blob: fb6aa5e10991d5e1d78d3dc891751622081c0554 [file] [log] [blame]
Ben Widawsky254f9652012-06-04 14:42:42 -07001/*
2 * Copyright © 2011-2012 Intel Corporation
3 *
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:
10 *
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
13 * Software.
14 *
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
21 * IN THE SOFTWARE.
22 *
23 * Authors:
24 * Ben Widawsky <ben@bwidawsk.net>
25 *
26 */
27
28/*
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.
35 *
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.
46 *
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.
51 *
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
63 *
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
73 *
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 it's 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.
80 *
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.
85 *
86 */
87
88#include "drmP.h"
89#include "i915_drm.h"
90#include "i915_drv.h"
91
Ben Widawsky40521052012-06-04 14:42:43 -070092/* 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.
95 */
96#define CONTEXT_ALIGN (64<<10)
97
98static struct i915_hw_context *
99i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id);
100
Ben Widawsky254f9652012-06-04 14:42:42 -0700101static int get_context_size(struct drm_device *dev)
102{
103 struct drm_i915_private *dev_priv = dev->dev_private;
104 int ret;
105 u32 reg;
106
107 switch (INTEL_INFO(dev)->gen) {
108 case 6:
109 reg = I915_READ(CXT_SIZE);
110 ret = GEN6_CXT_TOTAL_SIZE(reg) * 64;
111 break;
112 case 7:
113 reg = I915_READ(GEN7_CTX_SIZE);
114 ret = GEN7_CTX_TOTAL_SIZE(reg) * 64;
115 break;
116 default:
117 BUG();
118 }
119
120 return ret;
121}
122
Ben Widawsky40521052012-06-04 14:42:43 -0700123static void do_destroy(struct i915_hw_context *ctx)
124{
125 struct drm_device *dev = ctx->obj->base.dev;
126 struct drm_i915_private *dev_priv = dev->dev_private;
127
128 if (ctx->file_priv)
129 idr_remove(&ctx->file_priv->context_idr, ctx->id);
130 else
131 BUG_ON(ctx != dev_priv->ring[RCS].default_context);
132
133 drm_gem_object_unreference(&ctx->obj->base);
134 kfree(ctx);
135}
136
137static int
138create_hw_context(struct drm_device *dev,
139 struct drm_i915_file_private *file_priv,
140 struct i915_hw_context **ctx_out)
141{
142 struct drm_i915_private *dev_priv = dev->dev_private;
143 int ret, id;
144
145 *ctx_out = kzalloc(sizeof(struct drm_i915_file_private), GFP_KERNEL);
146 if (*ctx_out == NULL)
147 return -ENOMEM;
148
149 (*ctx_out)->obj = i915_gem_alloc_object(dev,
150 dev_priv->hw_context_size);
151 if ((*ctx_out)->obj == NULL) {
152 kfree(*ctx_out);
153 DRM_DEBUG_DRIVER("Context object allocated failed\n");
154 return -ENOMEM;
155 }
156
157 /* The ring associated with the context object is handled by the normal
158 * object tracking code. We give an initial ring value simple to pass an
159 * assertion in the context switch code.
160 */
161 (*ctx_out)->ring = &dev_priv->ring[RCS];
162
163 /* Default context will never have a file_priv */
164 if (file_priv == NULL)
165 return 0;
166
167 (*ctx_out)->file_priv = file_priv;
168
169again:
170 if (idr_pre_get(&file_priv->context_idr, GFP_KERNEL) == 0) {
171 ret = -ENOMEM;
172 DRM_DEBUG_DRIVER("idr allocation failed\n");
173 goto err_out;
174 }
175
176 ret = idr_get_new_above(&file_priv->context_idr, *ctx_out,
177 DEFAULT_CONTEXT_ID + 1, &id);
178 if (ret == 0)
179 (*ctx_out)->id = id;
180
181 if (ret == -EAGAIN)
182 goto again;
183 else if (ret)
184 goto err_out;
185
186 return 0;
187
188err_out:
189 do_destroy(*ctx_out);
190 return ret;
191}
192
Ben Widawskye0556842012-06-04 14:42:46 -0700193static inline bool is_default_context(struct i915_hw_context *ctx)
194{
195 return (ctx == ctx->ring->default_context);
196}
197
Ben Widawsky254f9652012-06-04 14:42:42 -0700198/**
199 * The default context needs to exist per ring that uses contexts. It stores the
200 * context state of the GPU for applications that don't utilize HW contexts, as
201 * well as an idle case.
202 */
203static int create_default_context(struct drm_i915_private *dev_priv)
204{
Ben Widawsky40521052012-06-04 14:42:43 -0700205 struct i915_hw_context *ctx;
206 int ret;
207
208 BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
209
210 ret = create_hw_context(dev_priv->dev, NULL,
211 &dev_priv->ring[RCS].default_context);
212 if (ret)
213 return ret;
214
215 /* We may need to do things with the shrinker which require us to
216 * immediately switch back to the default context. This can cause a
217 * problem as pinning the default context also requires GTT space which
218 * may not be available. To avoid this we always pin the
219 * default context.
