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 28 int 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(obj->base.dev->dev, 33 pages->sgl, pages->nents, 34 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, to_i915(obj->base.dev), 49 obj->base.size >> PAGE_SHIFT, NULL, 50 I915_SHRINK_BOUND | 51 I915_SHRINK_UNBOUND)); 52 53 return -ENOSPC; 54 } 55 56 void 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(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(100, 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 */ 97 int 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(&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(&vm->mm, node); 126 127 return err; 128 } 129 130 static 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(addr, range, &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 */ 190 int 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(&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(&vm->mm, node, 242 size, alignment, color, 243 start, end, 244 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 size, 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, size, alignment, color, 286 start, end, flags); 287 if (err) 288 return err; 289 290 return drm_mm_insert_node_in_range(&vm->mm, node, 291 size, alignment, color, 292 start, end, DRM_MM_INSERT_EVICT); 293 } 294 295 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST) 296 #include "selftests/i915_gem_gtt.c" 297 #endif 298