2 * Copyright © 2011-2012 Intel Corporation
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * Ben Widawsky <ben@bwidawsk.net>
29 * This file implements HW context support. On gen5+ a HW context consists of an
30 * opaque GPU object which is referenced at times of context saves and restores.
31 * With RC6 enabled, the context is also referenced as the GPU enters and exists
32 * from RC6 (GPU has it's own internal power context, except on gen5). Though
33 * something like a context does exist for the media ring, the code only
34 * supports contexts for the render ring.
36 * In software, there is a distinction between contexts created by the user,
37 * and the default HW context. The default HW context is used by GPU clients
38 * that do not request setup of their own hardware context. The default
39 * context's state is never restored to help prevent programming errors. This
40 * would happen if a client ran and piggy-backed off another clients GPU state.
41 * The default context only exists to give the GPU some offset to load as the
42 * current to invoke a save of the context we actually care about. In fact, the
43 * code could likely be constructed, albeit in a more complicated fashion, to
44 * never use the default context, though that limits the driver's ability to
45 * swap out, and/or destroy other contexts.
47 * All other contexts are created as a request by the GPU client. These contexts
48 * store GPU state, and thus allow GPU clients to not re-emit state (and
49 * potentially query certain state) at any time. The kernel driver makes
50 * certain that the appropriate commands are inserted.
52 * The context life cycle is semi-complicated in that context BOs may live
53 * longer than the context itself because of the way the hardware, and object
54 * tracking works. Below is a very crude representation of the state machine
55 * describing the context life.
56 * refcount pincount active
57 * S0: initial state 0 0 0
58 * S1: context created 1 0 0
59 * S2: context is currently running 2 1 X
60 * S3: GPU referenced, but not current 2 0 1
61 * S4: context is current, but destroyed 1 1 0
62 * S5: like S3, but destroyed 1 0 1
64 * The most common (but not all) transitions:
65 * S0->S1: client creates a context
66 * S1->S2: client submits execbuf with context
67 * S2->S3: other clients submits execbuf with context
68 * S3->S1: context object was retired
69 * S3->S2: clients submits another execbuf
70 * S2->S4: context destroy called with current context
71 * S3->S5->S0: destroy path
72 * S4->S5->S0: destroy path on current context
74 * There are two confusing terms used above:
75 * The "current context" means the context which is currently running on the
76 * GPU. The GPU has loaded its state already and has stored away the gtt
77 * offset of the BO. The GPU is not actively referencing the data at this
78 * offset, but it will on the next context switch. The only way to avoid this
79 * is to do a GPU reset.
81 * An "active context' is one which was previously the "current context" and is
82 * on the active list waiting for the next context switch to occur. Until this
83 * happens, the object must remain at the same gtt offset. It is therefore
84 * possible to destroy a context, but it is still active.
89 #include <drm/i915_drm.h>
92 /* This is a HW constraint. The value below is the largest known requirement
93 * I've seen in a spec to date, and that was a workaround for a non-shipping
94 * part. It should be safe to decrease this, but it's more future proof as is.
