From e8a9c58fcd9a5081f71f57f370af1347ed6a310b Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sun, 18 Dec 2016 15:37:20 +0000 Subject: drm/i915: Unify active context tracking between legacy/execlists/guc The requests conversion introduced a nasty bug where we could generate a new request in the middle of constructing a request if we needed to idle the system in order to evict space for a context. The request to idle would be executed (and waited upon) before the current one, creating a minor havoc in the seqno accounting, as we will consider the current request to already be completed (prior to deferred seqno assignment) but ring->last_retired_head would have been updated and still could allow us to overwrite the current request before execution. We also employed two different mechanisms to track the active context until it was switched out. The legacy method allowed for waiting upon an active context (it could forcibly evict any vma, including context's), but the execlists method took a step backwards by pinning the vma for the entire active lifespan of the context (the only way to evict was to idle the entire GPU, not individual contexts). However, to circumvent the tricky issue of locking (i.e. we cannot take struct_mutex at the time of i915_gem_request_submit(), where we would want to move the previous context onto the active tracker and unpin it), we take the execlists approach and keep the contexts pinned until retirement. The benefit of the execlists approach, more important for execlists than legacy, was the reduction in work in pinning the context for each request - as the context was kept pinned until idle, it could short circuit the pinning for all active contexts. We introduce new engine vfuncs to pin and unpin the context respectively. The context is pinned at the start of the request, and only unpinned when the following request is retired (this ensures that the context is idle and coherent in main memory before we unpin it). We move the engine->last_context tracking into the retirement itself (rather than during request submission) in order to allow the submission to be reordered or unwound without undue difficultly. And finally an ulterior motive for unifying context handling was to prepare for mock requests. v2: Rename to last_retired_context, split out legacy_context tracking for MI_SET_CONTEXT. Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/20161218153724.8439-3-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_request.h | 11 ----------- 1 file changed, 11 deletions(-) (limited to 'drivers/gpu/drm/i915/i915_gem_request.h') diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h index e2b077df2da0..8569b35a332a 100644 --- a/drivers/gpu/drm/i915/i915_gem_request.h +++ b/drivers/gpu/drm/i915/i915_gem_request.h @@ -170,17 +170,6 @@ struct drm_i915_gem_request { /** Preallocate space in the ring for the emitting the request */ u32 reserved_space; - /** - * Context related to the previous request. - * As the contexts are accessed by the hardware until the switch is - * completed to a new context, the hardware may still be writing - * to the context object after the breadcrumb is visible. We must - * not unpin/unbind/prune that object whilst still active and so - * we keep the previous context pinned until the following (this) - * request is retired. - */ - struct i915_gem_context *previous_context; - /** Batch buffer related to this request if any (used for * error state dump only). */ -- cgit From ecd9caa0522db5a6b03ac8858c42067ef9d8323b Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Wed, 7 Dec 2016 17:56:47 +0000 Subject: drm/i915: Fix oopses in the overlay code due to i915_gem_active stuff MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The i915_gem_active stuff doesn't like a NULL ->retire hook, but the overlay code can set it to NULL. That obviously ends up oopsing. Fix it by introducing a new helper to assign the retirement callback that will switch out the NULL function pointer with i915_gem_retire_noop. Cc: stable@vger.kernel.org Cc: Chris Wilson Cc: Joonas Lahtinen Fixes: 0d9bdd886f29 ("drm/i915: Convert intel_overlay to request tracking") Signed-off-by: Ville Syrjälä Signed-off-by: Chris Wilson Link: http://patchwork.freedesktop.org/patch/msgid/20161207175647.10018-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_request.h | 19 +++++++++++++++++++ drivers/gpu/drm/i915/intel_overlay.c | 3 ++- 2 files changed, 21 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/i915/i915_gem_request.h') diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h index 8569b35a332a..ea511f06efaf 100644 --- a/drivers/gpu/drm/i915/i915_gem_request.h +++ b/drivers/gpu/drm/i915/i915_gem_request.h @@ -402,6 +402,25 @@ i915_gem_active_set(struct i915_gem_active *active, rcu_assign_pointer(active->request, request); } +/** + * 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. + */ +static inline void +i915_gem_active_set_retire_fn(struct i915_gem_active *active, + i915_gem_retire_fn fn, + struct mutex *mutex) +{ + lockdep_assert_held(mutex); + active->retire = fn ?: i915_gem_retire_noop; +} + static inline struct drm_i915_gem_request * __i915_gem_active_peek(const struct i915_gem_active *active) { diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c index bcfb60cbeb05..d513a059cd09 100644 --- a/drivers/gpu/drm/i915/intel_overlay.c +++ b/drivers/gpu/drm/i915/intel_overlay.c @@ -216,7 +216,8 @@ static void intel_overlay_submit_request(struct intel_overlay *overlay, { GEM_BUG_ON(i915_gem_active_peek(&overlay->last_flip, &overlay->i915->drm.struct_mutex)); - overlay->last_flip.retire = retire; + i915_gem_active_set_retire_fn(&overlay->last_flip, retire, + &overlay->i915->drm.struct_mutex); i915_gem_active_set(&overlay->last_flip, req); i915_add_request(req); } -- cgit