From: Chris Wilson Date: Wed, 13 Apr 2016 16:35:14 +0000 (+0100) Subject: drm/i915: Reorganise legacy context switch to cope with late failure X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=fcb5106d665879edbc1ebb6e1f1a67695954b81d;p=linux-beck.git drm/i915: Reorganise legacy context switch to cope with late failure After mi_set_context() succeeds, we need to update the state of the engine's last_context. This ensures that we hold a pin on the context whilst the hardware may write to it. However, since we didn't complete the post-switch setup of the context, we need to force the subsequent use of the same context to complete the setup (which means updating should_skip_switch()). Signed-off-by: Chris Wilson Cc: Daniel Vetter Cc: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/1460565315-7748-15-git-send-email-chris@chris-wilson.co.uk --- diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index c027240aacf3..e5acc3916f75 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -610,17 +610,19 @@ mi_set_context(struct drm_i915_gem_request *req, u32 hw_flags) } static inline bool skip_rcs_switch(struct intel_engine_cs *engine, - struct intel_context *from, struct intel_context *to) { if (to->remap_slice) return false; - if (to->ppgtt && from == to && + if (!to->legacy_hw_ctx.initialized) + return false; + + if (to->ppgtt && !(intel_engine_flag(engine) & to->ppgtt->pd_dirty_rings)) - return true; + return false; - return false; + return to == engine->last_context; } static bool @@ -643,18 +645,12 @@ needs_pd_load_pre(struct intel_engine_cs *engine, struct intel_context *to) } static bool -needs_pd_load_post(struct intel_engine_cs *engine, struct intel_context *to, - u32 hw_flags) +needs_pd_load_post(struct intel_context *to, u32 hw_flags) { - struct drm_i915_private *dev_priv = engine->dev->dev_private; - if (!to->ppgtt) return false; - if (!IS_GEN8(engine->dev)) - return false; - - if (engine != &dev_priv->engine[RCS]) + if (!IS_GEN8(to->i915)) return false; if (hw_flags & MI_RESTORE_INHIBIT) @@ -667,12 +663,11 @@ static int do_rcs_switch(struct drm_i915_gem_request *req) { struct intel_context *to = req->ctx; struct intel_engine_cs *engine = req->engine; - struct intel_context *from = engine->last_context; - u32 hw_flags = 0; - bool uninitialized = false; + struct intel_context *from; + u32 hw_flags; int ret, i; - if (skip_rcs_switch(engine, from, to)) + if (skip_rcs_switch(engine, to)) return 0; /* Trying to pin first makes error handling easier. */ @@ -686,23 +681,11 @@ static int do_rcs_switch(struct drm_i915_gem_request *req) * Pin can switch back to the default context if we end up calling into * evict_everything - as a last ditch gtt defrag effort that also * switches to the default context. Hence we need to reload from here. + * + * XXX: Doing so is painfully broken! */ from = engine->last_context; - if (needs_pd_load_pre(engine, to)) { - /* Older GENs and non render rings still want the load first, - * "PP_DCLV followed by PP_DIR_BASE register through Load - * Register Immediate commands in Ring Buffer before submitting - * a context."*/ - trace_switch_mm(engine, to); - ret = to->ppgtt->switch_mm(to->ppgtt, req); - if (ret) - goto unpin_out; - - /* Doing a PD load always reloads the page dirs */ - to->ppgtt->pd_dirty_rings &= ~intel_engine_flag(engine); - } - /* * Clear this page out of any CPU caches for coherent swap-in/out. Note * that thanks to write = false in this call and us not setting any gpu @@ -715,53 +698,37 @@ static int do_rcs_switch(struct drm_i915_gem_request *req) if (ret) goto unpin_out; - if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) { - hw_flags |= MI_RESTORE_INHIBIT; + if (needs_pd_load_pre(engine, to)) { + /* Older GENs and non render rings still want the load first, + * "PP_DCLV followed by PP_DIR_BASE register through Load + * Register Immediate commands in Ring Buffer before submitting + * a context."*/ + trace_switch_mm(engine, to); + ret = to->ppgtt->switch_mm(to->ppgtt, req); + if (ret) + goto unpin_out; + } + + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) /* NB: If we inhibit the restore, the context is not allowed to * die because future work may end up depending on valid address * space. This means we must enforce that a page table load * occur when this occurs. */ - } else if (to->ppgtt && - (intel_engine_flag(engine) & to->ppgtt->pd_dirty_rings)) { - hw_flags |= MI_FORCE_RESTORE; - to->ppgtt->pd_dirty_rings &= ~intel_engine_flag(engine); - } + hw_flags = MI_RESTORE_INHIBIT; + else if (to->ppgtt && + intel_engine_flag(engine) & to->ppgtt->pd_dirty_rings) + hw_flags = MI_FORCE_RESTORE; + else + hw_flags = 0; /* We should never emit switch_mm more than once */ WARN_ON(needs_pd_load_pre(engine, to) && - needs_pd_load_post(engine, to, hw_flags)); - - ret = mi_set_context(req, hw_flags); - if (ret) - goto unpin_out; + needs_pd_load_post(to, hw_flags)); - /* GEN8 does *not* require an explicit reload if the PDPs have been - * setup, and we do not wish to move them. - */ - if (needs_pd_load_post(engine, to, hw_flags)) { - trace_switch_mm(engine, to); - ret = to->ppgtt->switch_mm(to->ppgtt, req); - /* The hardware context switch is emitted, but we haven't - * actually changed the state - so it's probably safe to bail - * here. Still, let the user know something dangerous has - * happened. - */ - if (ret) { - DRM_ERROR("Failed to change address space on context switch\n"); - goto unpin_out; - } - } - - for (i = 0; i < MAX_L3_SLICES; i++) { - if (!(to->remap_slice & (1<remap_slice &= ~(1<legacy_hw_ctx.rcs_state); i915_gem_context_unreference(from); } - - uninitialized = !to->legacy_hw_ctx.initialized; - to->legacy_hw_ctx.initialized = true; - i915_gem_context_reference(to); engine->last_context = to; - if (uninitialized) { + /* GEN8 does *not* require an explicit reload if the PDPs have been + * setup, and we do not wish to move them. + */ + if (needs_pd_load_post(to, hw_flags)) { + trace_switch_mm(engine, to); + ret = to->ppgtt->switch_mm(to->ppgtt, req); + /* The hardware context switch is emitted, but we haven't + * actually changed the state - so it's probably safe to bail + * here. Still, let the user know something dangerous has + * happened. + */ + if (ret) + return ret; + } + + if (to->ppgtt) + to->ppgtt->pd_dirty_rings &= ~intel_engine_flag(engine); + + for (i = 0; i < MAX_L3_SLICES; i++) { + if (!(to->remap_slice & (1<remap_slice &= ~(1<legacy_hw_ctx.initialized) { if (engine->init_context) { ret = engine->init_context(req); if (ret) - DRM_ERROR("ring init context: %d\n", ret); + return ret; } + to->legacy_hw_ctx.initialized = true; } return 0;