[PATCH 2/4] drm/i915/guc: Cancel requests immediately

Matthew Brost
2022-01-24T15:08:00Z

Change the preemption timeout to the smallest possible value (1 us) when
disabling scheduling to cancel a request and restore it after
cancellation. This not only cancels the request as fast as possible, it
fixes a bug where the preemption timeout is 0 which results in the
schedule disable hanging forever.

Reported-by: Jani Saarinen <jani.saarinen@intel.com>
Fixes: 62eaf0ae217d4 ("drm/i915/guc: Support request cancellation")
Link: https://gitlab.freedesktop.org/drm/intel/-/issues/4960
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
drivers/gpu/drm/i915/gt/intel_context_types.h | 5 ++
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 46 +++++++++++--------
2 files changed, 31 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 30cd81ad8911a..730998823dbea 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -198,6 +198,11 @@ struct intel_context {
* each priority bucket
*/
u32 prio_count[GUC_CLIENT_PRIORITY_NUM];
+ /**
+ * @preemption_timeout: preemption timeout of the context, used
+ * to restore this value after request cancellation
+ */
+ u32 preemption_timeout;
} guc_state;

struct {
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 3918f1be114fa..966947c450253 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -2147,7 +2147,8 @@ static inline u32 get_children_join_value(struct intel_context *ce,
return __get_parent_scratch(ce)->join[child_index].semaphore;
}

-static void guc_context_policy_init(struct intel_engine_cs *engine,
+static void guc_context_policy_init(struct intel_context *ce,
+ struct intel_engine_cs *engine,
struct guc_lrc_desc *desc)
{
desc->policy_flags = 0;
@@ -2157,7 +2158,8 @@ static void guc_context_policy_init(struct intel_engine_cs *engine,

/* NB: For both of these, zero means disabled. */
desc->execution_quantum = engine->props.timeslice_duration_ms * 1000;
- desc->preemption_timeout = engine->props.preempt_timeout_ms * 1000;
+ ce->guc_state.preemption_timeout = engine->props.preempt_timeout_ms * 1000;
+ desc->preemption_timeout = ce->guc_state.preemption_timeout;
}

static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
@@ -2193,7 +2195,7 @@ static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
desc->hw_context_desc = ce->lrc.lrca;
desc->priority = ce->guc_state.prio;
desc->context_flags = CONTEXT_REGISTRATION_FLAG_KMD;
- guc_context_policy_init(engine, desc);
+ guc_context_policy_init(ce, engine, desc);

/*
* If context is a parent, we need to register a process descriptor
@@ -2226,7 +2228,7 @@ static int guc_lrc_desc_pin(struct intel_context *ce, bool loop)
desc->hw_context_desc = child->lrc.lrca;
desc->priority = ce->guc_state.prio;
desc->context_flags = CONTEXT_REGISTRATION_FLAG_KMD;
- guc_context_policy_init(engine, desc);
+ guc_context_policy_init(child, engine, desc);
}

clear_children_join_go_memory(ce);
@@ -2409,6 +2411,19 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
return ce->guc_id.id;
}

+static void __guc_context_set_preemption_timeout(struct intel_guc *guc,
+ u16 guc_id,
+ u32 preemption_timeout)
+{
+ u32 action[] = {
+ INTEL_GUC_ACTION_SET_CONTEXT_PREEMPTION_TIMEOUT,
+ guc_id,
+ preemption_timeout
+ };
+
+ intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
+}
+
static struct i915_sw_fence *guc_context_block(struct intel_context *ce)
{
struct intel_guc *guc = ce_to_guc(ce);
@@ -2442,8 +2457,10 @@ static struct i915_sw_fence *guc_context_block(struct intel_context *ce)

spin_unlock_irqrestore(&ce->guc_state.lock, flags);

- with_intel_runtime_pm(runtime_pm, wakeref)
+ with_intel_runtime_pm(runtime_pm, wakeref) {
+ __guc_context_set_preemption_timeout(guc, guc_id, 1);
__guc_context_sched_disable(guc, ce, guc_id);
+ }

return &ce->guc_state.blocked;
}
@@ -2492,8 +2509,10 @@ static void guc_context_unblock(struct intel_context *ce)

spin_unlock_irqrestore(&ce->guc_state.lock, flags);

- if (enable) {
- with_intel_runtime_pm(runtime_pm, wakeref)
+ with_intel_runtime_pm(runtime_pm, wakeref) {
+ __guc_context_set_preemption_timeout(guc, ce->guc_id.id,
+ ce->guc_state.preemption_timeout);
+ if (enable)
__guc_context_sched_enable(guc, ce);
}
}
@@ -2521,19 +2540,6 @@ static void guc_context_cancel_request(struct intel_context *ce,
}
}

-static void __guc_context_set_preemption_timeout(struct intel_guc *guc,
- u16 guc_id,
- u32 preemption_timeout)
-{
- u32 action[] = {
- INTEL_GUC_ACTION_SET_CONTEXT_PREEMPTION_TIMEOUT,
- guc_id,
- preemption_timeout
- };
-
- intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);
-}
-
static void guc_context_ban(struct intel_context *ce, struct i915_request *rq)
{
struct intel_guc *guc = ce_to_guc(ce);
--
2.34.1