[Intel-gfx] [PATCH 25/33] drm/i915/guc: Support request cancellation

Matthew Brost
2021-07-22T23:37:47Z

This adds GuC backend support for i915_request_cancel(), which in turn
makes CONFIG_DRM_I915_REQUEST_TIMEOUT work.

This implemenation makes use of fence while there is likely simplier
options. A fence was choosen because of another feature coming soon
which requires a user to block on a context until scheduling is
disabled. In that case we return the fence to the user and the user can
wait on that fence.

v2:
(Daniele)
- A comment about locking the blocked incr / decr
- A comments about the use of the fence
- Update commit message explaining why fence
- Delete redundant check blocked count in unblock function
- Ring buffer implementation
- Comment about blocked in submission path
- Shorter rpm path

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/gt/intel_context.c | 13 ++
drivers/gpu/drm/i915/gt/intel_context.h | 7 +
drivers/gpu/drm/i915/gt/intel_context_types.h | 7 +
.../drm/i915/gt/intel_execlists_submission.c | 18 ++
.../gpu/drm/i915/gt/intel_ring_submission.c | 16 ++
.../gpu/drm/i915/gt/uc/intel_guc_submission.c | 175 ++++++++++++++++++
drivers/gpu/drm/i915/i915_request.c | 14 +-
7 files changed, 237 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 237b70e98744..477c42d7d693 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -366,6 +366,12 @@ static int __intel_context_active(struct i915_active *active)
return 0;
}

+static int sw_fence_dummy_notify(struct i915_sw_fence *sf,
+ enum i915_sw_fence_notify state)
+{
+ return NOTIFY_DONE;
+}
+
void
intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
{
@@ -399,6 +405,13 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
ce->guc_id = GUC_INVALID_LRC_ID;
INIT_LIST_HEAD(&ce->guc_id_link);

+ /*
+ * Initialize fence to be complete as this is expected to be complete
+ * unless there is a pending schedule disable outstanding.
+ */
+ i915_sw_fence_init(&ce->guc_blocked, sw_fence_dummy_notify);
+ i915_sw_fence_commit(&ce->guc_blocked);
+
i915_active_init(&ce->active,
__intel_context_active, __intel_context_retire, 0);
}
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index 814d9277096a..876bdb08303c 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -70,6 +70,13 @@ intel_context_is_pinned(struct intel_context *ce)
return atomic_read(&ce->pin_count);
}

+static inline void intel_context_cancel_request(struct intel_context *ce,
+ struct i915_request *rq)
+{
+ GEM_BUG_ON(!ce->ops->cancel_request);
+ return ce->ops->cancel_request(ce, rq);
+}
+
/**
* intel_context_unlock_pinned - Releases the earlier locking of 'pinned' status
* @ce - the context
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 57c19ee3e313..005a64f2afa7 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -13,6 +13,7 @@
#include <linux/types.h>

#include "i915_active_types.h"
+#include "i915_sw_fence.h"
#include "i915_utils.h"
#include "intel_engine_types.h"
#include "intel_sseu.h"
@@ -42,6 +43,9 @@ struct intel_context_ops {
void (*unpin)(struct intel_context *ce);
void (*post_unpin)(struct intel_context *ce);

+ void (*cancel_request)(struct intel_context *ce,
+ struct i915_request *rq);
+
void (*enter)(struct intel_context *ce);
void (*exit)(struct intel_context *ce);

@@ -184,6 +188,9 @@ struct intel_context {
* GuC ID link - in list when unpinned but guc_id still valid in GuC
*/
struct list_head guc_id_link;
+
+ /* GuC context blocked fence */
+ struct i915_sw_fence guc_blocked;
};

#endif /* __INTEL_CONTEXT_TYPES__ */
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 60427b106bad..e7b42222b71d 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -114,6 +114,7 @@
#include "gen8_engine_cs.h"
#include "intel_breadcrumbs.h"
#include "intel_context.h"
+#include "intel_engine_heartbeat.h"
#include "intel_engine_pm.h"
#include "intel_engine_stats.h"
#include "intel_execlists_submission.h"
@@ -2587,11 +2588,26 @@ static int execlists_context_alloc(struct intel_context *ce)
return lrc_alloc(ce, ce->engine);
}

