diff options
Diffstat (limited to 'drivers/gpu/drm/i915/i915_request.h')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_request.h | 496 |
1 files changed, 91 insertions, 405 deletions
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index d014b0605445..40f3e8dcbdd5 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -38,23 +38,34 @@ struct drm_i915_gem_object; struct i915_request; struct i915_timeline; -struct intel_wait { - struct rb_node node; - struct task_struct *tsk; - struct i915_request *request; - u32 seqno; -}; - -struct intel_signal_node { - struct intel_wait wait; - struct list_head link; -}; - struct i915_capture_list { struct i915_capture_list *next; struct i915_vma *vma; }; +enum { + /* + * I915_FENCE_FLAG_ACTIVE - this request is currently submitted to HW. + * + * Set by __i915_request_submit() on handing over to HW, and cleared + * by __i915_request_unsubmit() if we preempt this request. + * + * Finally cleared for consistency on retiring the request, when + * we know the HW is no longer running this request. + * + * See i915_request_is_active() + */ + I915_FENCE_FLAG_ACTIVE = DMA_FENCE_FLAG_USER_BITS, + + /* + * I915_FENCE_FLAG_SIGNAL - this request is currently on signal_list + * + * Internal bookkeeping used by the breadcrumb code to track when + * a request is on the various signal_list. + */ + I915_FENCE_FLAG_SIGNAL, +}; + /** * Request queue structure. * @@ -97,7 +108,7 @@ struct i915_request { struct intel_context *hw_context; struct intel_ring *ring; struct i915_timeline *timeline; - struct intel_signal_node signaling; + struct list_head signal_link; /* * The rcu epoch of when this request was allocated. Used to judiciously @@ -116,7 +127,6 @@ struct i915_request { */ struct i915_sw_fence submit; wait_queue_entry_t submitq; - wait_queue_head_t execute; /* * A list of everyone we wait upon, and everyone who waits upon us. @@ -130,6 +140,13 @@ struct i915_request { struct i915_sched_node sched; struct i915_dependency dep; + /* + * A convenience pointer to the current breadcrumb value stored in + * the HW status page (or our timeline's local equivalent). The full + * path would be rq->hw_context->ring->timeline->hwsp_seqno. + */ + const u32 *hwsp_seqno; + /** * GEM sequence number associated with this request on the * global execution timeline. It is zero when the request is not @@ -248,7 +265,7 @@ i915_request_put(struct i915_request *rq) * that it has passed the global seqno and the global seqno is unchanged * after the read, it is indeed complete). */ -static u32 +static inline u32 i915_request_global_seqno(const struct i915_request *request) { return READ_ONCE(request->global_seqno); @@ -270,6 +287,10 @@ void i915_request_skip(struct i915_request *request, int error); void __i915_request_unsubmit(struct i915_request *request); void i915_request_unsubmit(struct i915_request *request); +/* Note: part of the intel_breadcrumbs family */ +bool i915_request_enable_breadcrumb(struct i915_request *request); +void i915_request_cancel_breadcrumb(struct i915_request *request); + long i915_request_wait(struct i915_request *rq, unsigned int flags, long timeout) @@ -280,441 +301,106 @@ long i915_request_wait(struct i915_request *rq, #define I915_WAIT_ALL BIT(3) /* used by i915_gem_object_wait() */ #define I915_WAIT_FOR_IDLE_BOOST BIT(4) -static inline bool intel_engine_has_started(struct intel_engine_cs *engine, - u32 seqno); -static inline bool intel_engine_has_completed(struct intel_engine_cs *engine, - u32 seqno); - -/** - * Returns true if seq1 is later than seq2. - */ -static inline bool i915_seqno_passed(u32 seq1, u32 seq2) -{ - return (s32)(seq1 - seq2) >= 0; -} - -/** - * i915_request_started - check if the request has begun being executed - * @rq: the request - * - * Returns true if the request has been submitted to hardware, and the hardware - * has advanced passed the end of the previous request and so should be either - * currently processing the request (though it may be preempted and so - * not necessarily the next request to complete) or have completed the request. - */ -static inline bool i915_request_started(const struct i915_request *rq) -{ - u32 seqno; - - seqno = i915_request_global_seqno(rq); - if (!seqno) /* not yet submitted to HW */ - return false; - - return intel_engine_has_started(rq->engine, seqno); -} - -static inline bool -__i915_request_completed(const