Re: [Intel-gfx] [RFC PATCH 55/97] drm/i915/guc: Update intel_gt_wait_for_idle to work with GuC

On 06/05/2021 20:14, Matthew Brost wrote:

When running the GuC the GPU can't be considered idle if the GuC still has contexts pinned. As such, a call has been added in intel_gt_wait_for_idle to idle the UC and in turn the GuC by waiting for the number of unpinned contexts to go to zero.

Cc: John Harrison john.c.harrison@intel.com Signed-off-by: Matthew Brost matthew.brost@intel.com

---

drivers/gpu/drm/i915/gem/i915_gem_mman.c | 3 +- drivers/gpu/drm/i915/gt/intel_gt.c | 18 ++++ drivers/gpu/drm/i915/gt/intel_gt.h | 2 + drivers/gpu/drm/i915/gt/intel_gt_requests.c | 22 ++--- drivers/gpu/drm/i915/gt/intel_gt_requests.h | 7 +- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 4 + drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 1 + drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h | 4 + .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 91 ++++++++++++++++++- drivers/gpu/drm/i915/gt/uc/intel_uc.h | 5 + drivers/gpu/drm/i915/i915_debugfs.c | 1 + drivers/gpu/drm/i915/i915_gem_evict.c | 1 + .../gpu/drm/i915/selftests/igt_live_test.c | 2 +- .../gpu/drm/i915/selftests/mock_gem_device.c | 3 +- 14 files changed, 137 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 8598a1c78a4c..2f5295c9408d 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -634,7 +634,8 @@ mmap_offset_attach(struct drm_i915_gem_object *obj, goto insert;

/* Attempt to reap some mmap space from dead objects */

• err = intel_gt_retire_requests_timeout(&i915->gt, MAX_SCHEDULE_TIMEOUT);

• err = intel_gt_retire_requests_timeout(&i915->gt, MAX_SCHEDULE_TIMEOUT,

• 			       NULL);
  

  if (err) goto err;

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c index 8d77dcbad059..1742a8561f69 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt.c +++ b/drivers/gpu/drm/i915/gt/intel_gt.c @@ -574,6 +574,24 @@ static void __intel_gt_disable(struct intel_gt *gt) GEM_BUG_ON(intel_gt_pm_is_awake(gt)); }

+int intel_gt_wait_for_idle(struct intel_gt *gt, long timeout) +{

• long rtimeout;
• /* If the device is asleep, we have no requests outstanding */
• if (!intel_gt_pm_is_awake(gt))

• return 0;
  

• while ((timeout = intel_gt_retire_requests_timeout(gt, timeout,

• 					   &rtimeout)) > 0) {
  

• cond_resched();
  

• if (signal_pending(current))
  

• 	return -EINTR;
  

• }
• return timeout ? timeout : intel_uc_wait_for_idle(&gt->uc, rtimeout);

+}

• int intel_gt_init(struct intel_gt *gt) { int err;

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.h b/drivers/gpu/drm/i915/gt/intel_gt.h index 7ec395cace69..c775043334bf 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt.h +++ b/drivers/gpu/drm/i915/gt/intel_gt.h @@ -48,6 +48,8 @@ void intel_gt_driver_release(struct intel_gt *gt);

void intel_gt_driver_late_release(struct intel_gt *gt);

+int intel_gt_wait_for_idle(struct intel_gt *gt, long timeout);

• void intel_gt_check_and_clear_faults(struct intel_gt *gt); void intel_gt_clear_error_registers(struct intel_gt *gt, intel_engine_mask_t engine_mask);

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c index 647eca9d867a..c6c702f236fa 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c @@ -13,6 +13,7 @@ #include "intel_gt_pm.h" #include "intel_gt_requests.h" #include "intel_timeline.h" +#include "uc/intel_uc.h"

static bool retire_requests(struct intel_timeline *tl) { @@ -130,7 +131,8 @@ void intel_engine_fini_retire(struct intel_engine_cs *engine) GEM_BUG_ON(engine->retire); }

-long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout) +long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout,

• 		      long *rtimeout)
  

What is 'rtimeout', I know remaining, but it can be more self-descriptive to start with.

It feels a bit churny for what it is. How plausible would be alternatives to either change existing timeout to in/out, or measure sleep internally in this function, or just risk sleeping twice as long by passing the original timeout to uc idle as well?

