1 // SPDX-License-Identifier: MIT
2 /*
3  * Copyright © 2010 Daniel Vetter
4  * Copyright © 2020 Intel Corporation
5  */
6 
7 #include <linux/slab.h> /* fault-inject.h is not standalone! */
8 
9 #include <linux/fault-inject.h>
10 #include <linux/log2.h>
11 #include <linux/random.h>
12 #include <linux/seq_file.h>
13 #include <linux/stop_machine.h>
14 
15 #include <asm/set_memory.h>
16 #include <asm/smp.h>
17 
18 #include "display/intel_frontbuffer.h"
19 #include "gt/intel_gt.h"
20 #include "gt/intel_gt_requests.h"
21 
22 #include "i915_drv.h"
23 #include "i915_scatterlist.h"
24 #include "i915_trace.h"
25 #include "i915_vgpu.h"
26 
27 int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
28 			       struct sg_table *pages)
29 {
30 	do {
31 		if (dma_map_sg_attrs(&obj->base.dev->pdev->dev,
32 				     pages->sgl, pages->nents,
33 				     PCI_DMA_BIDIRECTIONAL,
34 				     DMA_ATTR_NO_WARN))
35 			return 0;
36 
37 		/*
38 		 * If the DMA remap fails, one cause can be that we have
39 		 * too many objects pinned in a small remapping table,
40 		 * such as swiotlb. Incrementally purge all other objects and
41 		 * try again - if there are no more pages to remove from
42 		 * the DMA remapper, i915_gem_shrink will return 0.
43 		 */
44 		GEM_BUG_ON(obj->mm.pages == pages);
45 	} while (i915_gem_shrink(to_i915(obj->base.dev),
46 				 obj->base.size >> PAGE_SHIFT, NULL,
47 				 I915_SHRINK_BOUND |
48 				 I915_SHRINK_UNBOUND));
49 
50 	return -ENOSPC;
51 }
52 
53 void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
54 			       struct sg_table *pages)
55 {
56 	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
57 	struct device *kdev = &dev_priv->drm.pdev->dev;
58 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
59 
60 	if (unlikely(ggtt->do_idle_maps)) {
61 		/* XXX This does not prevent more requests being submitted! */
62 		if (intel_gt_retire_requests_timeout(ggtt->vm.gt,
63 						     -MAX_SCHEDULE_TIMEOUT)) {
64 			drm_err(&dev_priv->drm,
65 				"Failed to wait for idle; VT'd may hang.\n");
66 			/* Wait a bit, in hopes it avoids the hang */
67 			udelay(10);
68 		}
69 	}
70 
71 	dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL);
72 }
73 
74 /**
75  * i915_gem_gtt_reserve - reserve a node in an address_space (GTT)
76  * @vm: the &struct i915_address_space
77  * @node: the &struct drm_mm_node (typically i915_vma.mode)
78  * @size: how much space to allocate inside the GTT,
79  *        must be #I915_GTT_PAGE_SIZE aligned
80  * @offset: where to insert inside the GTT,
81  *          must be #I915_GTT_MIN_ALIGNMENT aligned, and the node
82  *          (@offset + @size) must fit within the address space
83  * @color: color to apply to node, if this node is not from a VMA,
84  *         color must be #I915_COLOR_UNEVICTABLE
85  * @flags: control search and eviction behaviour
86  *
87  * i915_gem_gtt_reserve() tries to insert the @node at the exact @offset inside
88  * the address space (using @size and @color). If the @node does not fit, it
89  * tries to evict any overlapping nodes from the GTT, including any
90  * neighbouring nodes if the colors do not match (to ensure guard pages between
91  * differing domains). See i915_gem_evict_for_node() for the gory details
92  * on the eviction algorithm. #PIN_NONBLOCK may used to prevent waiting on
93  * evicting active overlapping objects, and any overlapping node that is pinned
94  * or marked as unevictable will also result in failure.
95  *
96  * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
97  * asked to wait for eviction and interrupted.
