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1/*2 * SPDX-License-Identifier: MIT3 *4 * Copyright © 2016 Intel Corporation5 */6 7#ifndef I915_SCATTERLIST_H8#define I915_SCATTERLIST_H9 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 objects22 */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 list70 * @sg: The current sg entry71 *72 * Description:73 * If the entry is the last, return NULL; otherwise, step to the next74 * 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_table84 * @__dp: Device address (output)85 * @__iter: 'struct sgt_iter' (iterator state, internal)86 * @__sgt: sg_table to iterate over (input)87 * @__step: step size88 */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 size99 */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_table107 * @__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 scatterlist120 * @sg: The scatterlist121 *122 * Return: An unsigned int with segment sizes logically or'ed together.123 * A caller can use this information to determine what hardware page table124 * 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) address147 * space. The DMA API takes care of that both in dma_alloc_* (by148 * calling into the hypervisor to make the pages contiguous) and in149 * dma_map_* (by bounce buffering). But i915 abuses ignores the150 * coherency aspects of the DMA API and thus can't cope with bounce151 * buffering actually happening, so add a hack here to force small152 * allocations and mappings when running in PV mode on Xen.153 *154 * Note this will still break if bounce buffering is required for other155 * reasons, like confidential computing hypervisors or PCIe root ports156 * 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_sgt167 */168struct i915_refct_sgt_ops {169 /**170 * @release: Free the memory of the struct i915_refct_sgt171 */172 void (*release)(struct kref *ref);173};174 175/**176 * struct i915_refct_sgt - A refcounted scatter-gather table177 * @kref: struct kref for refcounting178 * @table: struct sg_table holding the scatter-gather table itself. Note that179 * @table->sgl = NULL can be used to determine whether a scatter-gather table180 * is present or not.181 * @size: The size in bytes of the underlying memory buffer182 * @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-table193 * @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-table203 * @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 custom214 * operations structure215 * @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-list218 * 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#endif241