1 /*
2  * SPDX-License-Identifier: MIT
3  *
4  * Copyright © 2014-2016 Intel Corporation
5  */
6 
7 #include <linux/scatterlist.h>
8 #include <linux/slab.h>
9 #include <linux/swiotlb.h>
10 
11 #include "i915_drv.h"
12 #include "i915_gem.h"
13 #include "i915_gem_object.h"
14 #include "i915_scatterlist.h"
15 #include "i915_utils.h"
16 
17 #define QUIET (__GFP_NORETRY | __GFP_NOWARN)
18 #define MAYFAIL (__GFP_RETRY_MAYFAIL | __GFP_NOWARN)
19 
20 static void internal_free_pages(struct sg_table *st)
21 {
22 	struct scatterlist *sg;
23 
24 	for (sg = st->sgl; sg; sg = __sg_next(sg)) {
25 		if (sg_page(sg))
26 			__free_pages(sg_page(sg), get_order(sg->length));
27 	}
28 
29 	sg_free_table(st);
30 	kfree(st);
31 }
32 
33 static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
34 {
35 	struct drm_i915_private *i915 = to_i915(obj->base.dev);
36 	struct sg_table *st;
37 	struct scatterlist *sg;
38 	unsigned int sg_page_sizes;
39 	unsigned int npages;
40 	int max_order;
41 	gfp_t gfp;
42 
43 	max_order = MAX_ORDER;
44 #ifdef CONFIG_SWIOTLB
45 	if (is_swiotlb_active(obj->base.dev->dev)) {
46 		unsigned int max_segment;
47 
48 		max_segment = swiotlb_max_segment();
49 		if (max_segment) {
50 			max_segment = max_t(unsigned int, max_segment,
51 					    PAGE_SIZE) >> PAGE_SHIFT;
52 			max_order = min(max_order, ilog2(max_segment));
53 		}
54 	}
55 #endif
56 
57 	gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
58 	if (IS_I965GM(i915) || IS_I965G(i915)) {
59 		/* 965gm cannot relocate objects above 4GiB. */
60 		gfp &= ~__GFP_HIGHMEM;
61 		gfp |= __GFP_DMA32;
62 	}
63 
64 create_st:
65 	st = kmalloc(sizeof(*st), GFP_KERNEL);
66 	if (!st)
67 		return -ENOMEM;
68 
69 	npages = obj->base.size / PAGE_SIZE;
70 	if (sg_alloc_table(st, npages, GFP_KERNEL)) {
71 		kfree(st);
72 		return -ENOMEM;
73 	}
74 
75 	sg = st->sgl;
76 	st->nents = 0;
77 	sg_page_sizes = 0;
78 
79 	do {
80 		int order = min(fls(npages) - 1, max_order);
81 		struct page *page;
82 
83 		do {
84 			page = alloc_pages(gfp | (order ? QUIET : MAYFAIL),
85 					   order);
86 			if (page)
87 				break;
88 			if (!order--)
89 				goto err;
90 
91 			/* Limit subsequent allocations as well */
92 			max_order = order;
93 		} while (1);
94 
95 		sg_set_page(sg, page, PAGE_SIZE << order, 0);
96 		sg_page_sizes |= PAGE_SIZE << order;
97 		st->nents++;
98 
99 		npages -= 1 << order;
100 		if (!npages) {
101 			sg_mark_end(sg);
102 			break;
103 		}
104 
105 		sg = __sg_next(sg);
106 	} while (1);
107 
108 	if (i915_gem_gtt_prepare_pages(obj, st)) {
109 		/* Failed to dma-map try again with single page sg segments */
110 		if (get_order(st->sgl->length)) {
111 			internal_free_pages(st);
112 			max_order = 0;
113 			goto create_st;
114 		}
115 		goto err;
116 	}
117 
118 	__i915_gem_object_set_pages(obj, st, sg_page_sizes);
119 
120 	return 0;
121 
122 err:
123 	sg_set_page(sg, NULL, 0, 0);
124 	sg_mark_end(sg);
125 	internal_free_pages(st);
126 
127 	return -ENOMEM;
128 }
129 
130 static void i915_gem_object_put_pages_internal(struct drm_i915_gem_object *obj,
131 					       struct sg_table *pages)
132 {
133 	i915_gem_gtt_finish_pages(obj, pages);
134 	internal_free_pages(pages);
135 
136 	obj->mm.dirty = false;
137 
138 	__start_cpu_write(obj);
139 }
140 
141 static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
142 	.name = "i915_gem_object_internal",
143 	.flags = I915_GEM_OBJECT_IS_SHRINKABLE,
144 	.get_pages = i915_gem_object_get_pages_internal,
145 	.put_pages = i915_gem_object_put_pages_internal,
146 };
147 
148 /**
149  * i915_gem_object_create_internal: create an object with volatile pages
150  * @i915: the i915 device
151  * @size: the size in bytes of backing storage to allocate for the object
152  *
153  * Creates a new object that wraps some internal memory for private use.
154  * This object is not backed by swappable storage, and as such its contents
155  * are volatile and only valid whilst pinned. If the object is reaped by the
156  * shrinker, its pages and data will be discarded. Equally, it is not a full
157  * GEM object and so not valid for access from userspace. This makes it useful
158  * for hardware interfaces like ringbuffers (which are pinned from the time
159  * the request is written to the time the hardware stops accessing it), but
160  * not for contexts (which need to be preserved when not active for later
161  * reuse). Note that it is not cleared upon allocation.
162  */
163 struct drm_i915_gem_object *
164 i915_gem_object_create_internal(struct drm_i915_private *i915,
165 				phys_addr_t size)
166 {
167 	static struct lock_class_key lock_class;
168 	struct drm_i915_gem_object *obj;
169 	unsigned int cache_level;
170 
171 	GEM_BUG_ON(!size);
172 	GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
173 
174 	if (overflows_type(size, obj->base.size))
175 		return ERR_PTR(-E2BIG);
176 
177 	obj = i915_gem_object_alloc();
178 	if (!obj)
179 		return ERR_PTR(-ENOMEM);
180 
181 	drm_gem_private_object_init(&i915->drm, &obj->base, size);
182 	i915_gem_object_init(obj, &i915_gem_object_internal_ops, &lock_class, 0);
183 	obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;
184 
185 	/*
186 	 * Mark the object as volatile, such that the pages are marked as
187 	 * dontneed whilst they are still pinned. As soon as they are unpinned
188 	 * they are allowed to be reaped by the shrinker, and the caller is
189 	 * expected to repopulate - the contents of this object are only valid
190 	 * whilst active and pinned.
191 	 */
192 	i915_gem_object_set_volatile(obj);
193 
194 	obj->read_domains = I915_GEM_DOMAIN_CPU;
195 	obj->write_domain = I915_GEM_DOMAIN_CPU;
196 
197 	cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
198 	i915_gem_object_set_cache_coherency(obj, cache_level);
199 
200 	return obj;
201 }
202