98  */
99 int i915_gem_gtt_reserve(struct i915_address_space *vm,
100 			 struct drm_mm_node *node,
101 			 u64 size, u64 offset, unsigned long color,
102 			 unsigned int flags)
103 {
104 	int err;
105 
106 	GEM_BUG_ON(!size);
107 	GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
108 	GEM_BUG_ON(!IS_ALIGNED(offset, I915_GTT_MIN_ALIGNMENT));
109 	GEM_BUG_ON(range_overflows(offset, size, vm->total));
110 	GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm);
111 	GEM_BUG_ON(drm_mm_node_allocated(node));
112 
113 	node->size = size;
114 	node->start = offset;
115 	node->color = color;
116 
117 	err = drm_mm_reserve_node(&vm->mm, node);
118 	if (err != -ENOSPC)
119 		return err;
120 
121 	if (flags & PIN_NOEVICT)
122 		return -ENOSPC;
123 
124 	err = i915_gem_evict_for_node(vm, node, flags);
125 	if (err == 0)
126 		err = drm_mm_reserve_node(&vm->mm, node);
127 
128 	return err;
129 }
130 
131 static u64 random_offset(u64 start, u64 end, u64 len, u64 align)
132 {
133 	u64 range, addr;
134 
135 	GEM_BUG_ON(range_overflows(start, len, end));
136 	GEM_BUG_ON(round_up(start, align) > round_down(end - len, align));
137 
138 	range = round_down(end - len, align) - round_up(start, align);
139 	if (range) {
140 		if (sizeof(unsigned long) == sizeof(u64)) {
141 			addr = get_random_long();
142 		} else {
143 			addr = get_random_int();
144 			if (range > U32_MAX) {
145 				addr <<= 32;
146 				addr |= get_random_int();
147 			}
148 		}
149 		div64_u64_rem(addr, range, &addr);
150 		start += addr;
151 	}
152 
153 	return round_up(start, align);
154 }
155 
156 /**
157  * i915_gem_gtt_insert - insert a node into an address_space (GTT)
158  * @vm: the &struct i915_address_space
159  * @node: the &struct drm_mm_node (typically i915_vma.node)
160  * @size: how much space to allocate inside the GTT,
161  *        must be #I915_GTT_PAGE_SIZE aligned
162  * @alignment: required alignment of starting offset, may be 0 but
163  *             if specified, this must be a power-of-two and at least
164  *             #I915_GTT_MIN_ALIGNMENT
165  * @color: color to apply to node
166  * @start: start of any range restriction inside GTT (0 for all),
167  *         must be #I915_GTT_PAGE_SIZE aligned
168  * @end: end of any range restriction inside GTT (U64_MAX for all),
169  *       must be #I915_GTT_PAGE_SIZE aligned if not U64_MAX
170  * @flags: control search and eviction behaviour
171  *
172  * i915_gem_gtt_insert() first searches for an available hole into which
173  * is can insert the node. The hole address is aligned to @alignment and
174  * its @size must then fit entirely within the [@start, @end] bounds. The
175  * nodes on either side of the hole must match @color, or else a guard page
176  * will be inserted between the two nodes (or the node evicted). If no
177  * suitable hole is found, first a victim is randomly selected and tested
178  * for eviction, otherwise then the LRU list of objects within the GTT
179  * is scanned to find the first set of replacement nodes to create the hole.
180  * Those old overlapping nodes are evicted from the GTT (and so must be
181  * rebound before any future use). Any node that is currently pinned cannot
182  * be evicted (see i915_vma_pin()). Similar if the node's VMA is currently
183  * active and #PIN_NONBLOCK is specified, that node is also skipped when
184  * searching for an eviction candidate. See i915_gem_evict_something() for
185  * the gory details on the eviction algorithm.
186  *
187  * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
188  * asked to wait for eviction and interrupted.
