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_gem_evict.h"
24#include "i915_scatterlist.h"
25#include "i915_trace.h"
26#include "i915_vgpu.h"
27
28int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
29 struct sg_table *pages)
30{
31 do {
32 if (dma_map_sg_attrs(dev: obj->base.dev->dev,
33 sg: pages->sgl, nents: pages->nents,
34 dir: DMA_BIDIRECTIONAL,
35 DMA_ATTR_SKIP_CPU_SYNC |
36 DMA_ATTR_NO_KERNEL_MAPPING |
37 DMA_ATTR_NO_WARN))
38 return 0;
39
40 /*
41 * If the DMA remap fails, one cause can be that we have
42 * too many objects pinned in a small remapping table,
43 * such as swiotlb. Incrementally purge all other objects and
44 * try again - if there are no more pages to remove from
45 * the DMA remapper, i915_gem_shrink will return 0.
46 */
47 GEM_BUG_ON(obj->mm.pages == pages);
48 } while (i915_gem_shrink(NULL, i915: to_i915(dev: obj->base.dev),
49 target: obj->base.size >> PAGE_SHIFT, NULL,
50 I915_SHRINK_BOUND |
51 I915_SHRINK_UNBOUND));
52
53 return -ENOSPC;
54}
55
56void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
57 struct sg_table *pages)
58{
59 struct drm_i915_private *i915 = to_i915(dev: obj->base.dev);
60 struct i915_ggtt *ggtt = to_gt(i915)->ggtt;
61
62 /* XXX This does not prevent more requests being submitted! */
63 if (unlikely(ggtt->do_idle_maps))
64 /* Wait a bit, in the hope it avoids the hang */
65 usleep_range(min: 100, max: 250);
66
67 dma_unmap_sg(i915->drm.dev, pages->sgl, pages->nents,
68 DMA_BIDIRECTIONAL);
69}
70
71/**
72 * i915_gem_gtt_reserve - reserve a node in an address_space (GTT)
73 * @vm: the &struct i915_address_space
74 * @ww: An optional struct i915_gem_ww_ctx.
75 * @node: the &struct drm_mm_node (typically i915_vma.mode)
76 * @size: how much space to allocate inside the GTT,
77 * must be #I915_GTT_PAGE_SIZE aligned
78 * @offset: where to insert inside the GTT,
79 * must be #I915_GTT_MIN_ALIGNMENT aligned, and the node
80 * (@offset + @size) must fit within the address space
81 * @color: color to apply to node, if this node is not from a VMA,
82 * color must be #I915_COLOR_UNEVICTABLE
83 * @flags: control search and eviction behaviour
84 *
85 * i915_gem_gtt_reserve() tries to insert the @node at the exact @offset inside
86 * the address space (using @size and @color). If the @node does not fit, it
87 * tries to evict any overlapping nodes from the GTT, including any
88 * neighbouring nodes if the colors do not match (to ensure guard pages between
89 * differing domains). See i915_gem_evict_for_node() for the gory details
90 * on the eviction algorithm. #PIN_NONBLOCK may used to prevent waiting on
91 * evicting active overlapping objects, and any overlapping node that is pinned
92 * or marked as unevictable will also result in failure.
93 *
94 * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
95 * asked to wait for eviction and interrupted.
96 */
97int i915_gem_gtt_reserve(struct i915_address_space *vm,
98 struct i915_gem_ww_ctx *ww,
99 struct drm_mm_node *node,
100 u64 size, u64 offset, unsigned long color,
101 unsigned int flags)
102{
103 int err;
104
105 GEM_BUG_ON(!size);
106 GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
107 GEM_BUG_ON(!IS_ALIGNED(offset, I915_GTT_MIN_ALIGNMENT));
108 GEM_BUG_ON(range_overflows(offset, size, vm->total));
109 GEM_BUG_ON(vm == &to_gt(vm->i915)->ggtt->alias->vm);
110 GEM_BUG_ON(drm_mm_node_allocated(node));
111
112 node->size = size;
113 node->start = offset;
114 node->color = color;
115
116 err = drm_mm_reserve_node(mm: &vm->mm, node);
117 if (err != -ENOSPC)
118 return err;
119
120 if (flags & PIN_NOEVICT)
121 return -ENOSPC;
122
123 err = i915_gem_evict_for_node(vm, ww, node, flags);
124 if (err == 0)
125 err = drm_mm_reserve_node(mm: &vm->mm, node);
126
127 return err;
128}
129
130static u64 random_offset(u64 start, u64 end, u64 len, u64 align)
131{
132 u64 range, addr;
133
134 GEM_BUG_ON(range_overflows(start, len, end));
135 GEM_BUG_ON(round_up(start, align) > round_down(end - len, align));
136
137 range = round_down(end - len, align) - round_up(start, align);
138 if (range) {
139 if (sizeof(unsigned long) == sizeof(u64)) {
140 addr = get_random_u64();
141 } else {
142 addr = get_random_u32();
143 if (range > U32_MAX) {
144 addr <<= 32;
145 addr |= get_random_u32();
146 }
147 }
148 div64_u64_rem(dividend: addr, divisor: range, remainder: &addr);
149 start += addr;
150 }
151
152 return round_up(start, align);
153}
154
155/**
156 * i915_gem_gtt_insert - insert a node into an address_space (GTT)
157 * @vm: the &struct i915_address_space
158 * @ww: An optional struct i915_gem_ww_ctx.