struct i915_request *rq, u32 seqno) -{ - GEM_BUG_ON(!seqno); - return intel_engine_has_completed(rq->engine, seqno) && - seqno == i915_request_global_seqno(rq); -} - -static inline bool i915_request_completed(const struct i915_request *rq) -{ - u32 seqno; - - seqno = i915_request_global_seqno(rq); - if (!seqno) - return false; - - return __i915_request_completed(rq, seqno); -} - -void i915_retire_requests(struct drm_i915_private *i915); - -/* - * We treat requests as fences. This is not be to confused with our - * "fence registers" but pipeline synchronisation objects ala GL_ARB_sync. - * We use the fences to synchronize access from the CPU with activity on the - * GPU, for example, we should not rewrite an object's PTE whilst the GPU - * is reading them. We also track fences at a higher level to provide - * implicit synchronisation around GEM objects, e.g. set-domain will wait - * for outstanding GPU rendering before marking the object ready for CPU - * access, or a pageflip will wait until the GPU is complete before showing - * the frame on the scanout. - * - * In order to use a fence, the object must track the fence it needs to - * serialise with. For example, GEM objects want to track both read and - * write access so that we can perform concurrent read operations between - * the CPU and GPU engines, as well as waiting for all rendering to - * complete, or waiting for the last GPU user of a "fence register". The - * object then embeds a #i915_gem_active to track the most recent (in - * retirement order) request relevant for the desired mode of access. - * The #i915_gem_active is updated with i915_gem_active_set() to track the - * most recent fence request, typically this is done as part of - * i915_vma_move_to_active(). - * - * When the #i915_gem_active completes (is retired), it will - * signal its completion to the owner through a callback as well as mark - * itself as idle (i915_gem_active.request == NULL). The owner - * can then perform any action, such as delayed freeing of an active - * resource including itself. - */ -struct i915_gem_active; - -typedef void (*i915_gem_retire_fn)(struct i915_gem_active *, - struct i915_request *); - -struct i915_gem_active { - struct i915_request __rcu *request; - struct list_head link; - i915_gem_retire_fn retire; -}; - -void i915_gem_retire_noop(struct i915_gem_active *, - struct i915_request *request); - -/** - * init_request_active - prepares the activity tracker for use - * @active - the active tracker - * @func - a callback when then the tracker is retired (becomes idle), - * can be NULL - * - * init_request_active() prepares the embedded @active struct for use as - * an activity tracker, that is for tracking the last known active request - * associated with it. When the last request becomes idle, when it is retired - * after completion, the optional callback @func is invoked. - */ -static inline void -init_request_active(struct i915_gem_active *active, - i915_gem_retire_fn retire) +static inline bool i915_request_signaled(const struct i915_request *rq) { - RCU_INIT_POINTER(active->request, NULL); - INIT_LIST_HEAD(&active->link); - active->retire = retire ?: i915_gem_retire_noop; + /* The request may live longer than its HWSP, so check flags first! */ + return test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &rq->fence.flags); } -/** - * i915_gem_active_set - updates the tracker to watch the current request - * @active - the active tracker - * @request - the request to watch - * - * i915_gem_active_set() watches the given @request for completion. Whilst - * that @request is busy, the @active reports busy. When that @request is - * retired, the @active tracker is updated to report idle. - */ -static inline void -i915_gem_active_set(struct i915_gem_active *active, - struct i915_request *request) +static inline bool i915_request_is_active(const struct i915_request *rq) { - list_move(&active->link, &request->active_list); - rcu_assign_pointer(active->request, request); + return test_bit(I915_FENCE_FLAG_ACTIVE, &rq->fence.flags); } /** - * i915_gem_active_set_retire_fn - updates the retirement callback - * @active - the active tracker - * @fn - the routine called when the request is retired - * @mutex - struct_mutex used to guard retirements - * - * i915_gem_active_set_retire_fn() updates the function pointer that - * is called when