189  */
190 int i915_gem_gtt_insert(struct i915_address_space *vm,
191 			struct drm_mm_node *node,
192 			u64 size, u64 alignment, unsigned long color,
193 			u64 start, u64 end, unsigned int flags)
194 {
195 	enum drm_mm_insert_mode mode;
196 	u64 offset;
197 	int err;
198 
199 	lockdep_assert_held(&vm->mutex);
200 
201 	GEM_BUG_ON(!size);
202 	GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
203 	GEM_BUG_ON(alignment && !is_power_of_2(alignment));
204 	GEM_BUG_ON(alignment && !IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
205 	GEM_BUG_ON(start >= end);
206 	GEM_BUG_ON(start > 0  && !IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
207 	GEM_BUG_ON(end < U64_MAX && !IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
208 	GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm);
209 	GEM_BUG_ON(drm_mm_node_allocated(node));
210 
211 	if (unlikely(range_overflows(start, size, end)))
212 		return -ENOSPC;
213 
214 	if (unlikely(round_up(start, alignment) > round_down(end - size, alignment)))
215 		return -ENOSPC;
216 
217 	mode = DRM_MM_INSERT_BEST;
218 	if (flags & PIN_HIGH)
219 		mode = DRM_MM_INSERT_HIGHEST;
220 	if (flags & PIN_MAPPABLE)
221 		mode = DRM_MM_INSERT_LOW;
222 
223 	/* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
224 	 * so we know that we always have a minimum alignment of 4096.
225 	 * The drm_mm range manager is optimised to return results
226 	 * with zero alignment, so where possible use the optimal
227 	 * path.
228 	 */
229 	BUILD_BUG_ON(I915_GTT_MIN_ALIGNMENT > I915_GTT_PAGE_SIZE);
230 	if (alignment <= I915_GTT_MIN_ALIGNMENT)
231 		alignment = 0;
232 
233 	err = drm_mm_insert_node_in_range(&vm->mm, node,
234 					  size, alignment, color,
235 					  start, end, mode);
236 	if (err != -ENOSPC)
237 		return err;
238 
239 	if (mode & DRM_MM_INSERT_ONCE) {
240 		err = drm_mm_insert_node_in_range(&vm->mm, node,
241 						  size, alignment, color,
242 						  start, end,
243 						  DRM_MM_INSERT_BEST);
244 		if (err != -ENOSPC)
245 			return err;
246 	}
247 
248 	if (flags & PIN_NOEVICT)
249 		return -ENOSPC;
250 
251 	/*
252 	 * No free space, pick a slot at random.
253 	 *
254 	 * There is a pathological case here using a GTT shared between
255 	 * mmap and GPU (i.e. ggtt/aliasing_ppgtt but not full-ppgtt):
256 	 *
257 	 *    |<-- 256 MiB aperture -->||<-- 1792 MiB unmappable -->|
258 	 *         (64k objects)             (448k objects)
259 	 *
260 	 * Now imagine that the eviction LRU is ordered top-down (just because
261 	 * pathology meets real life), and that we need to evict an object to
262 	 * make room inside the aperture. The eviction scan then has to walk
263 	 * the 448k list before it finds one within range. And now imagine that
264 	 * it has to search for a new hole between every byte inside the memcpy,
265 	 * for several simultaneous clients.
266 	 *
267 	 * On a full-ppgtt system, if we have run out of available space, there
268 	 * will be lots and lots of objects in the eviction list! Again,
269 	 * searching that LRU list may be slow if we are also applying any
270 	 * range restrictions (e.g. restriction to low 4GiB) and so, for
271 	 * simplicity and similarilty between different GTT, try the single
272 	 * random replacement first.
273 	 */
274 	offset = random_offset(start, end,
275 			       size, alignment ?: I915_GTT_MIN_ALIGNMENT);
276 	err = i915_gem_gtt_reserve(vm, node, size, offset, color, flags);
277 	if (err != -ENOSPC)
278 		return err;
279 
280 	if (flags & PIN_NOSEARCH)
281 		return -ENOSPC;
282 
283 	/* Randomly selected placement is pinned, do a search */
284 	err = i915_gem_evict_something(vm, size, alignment, color,
285 				       start, end, flags);
286 	if (err)
287 		return err;
288 
289 	return drm_mm_insert_node_in_range(&vm->mm, node,
290 					   size, alignment, color,
291 					   start, end, DRM_MM_INSERT_EVICT);
292 }
293 
294 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
295 #include "selftests/i915_gem_gtt.c"
296 #endif
297