On 7/26/2021 5:23 PM, Matthew Brost wrote:
This adds GuC backend support for i915_request_cancel(), which in turn
makes CONFIG_DRM_I915_REQUEST_TIMEOUT work.

This implementation makes use of fence while there are likely simplier
options. A fence was chosen 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
v3:
  (Checkpatch)
   - Fix typos in commit message
  (Daniel)
   - Rework to simplier locking structure in guc_context_block / unblock

Signed-off-by: Matthew Brost <matthew.br...@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com>

Daniele

---
  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 |   9 +-
  .../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 | 188 ++++++++++++++++++
  drivers/gpu/drm/i915/i915_request.c           |  14 +-
  7 files changed, 251 insertions(+), 14 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..a5bc876face7 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);
@@ -156,7 +160,7 @@ struct intel_context {
                 * sched_state: scheduling state of this context using GuC
                 * submission
                 */
-               u8 sched_state;
+               u16 sched_state;
                /*
                 * fences: maintains of list of requests that have a submit
                 * fence related to GuC submission
@@ -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 b4a876736074..de5f9c86b9a4 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,
@@ -3608,6 +3624,8 @@ 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 ad9a38a861df..ee4f1f996efa 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -126,6 +126,9 @@ static inline void clr_context_pending_enable(struct 
intel_context *ce)
  #define SCHED_STATE_DESTROYED                         BIT(1)
  #define SCHED_STATE_PENDING_DISABLE                   BIT(2)
  #define SCHED_STATE_BANNED                            BIT(3)
+#define SCHED_STATE_BLOCKED_SHIFT                      4
+#define SCHED_STATE_BLOCKED            BIT(SCHED_STATE_BLOCKED_SHIFT)
+#define SCHED_STATE_BLOCKED_MASK       (0xfff << SCHED_STATE_BLOCKED_SHIFT)
  static inline void init_sched_state(struct intel_context *ce)
  {
        /* Only should be called from guc_lrc_desc_pin() */
@@ -203,6 +206,32 @@ static inline void clr_context_banned(struct intel_context 
*ce)
        ce->guc_state.sched_state &= ~SCHED_STATE_BANNED;
  }
+static inline u32 context_blocked(struct intel_context *ce)
+{
+       return (ce->guc_state.sched_state & SCHED_STATE_BLOCKED_MASK) >>
+               SCHED_STATE_BLOCKED_SHIFT;
+}
+
+static inline void incr_context_blocked(struct intel_context *ce)
+{
+       lockdep_assert_held(&ce->engine->sched_engine->lock);
+       lockdep_assert_held(&ce->guc_state.lock);
+
+       ce->guc_state.sched_state += SCHED_STATE_BLOCKED;
+
+       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);
+       lockdep_assert_held(&ce->guc_state.lock);
+
+       GEM_BUG_ON(!context_blocked(ce));       /* Underflow check */
+
+       ce->guc_state.sched_state -= SCHED_STATE_BLOCKED;
+}
+
  static inline bool context_guc_id_invalid(struct intel_context *ce)
  {
        return ce->guc_id == GUC_INVALID_LRC_ID;
@@ -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);
                }
        }
@@ -1354,6 +1396,21 @@ 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)
@@ -1372,17 +1429,143 @@ 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;
+
+       spin_lock_irqsave(&ce->guc_state.lock, flags);
+
+       /*
+        * Sync with submission path, increment before below changes to context
+        * state.
+        */
+       spin_lock(&sched_engine->lock);
+       incr_context_blocked(ce);
+       spin_unlock(&sched_engine->lock);
+
+       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;
+       bool enable;
+
+       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)) {
+               enable = false;
+       } else {
+               enable = true;
+               set_context_pending_enable(ce);
+               set_context_enabled(ce);
+               intel_context_get(ce);
+       }
+
+       /*
+        * Sync with submission path, decrement after above changes to context
+        * state.
+        */
+       spin_lock(&sched_engine->lock);
+       decr_context_blocked(ce);
+       spin_unlock(&sched_engine->lock);
+
+       spin_unlock_irqrestore(&ce->guc_state.lock, flags);
+
+       if (enable) {
+               with_intel_runtime_pm(runtime_pm, wakeref)
+                       __guc_context_sched_enable(guc, ce);
+       }
+}
+
+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)
@@ -1642,6 +1825,8 @@ 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,
@@ -1837,6 +2022,8 @@ 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,
@@ -2295,6 +2482,7 @@ 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

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