220 */
221 ctx = dev_priv->ring[RCS].default_context;
222 ret = i915_gem_object_pin(ctx->obj, CONTEXT_ALIGN, false);
223 if (ret) {
224 do_destroy(ctx);
225 return ret;
226 }
227
228 return ret;
Ben Widawsky254f9652012-06-04 14:42:42 -0700229}
230
231void i915_gem_context_init(struct drm_device *dev)
232{
233 struct drm_i915_private *dev_priv = dev->dev_private;
234 uint32_t ctx_size;
235
236 if (!HAS_HW_CONTEXTS(dev))
237 return;
238
239 /* If called from reset, or thaw... we've been here already */
Ben Widawsky40521052012-06-04 14:42:43 -0700240 if (dev_priv->hw_contexts_disabled ||
241 dev_priv->ring[RCS].default_context)
Ben Widawsky254f9652012-06-04 14:42:42 -0700242 return;
243
244 ctx_size = get_context_size(dev);
245 dev_priv->hw_context_size = get_context_size(dev);
246 dev_priv->hw_context_size = round_up(dev_priv->hw_context_size, 4096);
247
248 if (ctx_size <= 0 || ctx_size > (1<<20)) {
249 dev_priv->hw_contexts_disabled = true;
250 return;
251 }
252
253 if (create_default_context(dev_priv)) {
254 dev_priv->hw_contexts_disabled = true;
255 return;
256 }
257
258 DRM_DEBUG_DRIVER("HW context support initialized\n");
259}
260
261void i915_gem_context_fini(struct drm_device *dev)
262{
263 struct drm_i915_private *dev_priv = dev->dev_private;
264
265 if (dev_priv->hw_contexts_disabled)
266 return;
Ben Widawsky40521052012-06-04 14:42:43 -0700267
268 i915_gem_object_unpin(dev_priv->ring[RCS].default_context->obj);
269
270 do_destroy(dev_priv->ring[RCS].default_context);
Ben Widawsky254f9652012-06-04 14:42:42 -0700271}
272
273void i915_gem_context_open(struct drm_device *dev, struct drm_file *file)
274{
275 struct drm_i915_private *dev_priv = dev->dev_private;
Ben Widawsky40521052012-06-04 14:42:43 -0700276 struct drm_i915_file_private *file_priv = file->driver_priv;
Ben Widawsky254f9652012-06-04 14:42:42 -0700277
278 if (dev_priv->hw_contexts_disabled)
279 return;
Ben Widawsky40521052012-06-04 14:42:43 -0700280
281 idr_init(&file_priv->context_idr);
282}
283
284static int context_idr_cleanup(int id, void *p, void *data)
285{
286 struct drm_file *file = (struct drm_file *)data;
287 struct drm_i915_file_private *file_priv = file->driver_priv;
288 struct i915_hw_context *ctx;
289
290 BUG_ON(id == DEFAULT_CONTEXT_ID);
291 ctx = i915_gem_context_get(file_priv, id);
292 if (WARN_ON(ctx == NULL))
293 return -ENXIO;
294
295 do_destroy(ctx);
296
297 return 0;
Ben Widawsky254f9652012-06-04 14:42:42 -0700298}
299
300void i915_gem_context_close(struct drm_device *dev, struct drm_file *file)
301{
302 struct drm_i915_private *dev_priv = dev->dev_private;
Ben Widawsky40521052012-06-04 14:42:43 -0700303 struct drm_i915_file_private *file_priv = file->driver_priv;
Ben Widawsky254f9652012-06-04 14:42:42 -0700304
305 if (dev_priv->hw_contexts_disabled)
306 return;
Ben Widawsky40521052012-06-04 14:42:43 -0700307
308 mutex_lock(&dev->struct_mutex);
309 idr_for_each(&file_priv->context_idr, context_idr_cleanup, file);
310 idr_destroy(&file_priv->context_idr);
311 mutex_unlock(&dev->struct_mutex);
312}
313
Ben Widawskye0556842012-06-04 14:42:46 -0700314static struct i915_hw_context *
Ben Widawsky40521052012-06-04 14:42:43 -0700315i915_gem_context_get(struct drm_i915_file_private *file_priv, u32 id)
316{
317 return (struct i915_hw_context *)idr_find(&file_priv->context_idr, id);
Ben Widawsky254f9652012-06-04 14:42:42 -0700318}
Ben Widawskye0556842012-06-04 14:42:46 -0700319
320static inline int
321mi_set_context(struct intel_ring_buffer *ring,
322 struct i915_hw_context *new_context,
323 u32 hw_flags)
324{
325 int ret;
326
327 ret = intel_ring_begin(ring, 4);
328 if (ret)
329 return ret;
330
331 intel_ring_emit(ring, MI_NOOP);
332 intel_ring_emit(ring, MI_SET_CONTEXT);
333 intel_ring_emit(ring, new_context->obj->gtt_offset |
334 MI_MM_SPACE_GTT |
335 MI_SAVE_EXT_STATE_EN |
336 MI_RESTORE_EXT_STATE_EN |
337 hw_flags);
338 /* w/a: MI_SET_CONTEXT must always be followed by MI_NOOP */
339 intel_ring_emit(ring, MI_NOOP);
340
341 intel_ring_advance(ring);
342
343 return ret;
