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 "gt/intel_gt.h" 19 #include "gt/intel_gt_requests.h" 20 21 #include "i915_drv.h" 22 #include "i915_gem_evict.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 = to_gt(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 * @ww: An optional struct i915_gem_ww_ctx. 74 * @node: the &struct drm_mm_node (typically i915_vma.mode) 75 * @size: how much space to allocate inside the GTT, 76 * must be #I915_GTT_PAGE_SIZE aligned 77 * @offset: where to insert inside the GTT, 78 * must be #I915_GTT_MIN_ALIGNMENT aligned, and the node 79 * (@offset + @size) must fit within the address space 80 * @color: color to apply to node, if this node is not from a VMA, 81 * color must be #I915_COLOR_UNEVICTABLE 82 * @flags: control search and eviction behaviour 83 * 84 * i915_gem_gtt_reserve() tries to insert the @node at the exact @offset inside 85 * the address space (using @size and @color). If the @node does not fit, it 86 * tries to evict any overlapping nodes from the GTT, including any 87 * neighbouring nodes if the colors do not match (to ensure guard pages between 88 * differing domains). See i915_gem_evict_for_node() for the gory details 89 * on the eviction algorithm. #PIN_NONBLOCK may used to prevent waiting on 90 * evicting active overlapping objects, and any overlapping node that is pinned 91 * or marked as unevictable will also result in failure. 92 * 93 * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if 94 * asked to wait for eviction and interrupted. 95 */ 96 int i915_gem_gtt_reserve(struct i915_address_space *vm, 97 struct i915_gem_ww_ctx *ww, 98 struct drm_mm_node *node, 99 u64 size, u64 offset, unsigned long color, 100 unsigned int flags) 101 { 102 int err; 103 104 GEM_BUG_ON(!size); 105 GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE)); 106 GEM_BUG_ON(!IS_ALIGNED(offset, I915_GTT_MIN_ALIGNMENT)); 107 GEM_BUG_ON(range_overflows(offset, size, vm->total)); 108 GEM_BUG_ON(vm == &to_gt(vm->i915)->ggtt->alias->vm); 109 GEM_BUG_ON(drm_mm_node_allocated(node)); 110 111 node->size = size; 112 node->start = offset; 113 node->color = color; 114 115 err = drm_mm_reserve_node(&vm->mm, node); 116 if (err != -ENOSPC) 117 return err; 118 119 if (flags & PIN_NOEVICT) 120 return -ENOSPC; 121 122 err = i915_gem_evict_for_node(vm, ww, node, flags); 123 if (err == 0) 124 err = drm_mm_reserve_node(&vm->mm, node); 125 126 return err; 127 } 128 129 static u64 random_offset(u64 start, u64 end, u64 len, u64 align) 130 { 131 u64 range, addr; 132 133 GEM_BUG_ON(range_overflows(start, len, end)); 134 GEM_BUG_ON(round_up(start, align) > round_down(end - len, align)); 135 136 range = round_down(end - len, align) - round_up(start, align); 137 if (range) { 138 if (sizeof(unsigned long) == sizeof(u64)) { 139 addr = get_random_u64(); 140 } else { 141 addr = get_random_u32(); 142 if (range > U32_MAX) { 143 addr <<= 32; 144 addr |= get_random_u32(); 145 } 146 } 147 div64_u64_rem(addr, range, &addr); 148 start += addr; 149 } 150 151 return round_up(start, align); 152 } 153 154 /** 155 * i915_gem_gtt_insert - insert a node into an address_space (GTT) 156 * @vm: the &struct i915_address_space 157 * @ww: An optional struct i915_gem_ww_ctx. 158 * @node: the &struct drm_mm_node (typically i915_vma.node) 159 * @size: how much space to allocate inside the GTT, 160 * must be #I915_GTT_PAGE_SIZE aligned 161 * @alignment: required alignment of starting offset, may be 0 but 162 * if specified, this must be a power-of-two and at least 163 * #I915_GTT_MIN_ALIGNMENT 164 * @color: color to apply to node 165 * @start: start of any range restriction inside GTT (0 for all), 166 * must be #I915_GTT_PAGE_SIZE aligned 167 * @end: end of any range restriction inside GTT (U64_MAX for all), 168 * must be #I915_GTT_PAGE_SIZE aligned if not U64_MAX 169 * @flags: control search and eviction behaviour 170 * 171 * i915_gem_gtt_insert() first searches for an available hole into which 172 * is can insert the node. The hole address is aligned to @alignment and 173 * its @size must then fit entirely within the [@start, @end] bounds. The 174 * nodes on either side of the hole must match @color, or else a guard page 175 * will be inserted between the two nodes (or the node evicted). If no 176 * suitable hole is found, first a victim is randomly selected and tested 177 * for eviction, otherwise then the LRU list of objects within the GTT 178 * is scanned to find the first set of replacement nodes to create the hole. 179 * Those old overlapping nodes are evicted from the GTT (and so must be 180 * rebound before any future use). Any node that is currently pinned cannot 181 * be evicted (see i915_vma_pin()). Similar if the node's VMA is currently 182 * active and #PIN_NONBLOCK is specified, that node is also skipped when 183 * searching for an eviction candidate. See i915_gem_evict_something() for 184 * the gory details on the eviction algorithm. 185 * 186 * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if 187 * asked to wait for eviction and interrupted. 188 */ 189 int i915_gem_gtt_insert(struct i915_address_space *vm, 190 struct i915_gem_ww_ctx *ww, 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 == &to_gt(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, ww, 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, ww, 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