1 /* 2 * SPDX-License-Identifier: MIT 3 * 4 * Copyright © 2016 Intel Corporation 5 */ 6 7 #ifndef I915_SCATTERLIST_H 8 #define I915_SCATTERLIST_H 9 10 #include <linux/pfn.h> 11 #include <linux/scatterlist.h> 12 #include <linux/dma-mapping.h> 13 #include <xen/xen.h> 14 15 #include "i915_gem.h" 16 17 struct drm_mm_node; 18 struct ttm_resource; 19 20 /* 21 * Optimised SGL iterator for GEM objects 22 */ 23 static __always_inline struct sgt_iter { 24 struct scatterlist *sgp; 25 union { 26 unsigned long pfn; 27 dma_addr_t dma; 28 }; 29 unsigned int curr; 30 unsigned int max; 31 } __sgt_iter(struct scatterlist *sgl, bool dma) { 32 struct sgt_iter s = { .sgp = sgl }; 33 34 if (dma && s.sgp && sg_dma_len(s.sgp) == 0) { 35 s.sgp = NULL; 36 } else if (s.sgp) { 37 s.max = s.curr = s.sgp->offset; 38 if (dma) { 39 s.dma = sg_dma_address(s.sgp); 40 s.max += sg_dma_len(s.sgp); 41 } else { 42 s.pfn = page_to_pfn(sg_page(s.sgp)); 43 s.max += s.sgp->length; 44 } 45 } 46 47 return s; 48 } 49 50 static inline int __sg_page_count(const struct scatterlist *sg) 51 { 52 return sg->length >> PAGE_SHIFT; 53 } 54 55 static inline int __sg_dma_page_count(const struct scatterlist *sg) 56 { 57 return sg_dma_len(sg) >> PAGE_SHIFT; 58 } 59 60 static inline struct scatterlist *____sg_next(struct scatterlist *sg) 61 { 62 ++sg; 63 if (unlikely(sg_is_chain(sg))) 64 sg = sg_chain_ptr(sg); 65 return sg; 66 } 67 68 /** 69 * __sg_next - return the next scatterlist entry in a list 70 * @sg: The current sg entry 71 * 72 * Description: 73 * If the entry is the last, return NULL; otherwise, step to the next 74 * element in the array (@sg@+1). If that's a chain pointer, follow it; 75 * otherwise just return the pointer to the current element. 76 **/ 77 static inline struct scatterlist *__sg_next(struct scatterlist *sg) 78 { 79 return sg_is_last(sg) ? NULL : ____sg_next(sg); 80 } 81 82 /** 83 * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table 84 * @__dp: Device address (output) 85 * @__iter: 'struct sgt_iter' (iterator state, internal) 86 * @__sgt: sg_table to iterate over (input) 87 * @__step: step size 88 */ 89 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step) \ 90 for ((__iter) = __sgt_iter((__sgt)->sgl, true); \ 91 ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \ 92 (((__iter).curr += (__step)) >= (__iter).max) ? \ 93 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0) 94 95 /** 96 * for_each_sgt_page - iterate over the pages of the given sg_table 97 * @__pp: page pointer (output) 98 * @__iter: 'struct sgt_iter' (iterator state, internal) 99 * @__sgt: sg_table to iterate over (input) 100 */ 101 #define for_each_sgt_page(__pp, __iter, __sgt) \ 102 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \ 103 ((__pp) = (__iter).pfn == 0 ? NULL : \ 104 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \ 105 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \ 106 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0) 107 108 /** 109 * i915_sg_dma_sizes - Record the dma segment sizes of a scatterlist 110 * @sg: The scatterlist 111 * 112 * Return: An unsigned int with segment sizes logically or'ed together. 113 * A caller can use this information to determine what hardware page table 114 * entry sizes can be used to map the memory represented by the scatterlist. 