\tChildren Join: %u\n", + get_children_join_value(ce, i)); + } + for_each_child(ce, child) guc_log_context(p, child); }