96 #define GEN6_CONTEXT_ALIGN (64<<10)
97 #define GEN7_CONTEXT_ALIGN 4096
99 static void do_ppgtt_cleanup(struct i915_hw_ppgtt *ppgtt)
101 struct drm_device *dev = ppgtt->base.dev;
102 struct drm_i915_private *dev_priv = dev->dev_private;
103 struct i915_address_space *vm = &ppgtt->base;
105 if (ppgtt == dev_priv->mm.aliasing_ppgtt ||
106 (list_empty(&vm->active_list) && list_empty(&vm->inactive_list))) {
107 ppgtt->base.cleanup(&ppgtt->base);
112 * Make sure vmas are unbound before we take down the drm_mm
114 * FIXME: Proper refcounting should take care of this, this shouldn't be
117 if (!list_empty(&vm->active_list)) {
118 struct i915_vma *vma;
120 list_for_each_entry(vma, &vm->active_list, mm_list)
121 if (WARN_ON(list_empty(&vma->vma_link) ||
122 list_is_singular(&vma->vma_link)))
125 i915_gem_evict_vm(&ppgtt->base, true);
127 i915_gem_retire_requests(dev);
128 i915_gem_evict_vm(&ppgtt->base, false);
131 ppgtt->base.cleanup(&ppgtt->base);
134 static void ppgtt_release(struct kref *kref)
136 struct i915_hw_ppgtt *ppgtt =
137 container_of(kref, struct i915_hw_ppgtt, ref);
139 do_ppgtt_cleanup(ppgtt);
143 static size_t get_context_alignment(struct drm_device *dev)
146 return GEN6_CONTEXT_ALIGN;
148 return GEN7_CONTEXT_ALIGN;
151 static int get_context_size(struct drm_device *dev)
153 struct drm_i915_private *dev_priv = dev->dev_private;
157 switch (INTEL_INFO(dev)->gen) {
159 reg = I915_READ(CXT_SIZE);
160 ret = GEN6_CXT_TOTAL_SIZE(reg) * 64;
163 reg = I915_READ(GEN7_CXT_SIZE);
165 ret = HSW_CXT_TOTAL_SIZE;
167 ret = GEN7_CXT_TOTAL_SIZE(reg) * 64;
170 ret = GEN8_CXT_TOTAL_SIZE;
179 void i915_gem_context_free(struct kref *ctx_ref)
181 struct i915_hw_context *ctx = container_of(ctx_ref,
183 struct i915_hw_ppgtt *ppgtt = NULL;
186 /* We refcount even the aliasing PPGTT to keep the code symmetric */
187 if (USES_PPGTT(ctx->obj->base.dev))
188 ppgtt = ctx_to_ppgtt(ctx);
190 /* XXX: Free up the object before tearing down the address space, in
191 * case we're bound in the PPGTT */
192 drm_gem_object_unreference(&ctx->obj->base);
196 kref_put(&ppgtt->ref, ppgtt_release);
197 list_del(&ctx->link);
201 static struct i915_hw_ppgtt *
202 create_vm_for_ctx(struct drm_device *dev, struct i915_hw_context *ctx)
204 struct i915_hw_ppgtt *ppgtt;
207 ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
209 return ERR_PTR(-ENOMEM);
211 ret = i915_gem_init_ppgtt(dev, ppgtt);
221 static struct i915_hw_context *
222 __create_hw_context(struct drm_device *dev,
223 struct drm_i915_file_private *file_priv)
225 struct drm_i915_private *dev_priv = dev->dev_private;
226 struct i915_hw_context *ctx;
229 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
231 return ERR_PTR(-ENOMEM);
233 kref_init(&ctx->ref);
234 list_add_tail(&ctx->link, &dev_priv->context_list);
236 if (dev_priv->hw_context_size) {
237 ctx->obj = i915_gem_alloc_object(dev, dev_priv->hw_context_size);
238 if (ctx->obj == NULL) {
243 if (INTEL_INFO(dev)->gen >= 7) {
244 ret = i915_gem_object_set_cache_level(ctx->obj,
246 /* Failure shouldn't ever happen this early */
252 /* Default context will never have a file_priv */
253 if (file_priv != NULL) {
254 ret = idr_alloc(&file_priv->context_idr, ctx,
255 DEFAULT_CONTEXT_ID, 0, GFP_KERNEL);
259 ret = DEFAULT_CONTEXT_ID;
261 ctx->file_priv = file_priv;
263 /* NB: Mark all slices as needing a remap so that when the context first
264 * loads it will restore whatever remap state already exists. If there
265 * is no remap info, it will be a NOP. */
266 ctx->remap_slice = (1 << NUM_L3_SLICES(dev)) - 1;
271 i915_gem_context_unreference(ctx);
276 * The default context needs to exist per ring that uses contexts. It stores the
277 * context state of the GPU for applications that don't utilize HW contexts, as
278 * well as an idle case.