115 */ 116 static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg) 117 { 118 unsigned int page_sizes; 119 120 page_sizes = 0; 121 while (sg && sg_dma_len(sg)) { 122 GEM_BUG_ON(sg->offset); 123 GEM_BUG_ON(!IS_ALIGNED(sg_dma_len(sg), PAGE_SIZE)); 124 page_sizes |= sg_dma_len(sg); 125 sg = __sg_next(sg); 126 } 127 128 return page_sizes; 129 } 130 131 static inline unsigned int i915_sg_segment_size(struct device *dev) 132 { 133 size_t max = min_t(size_t, UINT_MAX, dma_max_mapping_size(dev)); 134 135 /* 136 * For Xen PV guests pages aren't contiguous in DMA (machine) address 137 * space. The DMA API takes care of that both in dma_alloc_* (by 138 * calling into the hypervisor to make the pages contiguous) and in 139 * dma_map_* (by bounce buffering). But i915 abuses ignores the 140 * coherency aspects of the DMA API and thus can't cope with bounce 141 * buffering actually happening, so add a hack here to force small 142 * allocations and mappings when running in PV mode on Xen. 143 * 144 * Note this will still break if bounce buffering is required for other 145 * reasons, like confidential computing hypervisors or PCIe root ports 146 * with addressing limitations. 147 */ 148 if (xen_pv_domain()) 149 max = PAGE_SIZE; 150 return round_down(max, PAGE_SIZE); 151 } 152 153 bool i915_sg_trim(struct sg_table *orig_st); 154 155 /** 156 * struct i915_refct_sgt_ops - Operations structure for struct i915_refct_sgt 157 */ 158 struct i915_refct_sgt_ops { 159 /** 160 * @release: Free the memory of the struct i915_refct_sgt 161 */ 162 void (*release)(struct kref *ref); 163 }; 164 165 /** 166 * struct i915_refct_sgt - A refcounted scatter-gather table 167 * @kref: struct kref for refcounting 168 * @table: struct sg_table holding the scatter-gather table itself. Note that 169 * @table->sgl = NULL can be used to determine whether a scatter-gather table 170 * is present or not. 171 * @size: The size in bytes of the underlying memory buffer 172 * @ops: The operations structure. 173 */ 174 struct i915_refct_sgt { 175 struct kref kref; 176 struct sg_table table; 177 size_t size; 178 const struct i915_refct_sgt_ops *ops; 179 }; 180 181 /** 182 * i915_refct_sgt_put - Put a refcounted sg-table 183 * @rsgt: the struct i915_refct_sgt to put. 184 */ 185 static inline void i915_refct_sgt_put(struct i915_refct_sgt *rsgt) 186 { 187 if (rsgt) 188 kref_put(&rsgt->kref, rsgt->ops->release); 189 } 190 191 /** 192 * i915_refct_sgt_get - Get a refcounted sg-table 193 * @rsgt: the struct i915_refct_sgt to get. 194 */ 195 static inline struct i915_refct_sgt * 196 i915_refct_sgt_get(struct i915_refct_sgt *rsgt) 197 { 198 kref_get(&rsgt->kref); 199 return rsgt; 200 } 201 202 /** 203 * __i915_refct_sgt_init - Initialize a refcounted sg-list with a custom 204 * operations structure 205 * @rsgt: The struct i915_refct_sgt to initialize. 206 * @size: Size in bytes of the underlying memory buffer. 207 * @ops: A customized operations structure in case the refcounted sg-list 208 * is embedded into another structure. 209 */ 210 static inline void __i915_refct_sgt_init(struct i915_refct_sgt *rsgt, 211 size_t size, 212 const struct i915_refct_sgt_ops *ops) 213 { 214 kref_init(&rsgt->kref); 215 rsgt->table.sgl = NULL; 216 rsgt->size = size; 217 rsgt->ops = ops; 218 } 219 220 void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size); 221 222 struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node, 223 u64 region_start, 224 u32 page_alignment); 225 226 struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res, 227 u64 region_start, 228 u32 page_alignment); 229 230 #endif 231