+static void execlists_context_cancel_request(struct intel_context *ce,
+ struct i915_request *rq)
+{
+ struct intel_engine_cs *engine = NULL;
+
+ i915_request_active_engine(rq, &engine);
+
+ if (engine && intel_engine_pulse(engine))
+ intel_gt_handle_error(engine->gt, engine->mask, 0,
+ "request cancellation by %s",
+ current->comm);
+}
+
static const struct intel_context_ops execlists_context_ops = {
.flags = COPS_HAS_INFLIGHT,

.alloc = execlists_context_alloc,

+ .cancel_request = execlists_context_cancel_request,
+
.pre_pin = execlists_context_pre_pin,
.pin = execlists_context_pin,
.unpin = lrc_unpin,
@@ -3604,6 +3620,8 @@ static const struct intel_context_ops virtual_context_ops = {

.alloc = virtual_context_alloc,

+ .cancel_request = execlists_context_cancel_request,
+
.pre_pin = virtual_context_pre_pin,
.pin = virtual_context_pin,
.unpin = lrc_unpin,
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 05bb9f449df1..2958e2fae380 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -16,6 +16,7 @@
#include "intel_reset.h"
#include "intel_ring.h"
#include "shmem_utils.h"
+#include "intel_engine_heartbeat.h"

/* Rough estimate of the typical request size, performing a flush,
* set-context and then emitting the batch.
@@ -604,9 +605,24 @@ static void ring_context_ban(struct intel_context *ce,
}
}

+static void ring_context_cancel_request(struct intel_context *ce,
+ struct i915_request *rq)
+{
+ struct intel_engine_cs *engine = NULL;
+
+ i915_request_active_engine(rq, &engine);
+
+ if (engine && intel_engine_pulse(engine))
+ intel_gt_handle_error(engine->gt, engine->mask, 0,
+ "request cancellation by %s",
+ current->comm);
+}
+
static const struct intel_context_ops ring_context_ops = {
.alloc = ring_context_alloc,

+ .cancel_request = ring_context_cancel_request,
+
.ban = ring_context_ban,

.pre_pin = ring_context_pre_pin,
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 3b9ba3bdd425..a26754b9b940 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -81,6 +81,11 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count);
*/
#define SCHED_STATE_NO_LOCK_ENABLED BIT(0)
#define SCHED_STATE_NO_LOCK_PENDING_ENABLE BIT(1)
+#define SCHED_STATE_NO_LOCK_BLOCKED_SHIFT 2
+#define SCHED_STATE_NO_LOCK_BLOCKED \
+ BIT(SCHED_STATE_NO_LOCK_BLOCKED_SHIFT)
+#define SCHED_STATE_NO_LOCK_BLOCKED_MASK \
+ (0xffff << SCHED_STATE_NO_LOCK_BLOCKED_SHIFT)
static inline bool context_enabled(struct intel_context *ce)
{
return (atomic_read(&ce->guc_sched_state_no_lock) &
@@ -116,6 +121,30 @@ static inline void clr_context_pending_enable(struct intel_context *ce)
&ce->guc_sched_state_no_lock);
}

+static inline u32 context_blocked(struct intel_context *ce)
+{
+ return (atomic_read(&ce->guc_sched_state_no_lock) &
+ SCHED_STATE_NO_LOCK_BLOCKED_MASK) >>
+ SCHED_STATE_NO_LOCK_BLOCKED_SHIFT;
+}
+
+static inline void incr_context_blocked(struct intel_context *ce)
+{
+ lockdep_assert_held(&ce->engine->sched_engine->lock);
+ atomic_add(SCHED_STATE_NO_LOCK_BLOCKED,
+ &ce->guc_sched_state_no_lock);
+ GEM_BUG_ON(!context_blocked(ce)); /* Overflow check */
+}
+
+static inline void decr_context_blocked(struct intel_context *ce)
+{
+ lockdep_assert_held(&ce->engine->sched_engine->lock);
+ GEM_BUG_ON(!context_blocked(ce));
+
+ atomic_sub(SCHED_STATE_NO_LOCK_BLOCKED,
+ &ce->guc_sched_state_no_lock);
+}
+
/*
* Below is a set of functions which control the GuC scheduling state which
* require a lock, aside from the special case where the functions are called
@@ -404,6 +433,14 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
if (unlikely(err))
goto out;
}
+
+ /*
+ * The request / context will be run on the hardware when scheduling
+ * gets enabled in the unblock.
+ */
+ if (unlikely(context_blocked(ce)))
+ goto out;
+
enabled = context_enabled(ce);

