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
 20static 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
 33static 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 (swiotlb_nr_tbl()) {
 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
 64create_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
122err:
123	sg_set_page(sg, NULL, 0, 0);
124	sg_mark_end(sg);
125	internal_free_pages(st);
126
127	return -ENOMEM;
128}
129
130static 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
139static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
140	.name = "i915_gem_object_internal",
141	.flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE |
142		 I915_GEM_OBJECT_IS_SHRINKABLE,
143	.get_pages = i915_gem_object_get_pages_internal,
144	.put_pages = i915_gem_object_put_pages_internal,
145};
146
147/**
148 * i915_gem_object_create_internal: create an object with volatile pages
149 * @i915: the i915 device
150 * @size: the size in bytes of backing storage to allocate for the object
151 *
152 * Creates a new object that wraps some internal memory for private use.
153 * This object is not backed by swappable storage, and as such its contents
154 * are volatile and only valid whilst pinned. If the object is reaped by the
155 * shrinker, its pages and data will be discarded. Equally, it is not a full
156 * GEM object and so not valid for access from userspace. This makes it useful
157 * for hardware interfaces like ringbuffers (which are pinned from the time
158 * the request is written to the time the hardware stops accessing it), but
159 * not for contexts (which need to be preserved when not active for later
160 * reuse). Note that it is not cleared upon allocation.
161 */
162struct drm_i915_gem_object *
163i915_gem_object_create_internal(struct drm_i915_private *i915,
164				phys_addr_t size)
165{
166	static struct lock_class_key lock_class;
167	struct drm_i915_gem_object *obj;
168	unsigned int cache_level;
169
170	GEM_BUG_ON(!size);
171	GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
172
173	if (overflows_type(size, obj->base.size))
174		return ERR_PTR(-E2BIG);
175
176	obj = i915_gem_object_alloc();
177	if (!obj)
178		return ERR_PTR(-ENOMEM);
179
180	drm_gem_private_object_init(&i915->drm, &obj->base, size);
181	i915_gem_object_init(obj, &i915_gem_object_internal_ops, &lock_class);
182
183	/*
184	 * Mark the object as volatile, such that the pages are marked as
185	 * dontneed whilst they are still pinned. As soon as they are unpinned
186	 * they are allowed to be reaped by the shrinker, and the caller is
187	 * expected to repopulate - the contents of this object are only valid
188	 * whilst active and pinned.
189	 */
190	i915_gem_object_set_volatile(obj);
191
192	obj->read_domains = I915_GEM_DOMAIN_CPU;
193	obj->write_domain = I915_GEM_DOMAIN_CPU;
194
195	cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
196	i915_gem_object_set_cache_coherency(obj, cache_level);
197
198	return obj;
199}