344}
345
346static int do_switch(struct drm_i915_gem_object *from_obj,
347 struct i915_hw_context *to,
348 u32 seqno)
349{
350 struct intel_ring_buffer *ring = NULL;
351 u32 hw_flags = 0;
352 int ret;
353
354 BUG_ON(to == NULL);
355 BUG_ON(from_obj != NULL && from_obj->pin_count == 0);
356
357 ret = i915_gem_object_pin(to->obj, CONTEXT_ALIGN, false);
358 if (ret)
359 return ret;
360
Daniel Vetter3af7b852012-06-14 00:08:32 +0200361 if (!to->obj->has_global_gtt_mapping)
362 i915_gem_gtt_bind_object(to->obj, to->obj->cache_level);
363
Ben Widawskye0556842012-06-04 14:42:46 -0700364 if (!to->is_initialized || is_default_context(to))
365 hw_flags |= MI_RESTORE_INHIBIT;
366 else if (WARN_ON_ONCE(from_obj == to->obj)) /* not yet expected */
367 hw_flags |= MI_FORCE_RESTORE;
368
369 ring = to->ring;
370 ret = mi_set_context(ring, to, hw_flags);
371 if (ret) {
372 i915_gem_object_unpin(to->obj);
373 return ret;
374 }
375
376 /* The backing object for the context is done after switching to the
377 * *next* context. Therefore we cannot retire the previous context until
378 * the next context has already started running. In fact, the below code
379 * is a bit suboptimal because the retiring can occur simply after the
380 * MI_SET_CONTEXT instead of when the next seqno has completed.
381 */
382 if (from_obj != NULL) {
383 from_obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
384 i915_gem_object_move_to_active(from_obj, ring, seqno);
385 /* As long as MI_SET_CONTEXT is serializing, ie. it flushes the
386 * whole damn pipeline, we don't need to explicitly mark the
387 * object dirty. The only exception is that the context must be
388 * correct in case the object gets swapped out. Ideally we'd be
389 * able to defer doing this until we know the object would be
390 * swapped, but there is no way to do that yet.
391 */
392 from_obj->dirty = 1;
393 BUG_ON(from_obj->ring != to->ring);
394 i915_gem_object_unpin(from_obj);
395 }
396
397 ring->last_context_obj = to->obj;
398 to->is_initialized = true;
399
400 return 0;
401}
402
403/**
404 * i915_switch_context() - perform a GPU context switch.
405 * @ring: ring for which we'll execute the context switch
406 * @file_priv: file_priv associated with the context, may be NULL
407 * @id: context id number
408 * @seqno: sequence number by which the new context will be switched to
409 * @flags:
410 *
411 * The context life cycle is simple. The context refcount is incremented and
412 * decremented by 1 and create and destroy. If the context is in use by the GPU,
413 * it will have a refoucnt > 1. This allows us to destroy the context abstract
414 * object while letting the normal object tracking destroy the backing BO.
415 */
416int i915_switch_context(struct intel_ring_buffer *ring,
417 struct drm_file *file,
418 int to_id)
419{
420 struct drm_i915_private *dev_priv = ring->dev->dev_private;
421 struct drm_i915_file_private *file_priv = NULL;
422 struct i915_hw_context *to;
423 struct drm_i915_gem_object *from_obj = ring->last_context_obj;
424 int ret;
425
426 if (dev_priv->hw_contexts_disabled)
427 return 0;
428
429 if (ring != &dev_priv->ring[RCS])
430 return 0;
431
432 if (file)
433 file_priv = file->driver_priv;
434
435 if (to_id == DEFAULT_CONTEXT_ID) {
436 to = ring->default_context;
437 } else {
438 to = i915_gem_context_get(file_priv, to_id);
439 if (to == NULL)
440 return -EINVAL;
441 }
442
443 if (from_obj == to->obj)
444 return 0;
445
446 ret = do_switch(from_obj, to, i915_gem_next_request_seqno(to->ring));
447 if (ret)
448 return ret;
449
450 /* Just to make the code a little cleaner we take the object reference
451 * after the switch was successful. It would be more intuitive to ref
452 * the 'to' object before the switch but we know the refcount must be >0
453 * if context_get() succeeded, and we hold struct mutex. So it's safe to
454 * do this here/now
455 */
456 drm_gem_object_reference(&to->obj->base);
457 if (from_obj != NULL)
458 drm_gem_object_unreference(&from_obj->base);
459 return ret;
460}