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 17struct drm_mm_node; 18struct ttm_resource; 19 20/* 21 * Optimised SGL iterator for GEM objects 22 */ 23static __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 50static inline int __sg_page_count(const struct scatterlist *sg) 51{ 52 return sg->length >> PAGE_SHIFT; 53} 54 55static inline int __sg_dma_page_count(const struct scatterlist *sg) 56{ 57 return sg_dma_len(sg) >> PAGE_SHIFT; 58} 59 60static 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 **/ 77static 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 * __for_each_daddr_next - iterates over the device addresses with pre-initialized iterator. 96 * @__dp: Device address (output) 97 * @__iter: 'struct sgt_iter' (iterator state, external) 98 * @__step: step size 99 */ 100#define __for_each_daddr_next(__dp, __iter, __step) \ 101 for (; ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \ 102 (((__iter).curr += (__step)) >= (__iter).max) ? \ 103 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0) 104 105/** 106 * for_each_sgt_page - iterate over the pages of the given sg_table 107 * @__pp: page pointer (output) 108 * @__iter: 'struct sgt_iter' (iterator state, internal) 109 * @__sgt: sg_table to iterate over (input) 110 */ 111#define for_each_sgt_page(__pp, __iter, __sgt) \ 112 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \ 113 ((__pp) = (__iter).pfn == 0 ? NULL : \ 114 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \ 115 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \ 116 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0) 117 118/** 119 * i915_sg_dma_sizes - Record the dma segment sizes of a scatterlist 120 * @sg: The scatterlist 121 * 122 * Return: An unsigned int with segment sizes logically or'ed together. 123 * A caller can use this information to determine what hardware page table 124 * entry sizes can be used to map the memory represented by the scatterlist. 125 */ 126static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg) 127{ 128 unsigned int page_sizes; 129 130 page_sizes = 0; 131 while (sg && sg_dma_len(sg)) { 132 GEM_BUG_ON(sg->offset); 133 GEM_BUG_ON(!IS_ALIGNED(sg_dma_len(sg), PAGE_SIZE)); 134 page_sizes |= sg_dma_len(sg); 135 sg = __sg_next(sg); 136 } 137 138 return page_sizes; 139} 140 141static inline unsigned int i915_sg_segment_size(struct device *dev) 142{ 143 size_t max = min_t(size_t, UINT_MAX, dma_max_mapping_size(dev)); 144 145 /* 146 * For Xen PV guests pages aren't contiguous in DMA (machine) address 147 * space. The DMA API takes care of that both in dma_alloc_* (by 148 * calling into the hypervisor to make the pages contiguous) and in 149 * dma_map_* (by bounce buffering). But i915 abuses ignores the 150 * coherency aspects of the DMA API and thus can't cope with bounce 151 * buffering actually happening, so add a hack here to force small 152 * allocations and mappings when running in PV mode on Xen. 153 * 154 * Note this will still break if bounce buffering is required for other 155 * reasons, like confidential computing hypervisors or PCIe root ports 156 * with addressing limitations. 157 */ 158 if (xen_pv_domain()) 159 max = PAGE_SIZE; 160 return round_down(max, PAGE_SIZE); 161} 162 163bool i915_sg_trim(struct sg_table *orig_st); 164 165/** 166 * struct i915_refct_sgt_ops - Operations structure for struct i915_refct_sgt 167 */ 168struct i915_refct_sgt_ops { 169 /** 170 * @release: Free the memory of the struct i915_refct_sgt 171 */ 172 void (*release)(struct kref *ref); 173}; 174 175/** 176 * struct i915_refct_sgt - A refcounted scatter-gather table 177 * @kref: struct kref for refcounting 178 * @table: struct sg_table holding the scatter-gather table itself. Note that 179 * @table->sgl = NULL can be used to determine whether a scatter-gather table 180 * is present or not. 181 * @size: The size in bytes of the underlying memory buffer 182 * @ops: The operations structure. 183 */ 184struct i915_refct_sgt { 185 struct kref kref; 186 struct sg_table table; 187 size_t size; 188 const struct i915_refct_sgt_ops *ops; 189}; 190 191/** 192 * i915_refct_sgt_put - Put a refcounted sg-table 193 * @rsgt: the struct i915_refct_sgt to put. 194 */ 195static inline void i915_refct_sgt_put(struct i915_refct_sgt *rsgt) 196{ 197 if (rsgt) 198 kref_put(&rsgt->kref, rsgt->ops->release); 199} 200 201/** 202 * i915_refct_sgt_get - Get a refcounted sg-table 203 * @rsgt: the struct i915_refct_sgt to get. 204 */ 205static inline struct i915_refct_sgt * 206i915_refct_sgt_get(struct i915_refct_sgt *rsgt) 207{ 208 kref_get(&rsgt->kref); 209 return rsgt; 210} 211 212/** 213 * __i915_refct_sgt_init - Initialize a refcounted sg-list with a custom 214 * operations structure 215 * @rsgt: The struct i915_refct_sgt to initialize. 216 * @size: Size in bytes of the underlying memory buffer. 217 * @ops: A customized operations structure in case the refcounted sg-list 218 * is embedded into another structure. 219 */ 220static inline void __i915_refct_sgt_init(struct i915_refct_sgt *rsgt, 221 size_t size, 222 const struct i915_refct_sgt_ops *ops) 223{ 224 kref_init(&rsgt->kref); 225 rsgt->table.sgl = NULL; 226 rsgt->size = size; 227 rsgt->ops = ops; 228} 229 230void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size); 231 232struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node, 233 u64 region_start, 234 u32 page_alignment); 235 236struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res, 237 u64 region_start, 238 u32 page_alignment); 239 240#endif 241