280 static struct i915_hw_context *
281 i915_gem_create_context(struct drm_device *dev,
282 struct drm_i915_file_private *file_priv,
285 const bool is_global_default_ctx = file_priv == NULL;
286 struct drm_i915_private *dev_priv = dev->dev_private;
287 struct i915_hw_context *ctx;
290 BUG_ON(!mutex_is_locked(&dev->struct_mutex));
292 ctx = __create_hw_context(dev, file_priv);
296 if (is_global_default_ctx && ctx->obj) {
297 /* We may need to do things with the shrinker which
298 * require us to immediately switch back to the default
299 * context. This can cause a problem as pinning the
300 * default context also requires GTT space which may not
301 * be available. To avoid this we always pin the default
304 ret = i915_gem_obj_ggtt_pin(ctx->obj,
305 get_context_alignment(dev), 0);
307 DRM_DEBUG_DRIVER("Couldn't pin %d\n", ret);
313 struct i915_hw_ppgtt *ppgtt = create_vm_for_ctx(dev, ctx);
315 if (IS_ERR_OR_NULL(ppgtt)) {
316 DRM_DEBUG_DRIVER("PPGTT setup failed (%ld)\n",
318 ret = PTR_ERR(ppgtt);
321 ctx->vm = &ppgtt->base;
323 /* This case is reserved for the global default context and
324 * should only happen once. */
325 if (is_global_default_ctx) {
326 if (WARN_ON(dev_priv->mm.aliasing_ppgtt)) {
331 dev_priv->mm.aliasing_ppgtt = ppgtt;
333 } else if (USES_PPGTT(dev)) {
334 /* For platforms which only have aliasing PPGTT, we fake the
335 * address space and refcounting. */
336 ctx->vm = &dev_priv->mm.aliasing_ppgtt->base;
337 kref_get(&dev_priv->mm.aliasing_ppgtt->ref);
339 ctx->vm = &dev_priv->gtt.base;
344 if (is_global_default_ctx && ctx->obj)
345 i915_gem_object_ggtt_unpin(ctx->obj);
347 i915_gem_context_unreference(ctx);
351 void i915_gem_context_reset(struct drm_device *dev)
353 struct drm_i915_private *dev_priv = dev->dev_private;
356 /* Prevent the hardware from restoring the last context (which hung) on
358 for (i = 0; i < I915_NUM_RINGS; i++) {
359 struct intel_ring_buffer *ring = &dev_priv->ring[i];
360 struct i915_hw_context *dctx = ring->default_context;
362 /* Do a fake switch to the default context */
363 if (ring->last_context == dctx)
366 if (!ring->last_context)
369 if (dctx->obj && i == RCS) {
370 WARN_ON(i915_gem_obj_ggtt_pin(dctx->obj,
371 get_context_alignment(dev), 0));
372 /* Fake a finish/inactive */
373 dctx->obj->base.write_domain = 0;
374 dctx->obj->active = 0;
377 i915_gem_context_unreference(ring->last_context);
378 i915_gem_context_reference(dctx);
379 ring->last_context = dctx;
383 int i915_gem_context_init(struct drm_device *dev)
385 struct drm_i915_private *dev_priv = dev->dev_private;
386 struct i915_hw_context *ctx;
389 /* Init should only be called once per module load. Eventually the
390 * restriction on the context_disabled check can be loosened. */
391 if (WARN_ON(dev_priv->ring[RCS].default_context))
394 if (HAS_HW_CONTEXTS(dev)) {
395 dev_priv->hw_context_size = round_up(get_context_size(dev), 4096);
396 if (dev_priv->hw_context_size > (1<<20)) {
397 DRM_DEBUG_DRIVER("Disabling HW Contexts; invalid size %d\n",
398 dev_priv->hw_context_size);
399 dev_priv->hw_context_size = 0;
403 ctx = i915_gem_create_context(dev, NULL, USES_PPGTT(dev));
405 DRM_ERROR("Failed to create default global context (error %ld)\n",
410 /* NB: RCS will hold a ref for all rings */
411 for (i = 0; i < I915_NUM_RINGS; i++)
412 dev_priv->ring[i].default_context = ctx;
414 DRM_DEBUG_DRIVER("%s context support initialized\n", dev_priv->hw_context_size ? "HW" : "fake");
418 void i915_gem_context_fini(struct drm_device *dev)
420 struct drm_i915_private *dev_priv = dev->dev_private;
421 struct i915_hw_context *dctx = dev_priv->ring[RCS].default_context;
425 /* The only known way to stop the gpu from accessing the hw context is
426 * to reset it. Do this as the very last operation to avoid confusing
427 * other code, leading to spurious errors. */
428 intel_gpu_reset(dev);
430 /* When default context is created and switched to, base object refcount
431 * will be 2 (+1 from object creation and +1 from do_switch()).
