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