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(kref: &rsgt->kref, release: 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(kref: &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(kref: &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