the final request associated with the @active tracker - * is retired. + * Returns true if seq1 is later than seq2. */ -static inline void -i915_gem_active_set_retire_fn(struct i915_gem_active *active, - i915_gem_retire_fn fn, - struct mutex *mutex) +static inline bool i915_seqno_passed(u32 seq1, u32 seq2) { - lockdep_assert_held(mutex); - active->retire = fn ?: i915_gem_retire_noop; + return (s32)(seq1 - seq2) >= 0; } -static inline struct i915_request * -__i915_gem_active_peek(const struct i915_gem_active *active) +static inline u32 __hwsp_seqno(const struct i915_request *rq) { - /* - * Inside the error capture (running with the driver in an unknown - * state), we want to bend the rules slightly (a lot). - * - * Work is in progress to make it safer, in the meantime this keeps - * the known issue from spamming the logs. - */ - return rcu_dereference_protected(active->request, 1); + return READ_ONCE(*rq->hwsp_seqno); } /** - * i915_gem_active_raw - return the active request - * @active - the active tracker + * hwsp_seqno - the current breadcrumb value in the HW status page + * @rq: the request, to chase the relevant HW status page * - * i915_gem_active_raw() returns the current request being tracked, or NULL. - * It does not obtain a reference on the request for the caller, so the caller - * must hold struct_mutex. - */ -static inline struct i915_request * -i915_gem_active_raw(const struct i915_gem_active *active, struct mutex *mutex) -{ - return rcu_dereference_protected(active->request, - lockdep_is_held(mutex)); -} - -/** - * i915_gem_active_peek - report the active request being monitored - * @active - the active tracker + * The emphasis in naming here is that hwsp_seqno() is not a property of the + * request, but an indication of the current HW state (associated with this + * request). Its value will change as the GPU executes more requests. * - * i915_gem_active_peek() returns the current request being tracked if - * still active, or NULL. It does not obtain a reference on the request - * for the caller, so the caller must hold struct_mutex. + * Returns the current breadcrumb value in the associated HW status page (or + * the local timeline's equivalent) for this request. The request itself + * has the associated breadcrumb value of rq->fence.seqno, when the HW + * status page has that breadcrumb or later, this request is complete. */ -static inline struct i915_request * -i915_gem_active_peek(const struct i915_gem_active *active, struct mutex *mutex) +static inline u32 hwsp_seqno(const struct i915_request *rq) { - struct i915_request *request; + u32 seqno; - request = i915_gem_active_raw(active, mutex); - if (!request || i915_request_completed(request)) - return NULL; + rcu_read_lock(); /* the HWSP may be freed at runtime */ + seqno = __hwsp_seqno(rq); + rcu_read_unlock(); - return request; + return seqno; } -/** - * i915_gem_active_get - return a reference to the active request - * @active - the active tracker - * - * i915_gem_active_get() returns a reference to the active request, or NULL - * if the active tracker is idle. The caller must hold struct_mutex. - */ -static inline struct i915_request * -i915_gem_active_get(const struct i915_gem_active *active, struct mutex *mutex) +static inline bool __i915_request_has_started(const struct i915_request *rq) { - return i915_request_get(i915_gem_active_peek(active, mutex)); + return i915_seqno_passed(hwsp_seqno(rq), rq->fence.seqno - 1); } /** - * __i915_gem_active_get_rcu - return a reference to the active request - * @active - the active tracker - * - * __i915_gem_active_get() returns a reference to the active request, or NULL - * if the active tracker is idle. The caller must hold the RCU read lock, but - * the returned pointer is safe to use outside of RCU. - */ -static inline struct i915_request * -__i915_gem_active_get_rcu(const struct i915_gem_active *active) -{ - /* - * Performing a lockless retrieval of the active request is super - * tricky. SLAB_TYPESAFE_BY_RCU merely guarantees that the backing - * slab of request objects will not be freed whilst we hold the - * RCU read lock. It does not guarantee that the request itself - * will not be freed and then *reused*. Viz, - * - * Thread A Thread B - * - * rq = active.request - * retire(rq) -> free(rq); - * (rq is now first on the slab freelist) - * active.request = NULL - * - * rq = new