432 * i915_gem_context_fini() will be called after gpu_idle() has switched
433 * to default context. So we need to unreference the base object once
434 * to offset the do_switch part, so that i915_gem_context_unreference()
435 * can then free the base object correctly. */
436 WARN_ON(!dev_priv->ring[RCS].last_context);
437 if (dev_priv->ring[RCS].last_context == dctx) {
438 /* Fake switch to NULL context */
439 WARN_ON(dctx->obj->active);
440 i915_gem_object_ggtt_unpin(dctx->obj);
441 i915_gem_context_unreference(dctx);
442 dev_priv->ring[RCS].last_context = NULL;
446 for (i = 0; i < I915_NUM_RINGS; i++) {
447 struct intel_ring_buffer *ring = &dev_priv->ring[i];
449 if (ring->last_context)
450 i915_gem_context_unreference(ring->last_context);
452 ring->default_context = NULL;
453 ring->last_context = NULL;
456 i915_gem_object_ggtt_unpin(dctx->obj);
457 i915_gem_context_unreference(dctx);
460 int i915_gem_context_enable(struct drm_i915_private *dev_priv)
462 struct intel_ring_buffer *ring;
465 /* This is the only place the aliasing PPGTT gets enabled, which means
466 * it has to happen before we bail on reset */
467 if (dev_priv->mm.aliasing_ppgtt) {
468 struct i915_hw_ppgtt *ppgtt = dev_priv->mm.aliasing_ppgtt;
469 ppgtt->enable(ppgtt);
472 /* FIXME: We should make this work, even in reset */
473 if (i915_reset_in_progress(&dev_priv->gpu_error))
476 BUG_ON(!dev_priv->ring[RCS].default_context);
478 for_each_ring(ring, dev_priv, i) {
479 ret = i915_switch_context(ring, ring->default_context);
487 static int context_idr_cleanup(int id, void *p, void *data)
489 struct i915_hw_context *ctx = p;
491 /* Ignore the default context because close will handle it */
492 if (i915_gem_context_is_default(ctx))
495 i915_gem_context_unreference(ctx);
499 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file)
501 struct drm_i915_file_private *file_priv = file->driver_priv;
503 idr_init(&file_priv->context_idr);
505 mutex_lock(&dev->struct_mutex);
506 file_priv->private_default_ctx =
507 i915_gem_create_context(dev, file_priv, USES_FULL_PPGTT(dev));
508 mutex_unlock(&dev->struct_mutex);
510 if (IS_ERR(file_priv->private_default_ctx)) {
511 idr_destroy(&file_priv->context_idr);
512 return PTR_ERR(file_priv->private_default_ctx);
518 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file)
520 struct drm_i915_file_private *file_priv = file->driver_priv;
522 idr_for_each(&file_priv->context_idr, context_idr_cleanup, NULL);
523 idr_destroy(&file_priv->context_idr);
525 i915_gem_context_unreference(file_priv->private_default_ctx);
528 struct i915_hw_context *
529 i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id)
531 struct i915_hw_context *ctx;
533 ctx = (struct i915_hw_context *)idr_find(&file_priv->context_idr, id);
535 return ERR_PTR(-ENOENT);
541 mi_set_context(struct intel_ring_buffer *ring,
542 struct i915_hw_context *new_context,
547 /* w/a: If Flush TLB Invalidation Mode is enabled, driver must do a TLB
548 * invalidation prior to MI_SET_CONTEXT. On GEN6 we don't set the value
549 * explicitly, so we rely on the value at ring init, stored in
550 * itlb_before_ctx_switch.