if (!enabled) {
@@ -532,6 +569,7 @@ static void __guc_context_destroy(struct intel_context *ce);
static void release_guc_id(struct intel_guc *guc, struct intel_context *ce);
static void guc_signal_context_fence(struct intel_context *ce);
static void guc_cancel_context_requests(struct intel_context *ce);
+static void guc_blocked_fence_complete(struct intel_context *ce);

static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
{
@@ -579,6 +617,10 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
}
intel_context_sched_disable_unpin(ce);
atomic_dec(&guc->outstanding_submission_g2h);
+ spin_lock_irqsave(&ce->guc_state.lock, flags);
+ guc_blocked_fence_complete(ce);
+ spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+
intel_context_put(ce);
}
}
@@ -1353,6 +1395,21 @@ static void guc_context_post_unpin(struct intel_context *ce)
lrc_post_unpin(ce);
}

+static void __guc_context_sched_enable(struct intel_guc *guc,
+ struct intel_context *ce)
+{
+ u32 action[] = {
+ INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET,
+ ce->guc_id,
+ GUC_CONTEXT_ENABLE
+ };
+
+ trace_intel_context_sched_enable(ce);
+
+ guc_submission_send_busy_loop(guc, action, ARRAY_SIZE(action),
+ G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
+}
+
static void __guc_context_sched_disable(struct intel_guc *guc,
struct intel_context *ce,
u16 guc_id)
@@ -1371,17 +1428,130 @@ static void __guc_context_sched_disable(struct intel_guc *guc,
G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true);
}

+static void guc_blocked_fence_complete(struct intel_context *ce)
+{
+ lockdep_assert_held(&ce->guc_state.lock);
+
+ if (!i915_sw_fence_done(&ce->guc_blocked))
+ i915_sw_fence_complete(&ce->guc_blocked);
+}
+
+static void guc_blocked_fence_reinit(struct intel_context *ce)
+{
+ lockdep_assert_held(&ce->guc_state.lock);
+ GEM_BUG_ON(!i915_sw_fence_done(&ce->guc_blocked));
+
+ /*
+ * This fence is always complete unless a pending schedule disable is
+ * outstanding. We arm the fence here and complete it when we receive
+ * the pending schedule disable complete message.
+ */
+ i915_sw_fence_fini(&ce->guc_blocked);
+ i915_sw_fence_reinit(&ce->guc_blocked);
+ i915_sw_fence_await(&ce->guc_blocked);
+ i915_sw_fence_commit(&ce->guc_blocked);
+}
+
static u16 prep_context_pending_disable(struct intel_context *ce)
{
lockdep_assert_held(&ce->guc_state.lock);

set_context_pending_disable(ce);
clr_context_enabled(ce);
+ guc_blocked_fence_reinit(ce);
intel_context_get(ce);