submission on a new object - * ref(rq) - * - * To prevent the request from being reused whilst the caller - * uses it, we take a reference like normal. Whilst acquiring - * the reference we check that it is not in a destroyed state - * (refcnt == 0). That prevents the request being reallocated - * whilst the caller holds on to it. To check that the request - * was not reallocated as we acquired the reference we have to - * check that our request remains the active request across - * the lookup, in the same manner as a seqlock. The visibility - * of the pointer versus the reference counting is controlled - * by using RCU barriers (rcu_dereference and rcu_assign_pointer). - * - * In the middle of all that, we inspect whether the request is - * complete. Retiring is lazy so the request may be completed long - * before the active tracker is updated. Querying whether the - * request is complete is far cheaper (as it involves no locked - * instructions setting cachelines to exclusive) than acquiring - * the reference, so we do it first. The RCU read lock ensures the - * pointer dereference is valid, but does not ensure that the - * seqno nor HWS is the right one! However, if the request was - * reallocated, that means the active tracker's request was complete. - * If the new request is also complete, then both are and we can - * just report the active tracker is idle. If the new request is - * incomplete, then we acquire a reference on it and check that - * it remained the active request. - * - * It is then imperative that we do not zero the request on - * reallocation, so that we can chase the dangling pointers! - * See i915_request_alloc(). - */ - do { - struct i915_request *request; - - request = rcu_dereference(active->request); - if (!request || i915_request_completed(request)) - return NULL; - - /* - * An especially silly compiler could decide to recompute the - * result of i915_request_completed, more specifically - * re-emit the load for request->fence.seqno. A race would catch - * a later seqno value, which could flip the result from true to - * false. Which means part of the instructions below might not - * be executed, while later on instructions are executed. Due to - * barriers within the refcounting the inconsistency can't reach - * past the call to i915_request_get_rcu, but not executing - * that while still executing i915_request_put() creates - * havoc enough. Prevent this with a compiler barrier. - */ - barrier(); - - request = i915_request_get_rcu(request); - - /* - * What stops the following rcu_access_pointer() from occurring - * before the above i915_request_get_rcu()? If we were - * to read the value before pausing to get the reference to - * the request, we may not notice a change in the active - * tracker. - * - * The rcu_access_pointer() is a mere compiler barrier, which - * means both the CPU and compiler are free to perform the - * memory read without constraint. The compiler only has to - * ensure that any operations after the rcu_access_pointer() - * occur afterwards in program order. This means the read may - * be performed earlier by an out-of-order CPU, or adventurous - * compiler. - * - * The atomic operation at the heart of - * i915_request_get_rcu(), see dma_fence_get_rcu(), is - * atomic_inc_not_zero() which is only a full memory barrier - * when successful. That is, if i915_request_get_rcu() - * returns the request (and so with the reference counted - * incremented) then the following read for rcu_access_pointer() - * must occur after the atomic operation and so confirm - * that this request is the one currently being tracked. - * - * The corresponding write barrier is part of - * rcu_assign_pointer(). - */ - if (!request || request == rcu_access_pointer(active->request)) - return rcu_pointer_handoff(request); - - i915_request_put(request); - } while (1); -} - -/** - * i915_gem_active_get_unlocked - return a reference to the active request - * @active - the active tracker - * - * i915_gem_active_get_unlocked() returns a reference to the active request, - * or NULL if the active tracker is idle. The reference is obtained under RCU, - * so no locking is required by the caller. + * i915_request_started - check if the request has begun being executed + * @rq: the request * - * The reference should be freed with i915_request_put(). + * Returns true if the request has