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 */
190int i915_gem_gtt_insert(struct i915_address_space *vm,
191 struct i915_gem_ww_ctx *ww,
192 struct drm_mm_node *node,
193 u64 size, u64 alignment, unsigned long color,
194 u64 start, u64 end, unsigned int flags)
195{
196 enum drm_mm_insert_mode mode;
197 u64 offset;
198 int err;
199
200 lockdep_assert_held(&vm->mutex);
201
202 GEM_BUG_ON(!size);
203 GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
204 GEM_BUG_ON(alignment && !is_power_of_2(alignment));
205 GEM_BUG_ON(alignment && !IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
206 GEM_BUG_ON(start >= end);
207 GEM_BUG_ON(start > 0 && !IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
208 GEM_BUG_ON(end < U64_MAX && !IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
209 GEM_BUG_ON(vm == &to_gt(vm->i915)->ggtt->alias->vm);
210 GEM_BUG_ON(drm_mm_node_allocated(node));
211
212 if (unlikely(range_overflows(start, size, end)))
213 return -ENOSPC;
214
215 if (unlikely(round_up(start, alignment) > round_down(end - size, alignment)))
216 return -ENOSPC;
217
218 mode = DRM_MM_INSERT_BEST;
219 if (flags & PIN_HIGH)
220 mode = DRM_MM_INSERT_HIGHEST;
221 if (flags & PIN_MAPPABLE)
222 mode = DRM_MM_INSERT_LOW;
223
224 /* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
225 * so we know that we always have a minimum alignment of 4096.
226 * The drm_mm range manager is optimised to return results
227 * with zero alignment, so where possible use the optimal
228 * path.
229 */
230 BUILD_BUG_ON(I915_GTT_MIN_ALIGNMENT > I915_GTT_PAGE_SIZE);
231 if (alignment <= I915_GTT_MIN_ALIGNMENT)
232 alignment = 0;
233
234 err = drm_mm_insert_node_in_range(mm: &vm->mm, node,
235 size, alignment, color,
236 start, end, mode);
237 if (err != -ENOSPC)
238 return err;
239
240 if (mode & DRM_MM_INSERT_ONCE) {
241 err = drm_mm_insert_node_in_range(mm: &vm->mm, node,
242 size, alignment, color,
243 start, end,
244 mode: DRM_MM_INSERT_BEST);
245 if (err != -ENOSPC)
246 return err;
247 }
248
249 if (flags & PIN_NOEVICT)
250 return -ENOSPC;
251
252 /*
253 * No free space, pick a slot at random.
254 *
255 * There is a pathological case here using a GTT shared between
256 * mmap and GPU (i.e. ggtt/aliasing_ppgtt but not full-ppgtt):
257 *
258 * |<-- 256 MiB aperture -->||<-- 1792 MiB unmappable -->|
259 * (64k objects) (448k objects)
260 *
261 * Now imagine that the eviction LRU is ordered top-down (just because
262 * pathology meets real life), and that we need to evict an object to
263 * make room inside the aperture. The eviction scan then has to walk
264 * the 448k list before it finds one within range. And now imagine that
265 * it has to search for a new hole between every byte inside the memcpy,
266 * for several simultaneous clients.
267 *
268 * On a full-ppgtt system, if we have run out of available space, there
269 * will be lots and lots of objects in the eviction list! Again,
270 * searching that LRU list may be slow if we are also applying any
271 * range restrictions (e.g. restriction to low 4GiB) and so, for
272 * simplicity and similarilty between different GTT, try the single
273 * random replacement first.
274 */
275 offset = random_offset(start, end,
276 len: size, align: alignment ?: I915_GTT_MIN_ALIGNMENT);
277 err = i915_gem_gtt_reserve(vm, ww, node, size, offset, color, flags);
278 if (err != -ENOSPC)
279 return err;
280
281 if (flags & PIN_NOSEARCH)
282 return -ENOSPC;
283
284 /* Randomly selected placement is pinned, do a search */
285 err = i915_gem_evict_something(vm, ww, min_size: size, alignment, color,
286 start, end, flags);
287 if (err)
288 return err;
289
290 return drm_mm_insert_node_in_range(mm: &vm->mm, node,
291 size, alignment, color,
292 start, end, mode: DRM_MM_INSERT_EVICT);
293}
294
295#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
296#include "selftests/i915_gem_gtt.c"
297#endif
298

source code of linux/drivers/gpu/drm/i915/i915_gem_gtt.c