{ struct intel_gt_timelines *timelines = &gt->timelines; struct intel_timeline *tl, *tn; @@ -195,22 +197,10 @@ out_active: spin_lock(&timelines->lock); if (flush_submission(gt, timeout)) /* Wait, there's more! */ active_count++;

• return active_count ? timeout : 0;

-}

-int intel_gt_wait_for_idle(struct intel_gt *gt, long timeout) -{

• /* If the device is asleep, we have no requests outstanding */
• if (!intel_gt_pm_is_awake(gt))

• return 0;
  

• while ((timeout = intel_gt_retire_requests_timeout(gt, timeout)) > 0) {

• cond_resched();
  

• if (signal_pending(current))
  

• 	return -EINTR;
  

• }

• if (rtimeout)

• *rtimeout = timeout;
  
  

• return timeout;

• return active_count ? timeout : 0; }

  static void retire_work_handler(struct work_struct *work)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.h b/drivers/gpu/drm/i915/gt/intel_gt_requests.h index fcc30a6e4fe9..4419787124e2 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.h +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.h @@ -10,10 +10,11 @@ struct intel_engine_cs; struct intel_gt; struct intel_timeline;

-long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout); +long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout,

• 		      long *rtimeout);
  

  static inline void intel_gt_retire_requests(struct intel_gt *gt) {

• intel_gt_retire_requests_timeout(gt, 0);

• intel_gt_retire_requests_timeout(gt, 0, NULL); }

  void intel_engine_init_retire(struct intel_engine_cs *engine);

@@ -21,8 +22,6 @@ void intel_engine_add_retire(struct intel_engine_cs *engine, struct intel_timeline *tl); void intel_engine_fini_retire(struct intel_engine_cs *engine);

-int intel_gt_wait_for_idle(struct intel_gt *gt, long timeout);

• void intel_gt_init_requests(struct intel_gt *gt); void intel_gt_park_requests(struct intel_gt *gt); void intel_gt_unpark_requests(struct intel_gt *gt);

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 485e98f3f304..47eaa69809e8 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -38,6 +38,8 @@ struct intel_guc { spinlock_t irq_lock; unsigned int msg_enabled_mask;

• atomic_t outstanding_submission_g2h;
• struct { bool enabled; void (*reset)(struct intel_guc *guc);

@@ -239,6 +241,8 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask) spin_unlock_irq(&guc->irq_lock); }

+int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout);

• int intel_guc_reset_engine(struct intel_guc *guc, struct intel_engine_cs *engine);

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c index f1893030ca88..cf701056fa14 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c @@ -111,6 +111,7 @@ void intel_guc_ct_init_early(struct intel_guc_ct *ct) INIT_LIST_HEAD(&ct->requests.incoming); INIT_WORK(&ct->requests.worker, ct_incoming_request_worker_func); tasklet_init(&ct->receive_tasklet, ct_receive_tasklet_func, (unsigned long)ct);

• init_waitqueue_head(&ct->wq); }

  static inline const char *guc_ct_buffer_type_to_str(u32 type)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h index 660bf37238e2..ab1b79ab960b 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.h @@ -10,6 +10,7 @@ #include <linux/spinlock.h> #include <linux/workqueue.h> #include <linux/ktime.h> +#include <linux/wait.h>

#include "intel_guc_fwif.h"

@@ -68,6 +69,9 @@ struct intel_guc_ct {

struct tasklet_struct receive_tasklet;

• /** @wq: wait queue for g2h chanenl */
• wait_queue_head_t wq;
• struct { u16 last_fence; /* last fence used to send request */

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 ae0b386467e3..0ff7dd6d337d 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -253,6 +253,74 @@ static inline void set_lrc_desc_registered(struct intel_guc *guc, u32 id, xa_store_irq(&guc->context_lookup, id, ce, GFP_ATOMIC); }

+static int guc_submission_busy_loop(struct intel_guc* guc,

• 		    const u32 *action,
  

• 		    u32 len,
  

• 		    u32 g2h_len_dw,
  

• 		    bool loop)
  

+{

• int err;
• err = intel_guc_send_busy_loop(guc, action, len, g2h_len_dw, loop);
• if (!err && g2h_len_dw)

• atomic_inc(&guc->outstanding_submission_g2h);
  

• return err;

+}

+static int guc_wait_for_pending_msg(struct intel_guc *guc,

• 		    atomic_t *wait_var,
  

• 		    bool interruptible,
  

• 		    long timeout)
  

+{

• const int state = interruptible ?

• TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
  

• DEFINE_WAIT(wait);
• might_sleep();
• GEM_BUG_ON(timeout < 0);
• if (!atomic_read(wait_var))

• return 0;
  

• if (!timeout)

• return -ETIME;
  

• for (;;) {

• prepare_to_wait(&guc->ct.wq, &wait, state);
  

• if (!atomic_read(wait_var))
  

• 	break;
  

• if (signal_pending_state(state, current)) {
  

• 	timeout = -ERESTARTSYS;
  

• 	break;
  

• }
  

• if (!timeout) {
  

• 	timeout = -ETIME;
  

• 	break;
  

• }
  

• timeout = io_schedule_timeout(timeout);
  

• }
• finish_wait(&guc->ct.wq, &wait);
• return (timeout < 0) ? timeout : 0;

+}

See if it is possible to simplify all this with wait_var_event and wake_up_var.