552 if (IS_GEN6(ring->dev) && ring->itlb_before_ctx_switch) {
553 ret = ring->flush(ring, I915_GEM_GPU_DOMAINS, 0);
558 ret = intel_ring_begin(ring, 6);
562 /* WaProgramMiArbOnOffAroundMiSetContext:ivb,vlv,hsw */
563 if (IS_GEN7(ring->dev))
564 intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_DISABLE);
566 intel_ring_emit(ring, MI_NOOP);
568 intel_ring_emit(ring, MI_NOOP);
569 intel_ring_emit(ring, MI_SET_CONTEXT);
570 intel_ring_emit(ring, i915_gem_obj_ggtt_offset(new_context->obj) |
572 MI_SAVE_EXT_STATE_EN |
573 MI_RESTORE_EXT_STATE_EN |
576 * w/a: MI_SET_CONTEXT must always be followed by MI_NOOP
577 * WaMiSetContext_Hang:snb,ivb,vlv
579 intel_ring_emit(ring, MI_NOOP);
581 if (IS_GEN7(ring->dev))
582 intel_ring_emit(ring, MI_ARB_ON_OFF | MI_ARB_ENABLE);
584 intel_ring_emit(ring, MI_NOOP);
586 intel_ring_advance(ring);
591 static int do_switch(struct intel_ring_buffer *ring,
592 struct i915_hw_context *to)
594 struct drm_i915_private *dev_priv = ring->dev->dev_private;
595 struct i915_hw_context *from = ring->last_context;
596 struct i915_hw_ppgtt *ppgtt = ctx_to_ppgtt(to);
600 if (from != NULL && ring == &dev_priv->ring[RCS]) {
601 BUG_ON(from->obj == NULL);
602 BUG_ON(!i915_gem_obj_is_pinned(from->obj));
605 if (from == to && from->last_ring == ring && !to->remap_slice)
608 /* Trying to pin first makes error handling easier. */
609 if (ring == &dev_priv->ring[RCS]) {
610 ret = i915_gem_obj_ggtt_pin(to->obj,
611 get_context_alignment(ring->dev), 0);
617 * Pin can switch back to the default context if we end up calling into
618 * evict_everything - as a last ditch gtt defrag effort that also
619 * switches to the default context. Hence we need to reload from here.
621 from = ring->last_context;
623 if (USES_FULL_PPGTT(ring->dev)) {
624 ret = ppgtt->switch_mm(ppgtt, ring, false);
629 if (ring != &dev_priv->ring[RCS]) {
631 i915_gem_context_unreference(from);
636 * Clear this page out of any CPU caches for coherent swap-in/out. Note
637 * that thanks to write = false in this call and us not setting any gpu
638 * write domains when putting a context object onto the active list
639 * (when switching away from it), this won't block.
641 * XXX: We need a real interface to do this instead of trickery.
