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_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(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 
55 void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
56 			       struct sg_table *pages)
57 {
58 	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
59 	struct device *kdev = &dev_priv->drm.pdev->dev;
60 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
61 
62 	if (unlikely(ggtt->do_idle_maps)) {
63 		/* XXX This does not prevent more requests being submitted! */
64 		if (intel_gt_retire_requests_timeout(ggtt->vm.gt,
65 						     -MAX_SCHEDULE_TIMEOUT)) {
66 			drm_err(&dev_priv->drm,
67 				"Failed to wait for idle; VT'd may hang.\n");
68 			/* Wait a bit, in hopes it avoids the hang */
69 			udelay(10);
70 		}
71 	}
72 
73 	dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL);
74 }
75 
76 /**
77  * i915_gem_gtt_reserve - reserve a node in an address_space (GTT)
78  * @vm: the &struct i915_address_space
79  * @node: the &struct drm_mm_node (typically i915_vma.mode)
80  * @size: how much space to allocate inside the GTT,
81  *        must be #I915_GTT_PAGE_SIZE aligned
82  * @offset: where to insert inside the GTT,
83  *          must be #I915_GTT_MIN_ALIGNMENT aligned, and the node
84  *          (@offset + @size) must fit within the address space
85  * @color: color to apply to node, if this node is not from a VMA,
86  *         color must be #I915_COLOR_UNEVICTABLE
87  * @flags: control search and eviction behaviour
88  *
89  * i915_gem_gtt_reserve() tries to insert the @node at the exact @offset inside
90  * the address space (using @size and @color). If the @node does not fit, it
91  * tries to evict any overlapping nodes from the GTT, including any
92  * neighbouring nodes if the colors do not match (to ensure guard pages between
93  * differing domains). See i915_gem_evict_for_node() for the gory details
94  * on the eviction algorithm. #PIN_NONBLOCK may used to prevent waiting on
95  * evicting active overlapping objects, and any overlapping node that is pinned
96  * or marked as unevictable will also result in failure.
97  *
98  * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
99  * asked to wait for eviction and interrupted.
100  */
101 int i915_gem_gtt_reserve(struct i915_address_space *vm,
102 			 struct drm_mm_node *node,
103 			 u64 size, u64 offset, unsigned long color,
104 			 unsigned int flags)
105 {
106 	int err;
107 
108 	GEM_BUG_ON(!size);
109 	GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
110 	GEM_BUG_ON(!IS_ALIGNED(offset, I915_GTT_MIN_ALIGNMENT));
111 	GEM_BUG_ON(range_overflows(offset, size, vm->total));
112 	GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm);
113 	GEM_BUG_ON(drm_mm_node_allocated(node));
114 
115 	node->size = size;
116 	node->start = offset;
117 	node->color = color;
118 
119 	err = drm_mm_reserve_node(&vm->mm, node);
120 	if (err != -ENOSPC)
121 		return err;
122 
123 	if (flags & PIN_NOEVICT)
124 		return -ENOSPC;
125 
126 	err = i915_gem_evict_for_node(vm, node, flags);
127 	if (err == 0)
128 		err = drm_mm_reserve_node(&vm->mm, node);
129 
130 	return err;
131 }
132 
133 static u64 random_offset(u64 start, u64 end, u64 len, u64 align)
134 {
135 	u64 range, addr;
136 
137 	GEM_BUG_ON(range_overflows(start, len, end));
138 	GEM_BUG_ON(round_up(start, align) > round_down(end - len, align));
139 
140 	range = round_down(end - len, align) - round_up(start, align);
141 	if (range) {
142 		if (sizeof(unsigned long) == sizeof(u64)) {
143 			addr = get_random_long();
144 		} else {
145 			addr = get_random_int();
146 			if (range > U32_MAX) {
147 				addr <<= 32;
148 				addr |= get_random_int();
149 			}
150 		}
151 		div64_u64_rem(addr, range, &addr);
152 		start += addr;
153 	}
154 
155 	return round_up(start, align);
156 }
157 
158 /**
159  * i915_gem_gtt_insert - insert a node into an address_space (GTT)
160  * @vm: the &struct i915_address_space
161  * @node: the &struct drm_mm_node (typically i915_vma.node)
162  * @size: how much space to allocate inside the GTT,
163  *        must be #I915_GTT_PAGE_SIZE aligned
164  * @alignment: required alignment of starting offset, may be 0 but
165  *             if specified, this must be a power-of-two and at least
166  *             #I915_GTT_MIN_ALIGNMENT
167  * @color: color to apply to node
168  * @start: start of any range restriction inside GTT (0 for all),
169  *         must be #I915_GTT_PAGE_SIZE aligned
170  * @end: end of any range restriction inside GTT (U64_MAX for all),
171  *       must be #I915_GTT_PAGE_SIZE aligned if not U64_MAX
172  * @flags: control search and eviction behaviour
173  *
174  * i915_gem_gtt_insert() first searches for an available hole into which
175  * is can insert the node. The hole address is aligned to @alignment and
176  * its @size must then fit entirely within the [@start, @end] bounds. The
177  * nodes on either side of the hole must match @color, or else a guard page
178  * will be inserted between the two nodes (or the node evicted). If no
179  * suitable hole is found, first a victim is randomly selected and tested
180  * for eviction, otherwise then the LRU list of objects within the GTT
181  * is scanned to find the first set of replacement nodes to create the hole.