+int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout) +{

• bool interruptible = true;
• if (unlikely(timeout < 0))

• timeout = -timeout, interruptible = false;
  

• return guc_wait_for_pending_msg(guc, &guc->outstanding_submission_g2h,

• 			interruptible, timeout);
  

+}

• static int guc_add_request(struct intel_guc *guc, struct i915_request *rq) { int err;

@@ -279,6 +347,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)

err = intel_guc_send_nb(guc, action, len, g2h_len_dw); if (!enabled && !err) {

• atomic_inc(&guc->outstanding_submission_g2h);
  

  set_context_enabled(ce); } else if (!enabled) { clr_context_pending_enable(ce);

@@ -734,7 +803,7 @@ static int __guc_action_register_context(struct intel_guc *guc, offset, };

• return intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action), 0, true);

• return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), 0, true); }

  static int register_context(struct intel_context *ce)

@@ -754,7 +823,7 @@ static int __guc_action_deregister_context(struct intel_guc *guc, guc_id, };

• return intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action),

• return guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), G2H_LEN_DW_DEREGISTER_CONTEXT, true); }

@@ -871,7 +940,9 @@ static int guc_context_pin(struct intel_context *ce, void *vaddr)

static void guc_context_unpin(struct intel_context *ce) {

• unpin_guc_id(ce_to_guc(ce), ce);

• struct intel_guc *guc = ce_to_guc(ce);
• unpin_guc_id(guc, ce); lrc_unpin(ce); }

@@ -894,7 +965,7 @@ static void __guc_context_sched_disable(struct intel_guc *guc,

intel_context_get(ce);

• intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action),

• guc_submission_busy_loop(guc, action, ARRAY_SIZE(action), G2H_LEN_DW_SCHED_CONTEXT_MODE_SET, true); }

@@ -1437,6 +1508,15 @@ g2h_context_lookup(struct intel_guc *guc, u32 desc_idx) return ce; }

+static void decr_outstanding_submission_g2h(struct intel_guc *guc) +{

• if (atomic_dec_and_test(&guc->outstanding_submission_g2h)) {

• smp_mb();
  

• if (waitqueue_active(&guc->ct.wq))
  

• 	wake_up_all(&guc->ct.wq);
  

I keep pointing out this pattern is racy and at least needs comment why it is safe.

Regards,

Tvrtko

• }

+}

• int intel_guc_deregister_done_process_msg(struct intel_guc *guc, const u32 *msg, u32 len)

@@ -1472,6 +1552,8 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc, lrc_destroy(&ce->ref); }

• decr_outstanding_submission_g2h(guc);
• return 0; }

@@ -1520,6 +1602,7 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc, spin_unlock_irqrestore(&ce->guc_state.lock, flags); }

• decr_outstanding_submission_g2h(guc); intel_context_put(ce);

  return 0;

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h b/drivers/gpu/drm/i915/gt/uc/intel_uc.h index 9c954c589edf..c4cef885e984 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h @@ -81,6 +81,11 @@ uc_state_checkers(guc, guc_submission); #undef uc_state_checkers #undef __uc_state_checker

+static inline int intel_uc_wait_for_idle(struct intel_uc *uc, long timeout) +{

• return intel_guc_wait_for_idle(&uc->guc, timeout);

+}

• #define intel_uc_ops_function(_NAME, _OPS, _TYPE, _RET) \ static inline _TYPE intel_uc_##_NAME(struct intel_uc *uc) \ { \

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 8dd374691102..bb29838d1cd7 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -36,6 +36,7 @@ #include "gt/intel_gt_clock_utils.h" #include "gt/intel_gt.h" #include "gt/intel_gt_pm.h" +#include "gt/intel_gt.h" #include "gt/intel_gt_requests.h" #include "gt/intel_reset.h" #include "gt/intel_rc6.h" diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c index 4d2d59a9942b..2b73ddb11c66 100644 --- a/drivers/gpu/drm/i915/i915_gem_evict.c +++ b/drivers/gpu/drm/i915/i915_gem_evict.c @@ -27,6 +27,7 @@ */

#include "gem/i915_gem_context.h" +#include "gt/intel_gt.h" #include "gt/intel_gt_requests.h"

#include "i915_drv.h" diff --git a/drivers/gpu/drm/i915/selftests/igt_live_test.c b/drivers/gpu/drm/i915/selftests/igt_live_test.c index c130010a7033..1c721542e277 100644 --- a/drivers/gpu/drm/i915/selftests/igt_live_test.c +++ b/drivers/gpu/drm/i915/selftests/igt_live_test.c @@ -5,7 +5,7 @@ */

#include "i915_drv.h" -#include "gt/intel_gt_requests.h" +#include "gt/intel_gt.h"

#include "../i915_selftest.h" #include "igt_flush_test.h" diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c index cf40004bc92a..6c06816e2b99 100644 --- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c +++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c @@ -51,7 +51,8 @@ void mock_device_flush(struct drm_i915_private *i915) do { for_each_engine(engine, gt, id) mock_engine_flush(engine);

• } while (intel_gt_retire_requests_timeout(gt, MAX_SCHEDULE_TIMEOUT));

• } while (intel_gt_retire_requests_timeout(gt, MAX_SCHEDULE_TIMEOUT,

• 				  NULL));
  

  }

  static void mock_device_release(struct drm_device *dev)