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->dev, 32 pages->sgl, pages->nents, 33 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 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 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 */ 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 } 126 127 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 */ 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