182  * Those old overlapping nodes are evicted from the GTT (and so must be
183  * rebound before any future use). Any node that is currently pinned cannot
184  * be evicted (see i915_vma_pin()). Similar if the node's VMA is currently
185  * active and #PIN_NONBLOCK is specified, that node is also skipped when
186  * searching for an eviction candidate. See i915_gem_evict_something() for
187  * the gory details on the eviction algorithm.
188  *
189  * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
190  * asked to wait for eviction and interrupted.
191  */
192 int i915_gem_gtt_insert(struct i915_address_space *vm,
193 			struct drm_mm_node *node,
194 			u64 size, u64 alignment, unsigned long color,
195 			u64 start, u64 end, unsigned int flags)
196 {
197 	enum drm_mm_insert_mode mode;
198 	u64 offset;
199 	int err;
200 
201 	lockdep_assert_held(&vm->mutex);
202 
203 	GEM_BUG_ON(!size);
204 	GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
205 	GEM_BUG_ON(alignment && !is_power_of_2(alignment));
206 	GEM_BUG_ON(alignment && !IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
207 	GEM_BUG_ON(start >= end);
208 	GEM_BUG_ON(start > 0  && !IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
209 	GEM_BUG_ON(end < U64_MAX && !IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
210 	GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm);
211 	GEM_BUG_ON(drm_mm_node_allocated(node));
212 
213 	if (unlikely(range_overflows(start, size, end)))
214 		return -ENOSPC;
215 
216 	if (unlikely(round_up(start, alignment) > round_down(end - size, alignment)))
217 		return -ENOSPC;
218 
219 	mode = DRM_MM_INSERT_BEST;
220 	if (flags & PIN_HIGH)
221 		mode = DRM_MM_INSERT_HIGHEST;
222 	if (flags & PIN_MAPPABLE)
223 		mode = DRM_MM_INSERT_LOW;
224 
225 	/* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
226 	 * so we know that we always have a minimum alignment of 4096.
227 	 * The drm_mm range manager is optimised to return results
228 	 * with zero alignment, so where possible use the optimal
229 	 * path.
230 	 */
231 	BUILD_BUG_ON(I915_GTT_MIN_ALIGNMENT > I915_GTT_PAGE_SIZE);
232 	if (alignment <= I915_GTT_MIN_ALIGNMENT)
233 		alignment = 0;
234 
235 	err = drm_mm_insert_node_in_range(&vm->mm, node,
236 					  size, alignment, color,
237 					  start, end, mode);
238 	if (err != -ENOSPC)
239 		return err;
240 
241 	if (mode & DRM_MM_INSERT_ONCE) {
242 		err = drm_mm_insert_node_in_range(&vm->mm, node,
243 						  size, alignment, color,
244 						  start, end,
245 						  DRM_MM_INSERT_BEST);
246 		if (err != -ENOSPC)
247 			return err;
248 	}
249 
250 	if (flags & PIN_NOEVICT)
251 		return -ENOSPC;
252 
253 	/*
254 	 * No free space, pick a slot at random.
255 	 *
256 	 * There is a pathological case here using a GTT shared between
257 	 * mmap and GPU (i.e. ggtt/aliasing_ppgtt but not full-ppgtt):
258 	 *
259 	 *    |<-- 256 MiB aperture -->||<-- 1792 MiB unmappable -->|
260 	 *         (64k objects)             (448k objects)
261 	 *
262 	 * Now imagine that the eviction LRU is ordered top-down (just because
263 	 * pathology meets real life), and that we need to evict an object to
264 	 * make room inside the aperture. The eviction scan then has to walk
265 	 * the 448k list before it finds one within range. And now imagine that
266 	 * it has to search for a new hole between every byte inside the memcpy,
267 	 * for several simultaneous clients.
268 	 *
269 	 * On a full-ppgtt system, if we have run out of available space, there
270 	 * will be lots and lots of objects in the eviction list! Again,
271 	 * searching that LRU list may be slow if we are also applying any
272 	 * range restrictions (e.g. restriction to low 4GiB) and so, for
273 	 * simplicity and similarilty between different GTT, try the single
274 	 * random replacement first.
275 	 */
276 	offset = random_offset(start, end,
277 			       size, alignment ?: I915_GTT_MIN_ALIGNMENT);
278 	err = i915_gem_gtt_reserve(vm, node, size, offset, color, flags);
279 	if (err != -ENOSPC)
280 		return err;
281 
282 	if (flags & PIN_NOSEARCH)
283 		return -ENOSPC;
284 
285 	/* Randomly selected placement is pinned, do a search */
286 	err = i915_gem_evict_something(vm, size, alignment, color,
287 				       start, end, flags);
288 	if (err)
289 		return err;
290 
291 	return drm_mm_insert_node_in_range(&vm->mm, node,
292 					   size, alignment, color,
293 					   start, end, DRM_MM_INSERT_EVICT);
294 }
295 
296 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
297 #include "selftests/i915_gem_gtt.c"
298 #endif
299