643 ret = i915_gem_object_set_to_gtt_domain(to->obj, false);
647 if (!to->obj->has_global_gtt_mapping) {
648 struct i915_vma *vma = i915_gem_obj_to_vma(to->obj,
649 &dev_priv->gtt.base);
650 vma->bind_vma(vma, to->obj->cache_level, GLOBAL_BIND);
653 if (!to->is_initialized || i915_gem_context_is_default(to))
654 hw_flags |= MI_RESTORE_INHIBIT;
656 ret = mi_set_context(ring, to, hw_flags);
660 for (i = 0; i < MAX_L3_SLICES; i++) {
661 if (!(to->remap_slice & (1<<i)))
664 ret = i915_gem_l3_remap(ring, i);
665 /* If it failed, try again next round */
667 DRM_DEBUG_DRIVER("L3 remapping failed\n");
669 to->remap_slice &= ~(1<<i);
672 /* The backing object for the context is done after switching to the
673 * *next* context. Therefore we cannot retire the previous context until
674 * the next context has already started running. In fact, the below code
675 * is a bit suboptimal because the retiring can occur simply after the
676 * MI_SET_CONTEXT instead of when the next seqno has completed.
679 from->obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
680 i915_vma_move_to_active(i915_gem_obj_to_ggtt(from->obj), ring);
681 /* As long as MI_SET_CONTEXT is serializing, ie. it flushes the
682 * whole damn pipeline, we don't need to explicitly mark the
683 * object dirty. The only exception is that the context must be
684 * correct in case the object gets swapped out. Ideally we'd be
685 * able to defer doing this until we know the object would be
686 * swapped, but there is no way to do that yet.
688 from->obj->dirty = 1;
689 BUG_ON(from->obj->ring != ring);
691 /* obj is kept alive until the next request by its active ref */
692 i915_gem_object_ggtt_unpin(from->obj);
693 i915_gem_context_unreference(from);
696 to->is_initialized = true;
699 i915_gem_context_reference(to);
700 ring->last_context = to;
701 to->last_ring = ring;
707 i915_gem_object_ggtt_unpin(to->obj);
712 * i915_switch_context() - perform a GPU context switch.
713 * @ring: ring for which we'll execute the context switch
714 * @to: the context to switch to
716 * The context life cycle is simple. The context refcount is incremented and
717 * decremented by 1 and create and destroy. If the context is in use by the GPU,
718 * it will have a refoucnt > 1. This allows us to destroy the context abstract
719 * object while letting the normal object tracking destroy the backing BO.
721 int i915_switch_context(struct intel_ring_buffer *ring,
722 struct i915_hw_context *to)
724 struct drm_i915_private *dev_priv = ring->dev->dev_private;
726 WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
728 if (to->obj == NULL) { /* We have the fake context */
729 if (to != ring->last_context) {
730 i915_gem_context_reference(to);
731 if (ring->last_context)
732 i915_gem_context_unreference(ring->last_context);
733 ring->last_context = to;
738 return do_switch(ring, to);
741 static bool hw_context_enabled(struct drm_device *dev)
743 return to_i915(dev)->hw_context_size;
746 int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
747 struct drm_file *file)
749 struct drm_i915_gem_context_create *args = data;
750 struct drm_i915_file_private *file_priv = file->driver_priv;
751 struct i915_hw_context *ctx;
754 if (!hw_context_enabled(dev))
757 ret = i915_mutex_lock_interruptible(dev);
761 ctx = i915_gem_create_context(dev, file_priv, USES_FULL_PPGTT(dev));
762 mutex_unlock(&dev->struct_mutex);
766 args->ctx_id = ctx->id;
767 DRM_DEBUG_DRIVER("HW context %d created\n", args->ctx_id);
772 int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
773 struct drm_file *file)
775 struct drm_i915_gem_context_destroy *args = data;
776 struct drm_i915_file_private *file_priv = file->driver_priv;
777 struct i915_hw_context *ctx;
780 if (args->ctx_id == DEFAULT_CONTEXT_ID)
783 ret = i915_mutex_lock_interruptible(dev);
787 ctx = i915_gem_context_get(file_priv, args->ctx_id);
789 mutex_unlock(&dev->struct_mutex);
793 idr_remove(&ctx->file_priv->context_idr, ctx->id);
794 i915_gem_context_unreference(ctx);
795 mutex_unlock(&dev->struct_mutex);
797 DRM_DEBUG_DRIVER("HW context %d destroyed\n", args->ctx_id);