return ce->guc_id;
}

+static struct i915_sw_fence *guc_context_block(struct intel_context *ce)
+{
+ struct intel_guc *guc = ce_to_guc(ce);
+ struct i915_sched_engine *sched_engine = ce->engine->sched_engine;
+ unsigned long flags;
+ struct intel_runtime_pm *runtime_pm = ce->engine->uncore->rpm;
+ intel_wakeref_t wakeref;
+ u16 guc_id;
+ bool enabled;
+
+ /* Sync with submission path and unblock */
+ spin_lock_irqsave(&sched_engine->lock, flags);
+ incr_context_blocked(ce);
+ spin_unlock_irqrestore(&sched_engine->lock, flags);
+
+ spin_lock_irqsave(&ce->guc_state.lock, flags);
+ enabled = context_enabled(ce);
+ if (unlikely(!enabled || submission_disabled(guc))) {
+ if (enabled)
+ clr_context_enabled(ce);
+ spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+ return &ce->guc_blocked;
+ }
+
+ /*
+ * We add +2 here as the schedule disable complete CTB handler calls
+ * intel_context_sched_disable_unpin (-2 to pin_count).
+ */
+ atomic_add(2, &ce->pin_count);
+
+ guc_id = prep_context_pending_disable(ce);
+ spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+
+ with_intel_runtime_pm(runtime_pm, wakeref)
+ __guc_context_sched_disable(guc, ce, guc_id);
+
+ return &ce->guc_blocked;
+}
+
+static void guc_context_unblock(struct intel_context *ce)
+{
+ struct intel_guc *guc = ce_to_guc(ce);
+ struct i915_sched_engine *sched_engine = ce->engine->sched_engine;
+ unsigned long flags;
+ struct intel_runtime_pm *runtime_pm = ce->engine->uncore->rpm;
+ intel_wakeref_t wakeref;
+
+ GEM_BUG_ON(context_enabled(ce));
+
+ spin_lock_irqsave(&ce->guc_state.lock, flags);
+ if (unlikely(submission_disabled(guc) ||
+ !intel_context_is_pinned(ce) ||
+ context_pending_disable(ce) ||
+ context_blocked(ce) > 1)) {
+ spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+ goto out;
+ }
+
+ set_context_pending_enable(ce);
+ set_context_enabled(ce);
+ intel_context_get(ce);
+ spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+
+ with_intel_runtime_pm(runtime_pm, wakeref)
+ __guc_context_sched_enable(guc, ce);
+
+out:
+ spin_lock_irqsave(&sched_engine->lock, flags);
+ decr_context_blocked(ce);
+ spin_unlock_irqrestore(&sched_engine->lock, flags);
+}
+
+static void guc_context_cancel_request(struct intel_context *ce,
+ struct i915_request *rq)
+{
+ if (i915_sw_fence_signaled(&rq->submit)) {
+ struct i915_sw_fence *fence = guc_context_block(ce);
+
+ i915_sw_fence_wait(fence);
+ if (!i915_request_completed(rq)) {
+ __i915_request_skip(rq);
+ guc_reset_state(ce, intel_ring_wrap(ce->ring, rq->head),
+ true);
+ }
+ guc_context_unblock(ce);
+ }
+}
+
static void __guc_context_set_preemption_timeout(struct intel_guc *guc,
u16 guc_id,
u32 preemption_timeout)
@@ -1641,6 +1811,8 @@ static const struct intel_context_ops guc_context_ops = {

.ban = guc_context_ban,

+ .cancel_request = guc_context_cancel_request,
+
.enter = intel_context_enter_engine,
.exit = intel_context_exit_engine,

@@ -1836,6 +2008,8 @@ static const struct intel_context_ops virtual_guc_context_ops = {

.ban = guc_context_ban,

+ .cancel_request = guc_context_cancel_request,
+
.enter = guc_virtual_context_enter,
.exit = guc_virtual_context_exit,

@@ -2294,6 +2468,7 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc,
clr_context_banned(ce);
clr_context_pending_disable(ce);
__guc_signal_context_fence(ce);
+ guc_blocked_fence_complete(ce);
spin_unlock_irqrestore(&ce->guc_state.lock, flags);

if (banned) {
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 28f38b02a5d2..541a20371502 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -710,18 +710,6 @@ void i915_request_unsubmit(struct i915_request *request)
spin_unlock_irqrestore(&engine->sched_engine->lock, flags);
}

-static void __cancel_request(struct i915_request *rq)
-{
- struct intel_engine_cs *engine = NULL;
-
- i915_request_active_engine(rq, &engine);
-
- if (engine && intel_engine_pulse(engine))
- intel_gt_handle_error(engine->gt, engine->mask, 0,
- "request cancellation by %s",
- current->comm);
-}
-
void i915_request_cancel(struct i915_request *rq, int error)
{
if (!i915_request_set_error_once(rq, error))
@@ -729,7 +717,7 @@ void i915_request_cancel(struct i915_request *rq, int error)

set_bit(I915_FENCE_FLAG_SENTINEL, &rq->fence.flags);

- __cancel_request(rq);
+ intel_context_cancel_request(rq->context, rq);
}

static int __i915_sw_fence_call