been submitted to hardware, and the hardware + * has advanced passed the end of the previous request and so should be either + * currently processing the request (though it may be preempted and so + * not necessarily the next request to complete) or have completed the request. */ -static inline struct i915_request * -i915_gem_active_get_unlocked(const struct i915_gem_active *active) +static inline bool i915_request_started(const struct i915_request *rq) { - struct i915_request *request; + if (i915_request_signaled(rq)) + return true; - rcu_read_lock(); - request = __i915_gem_active_get_rcu(active); - rcu_read_unlock(); - - return request; + /* Remember: started but may have since been preempted! */ + return __i915_request_has_started(rq); } /** - * i915_gem_active_isset - report whether the active tracker is assigned - * @active - the active tracker + * i915_request_is_running - check if the request may actually be executing + * @rq: the request * - * i915_gem_active_isset() returns true if the active tracker is currently - * assigned to a request. Due to the lazy retiring, that request may be idle - * and this may report stale information. + * Returns true if the request is currently submitted to hardware, has passed + * its start point (i.e. the context is setup and not busywaiting). Note that + * it may no longer be running by the time the function returns! */ -static inline bool -i915_gem_active_isset(const struct i915_gem_active *active) +static inline bool i915_request_is_running(const struct i915_request *rq) { - return rcu_access_pointer(active->request); + if (!i915_request_is_active(rq)) + return false; + + return __i915_request_has_started(rq); } -/** - * i915_gem_active_wait - waits until the request is completed - * @active - the active request on which to wait - * @flags - how to wait - * @timeout - how long to wait at most - * @rps - userspace client to charge for a waitboost - * - * i915_gem_active_wait() waits until the request is completed before - * returning, without requiring any locks to be held. Note that it does not - * retire any requests before returning. - * - * This function relies on RCU in order to acquire the reference to the active - * request without holding any locks. See __i915_gem_active_get_rcu() for the - * glory details on how that is managed. Once the reference is acquired, we - * can then wait upon the request, and afterwards release our reference, - * free of any locking. - * - * This function wraps i915_request_wait(), see it for the full details on - * the arguments. - * - * Returns 0 if successful, or a negative error code. - */ -static inline int -i915_gem_active_wait(const struct i915_gem_active *active, unsigned int flags) +static inline bool i915_request_completed(const struct i915_request *rq) { - struct i915_request *request; - long ret = 0; - - request = i915_gem_active_get_unlocked(active); - if (request) { - ret = i915_request_wait(request, flags, MAX_SCHEDULE_TIMEOUT); - i915_request_put(request); - } + if (i915_request_signaled(rq)) + return true; - return ret < 0 ? ret : 0; + return i915_seqno_passed(hwsp_seqno(rq), rq->fence.seqno); } -/** - * i915_gem_active_retire - waits until the request is retired - * @active - the active request on which to wait - * - * i915_gem_active_retire() waits until the request is completed, - * and then ensures that at least the retirement handler for this - * @active tracker is called before returning. If the @active - * tracker is idle, the function returns immediately. - */ -static inline int __must_check -i915_gem_active_retire(struct i915_gem_active *active, - struct mutex *mutex) +static inline void i915_request_mark_complete(struct i915_request *rq) { - struct i915_request *request; - long ret; - - request = i915_gem_active_raw(active, mutex); - if (!request) - return 0; - - ret = i915_request_wait(request, - I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED, - MAX_SCHEDULE_TIMEOUT); - if (ret < 0) - return ret; - - list_del_init(&active->link); - RCU_INIT_POINTER(active->request, NULL); - - active->retire(active, request); - - return 0; + rq->hwsp_seqno = (u32 *)&rq->fence.seqno; /* decouple from HWSP */ } -#define for_each_active(mask, idx) \ - for (; mask ? idx = ffs(mask) - 1, 1 : 0; mask &= ~BIT(idx)) +void i915_retire_requests(struct drm_i915_private *i915); #endif /* I915_REQUEST_H */ |