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_NO_WARN)) 35 return 0; 36 37 /* 38 * If the DMA remap fails, one cause can be that we have 39 * too many objects pinned in a small remapping table, 40 * such as swiotlb. Incrementally purge all other objects and 41 * try again - if there are no more pages to remove from 42 * the DMA remapper, i915_gem_shrink will return 0. 43 */ 44 GEM_BUG_ON(obj->mm.pages == pages); 45 } while (i915_gem_shrink(to_i915(obj->base.dev), 46 obj->base.size >> PAGE_SHIFT, NULL, 47 I915_SHRINK_BOUND | 48 I915_SHRINK_UNBOUND)); 49 50 return -ENOSPC; 51 } 52 53 void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj, 54 struct sg_table *pages) 55 { 56 struct drm_i915_private *dev_priv = to_i915(obj->base.dev); 57 struct device *kdev = &dev_priv->drm.pdev->dev; 58 struct i915_ggtt *ggtt = &dev_priv->ggtt; 59 60 if (unlikely(ggtt->do_idle_maps)) { 61 /* XXX This does not prevent more requests being submitted! */ 62 if (intel_gt_retire_requests_timeout(ggtt->vm.gt, 63 -MAX_SCHEDULE_TIMEOUT)) { 64 drm_err(&dev_priv->drm, 65 "Failed to wait for idle; VT'd may hang.\n"); 66 /* Wait a bit, in hopes it avoids the hang */ 67 udelay(10); 68 } 69 } 70 71 dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL); 72 } 73 74 /** 75 * i915_gem_gtt_reserve - reserve a node in an address_space (GTT) 76 * @vm: the &struct i915_address_space 77 * @node: the &struct drm_mm_node (typically i915_vma.mode) 78 * @size: how much space to allocate inside the GTT, 79 * must be #I915_GTT_PAGE_SIZE aligned 80 * @offset: where to insert inside the GTT, 81 * must be #I915_GTT_MIN_ALIGNMENT aligned, and the node 82 * (@offset + @size) must fit within the address space 83 * @color: color to apply to node, if this node is not from a VMA, 84 * color must be #I915_COLOR_UNEVICTABLE 85 * @flags: control search and eviction behaviour 86 * 87 * i915_gem_gtt_reserve() tries to insert the @node at the exact @offset inside 88 * the address space (using @size and @color). If the @node does not fit, it 89 * tries to evict any overlapping nodes from the GTT, including any 90 * neighbouring nodes if the colors do not match (to ensure guard pages between 91 * differing domains). See i915_gem_evict_for_node() for the gory details 92 * on the eviction algorithm. #PIN_NONBLOCK may used to prevent waiting on 93 * evicting active overlapping objects, and any overlapping node that is pinned 94 * or marked as unevictable will also result in failure. 95 * 96 * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if 97 * asked to wait for eviction and interrupted. 98 */ 99 int i915_gem_gtt_reserve(struct i915_address_space *vm, 100 struct drm_mm_node *node, 101 u64 size, u64 offset, unsigned long color, 102 unsigned int flags) 103 { 104 int err; 105 106 GEM_BUG_ON(!size); 107 GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE)); 108 GEM_BUG_ON(!IS_ALIGNED(offset, I915_GTT_MIN_ALIGNMENT)); 109 GEM_BUG_ON(range_overflows(offset, size, vm->total)); 110 GEM_BUG_ON(vm == &vm->i915->ggtt.alias->vm); 111 GEM_BUG_ON(drm_mm_node_allocated(node)); 112 113 node->size = size; 114 node->start = offset; 115 node->color = color; 116 117 err = drm_mm_reserve_node(&vm->mm, node); 118 if (err != -ENOSPC) 119 return err; 120 121 if (flags & PIN_NOEVICT) 122 return -ENOSPC; 123 124 err = i915_gem_evict_for_node(vm, node, flags); 125 if (err == 0) 126 err = drm_mm_reserve_node(&vm->mm, node); 127 128 return err; 129 } 130 131 static u64 random_offset(u64 start, u64 end, u64 len, u64 align) 132 { 133 u64 range, addr; 134 135 GEM_BUG_ON(range_overflows(start, len, end)); 136 GEM_BUG_ON(round_up(start, align) > round_down(end - len, align)); 137 138 range = round_down(end - len, align) - round_up(start, align); 139 if (range) { 140 if (sizeof(unsigned long) == sizeof(u64)) { 141 addr = get_random_long(); 142 } else { 143 addr = get_random_int(); 144 if (range > U32_MAX) { 145 addr <<= 32; 146 addr |= get_random_int(); 147 } 148 } 149 div64_u64_rem(addr, range, &addr); 150 start += addr; 151 } 152 153 return round_up(start, align); 154 } 155 156 /** 157 * i915_gem_gtt_insert - insert a node into an address_space (GTT) 158 * @vm: the &struct i915_address_space 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 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 == &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, 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, 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