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
 10#include "i915_drv.h"
 11#include "i915_gem.h"
 12#include "i915_gem_internal.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 npages;
 39	int max_order = MAX_ORDER;
 40	unsigned int max_segment;
 41	gfp_t gfp;
 42
 43	max_segment = i915_sg_segment_size(i915->drm.dev) >> PAGE_SHIFT;
 44	max_order = min(max_order, get_order(max_segment));
 45
 46	gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
 47	if (IS_I965GM(i915) || IS_I965G(i915)) {
 48		/* 965gm cannot relocate objects above 4GiB. */
 49		gfp &= ~__GFP_HIGHMEM;
 50		gfp |= __GFP_DMA32;
 51	}
 52
 53create_st:
 54	st = kmalloc(sizeof(*st), GFP_KERNEL);
 55	if (!st)
 56		return -ENOMEM;
 57
 58	npages = obj->base.size / PAGE_SIZE;
 59	if (sg_alloc_table(st, npages, GFP_KERNEL)) {
 60		kfree(st);
 61		return -ENOMEM;
 62	}
 63
 64	sg = st->sgl;
 65	st->nents = 0;
 66
 67	do {
 68		int order = min(fls(npages) - 1, max_order);
 69		struct page *page;
 70
 71		do {
 72			page = alloc_pages(gfp | (order ? QUIET : MAYFAIL),
 73					   order);
 74			if (page)
 75				break;
 76			if (!order--)
 77				goto err;
 78
 79			/* Limit subsequent allocations as well */
 80			max_order = order;
 81		} while (1);
 82
 83		sg_set_page(sg, page, PAGE_SIZE << order, 0);
 84		st->nents++;
 85
 86		npages -= 1 << order;
 87		if (!npages) {
 88			sg_mark_end(sg);
 89			break;
 90		}
 91
 92		sg = __sg_next(sg);
 93	} while (1);
 94
 95	if (i915_gem_gtt_prepare_pages(obj, st)) {
 96		/* Failed to dma-map try again with single page sg segments */
 97		if (get_order(st->sgl->length)) {
 98			internal_free_pages(st);
 99			max_order = 0;
100			goto create_st;
101		}
102		goto err;
103	}
104
105	__i915_gem_object_set_pages(obj, st);
106
107	return 0;
108
109err:
110	sg_set_page(sg, NULL, 0, 0);
111	sg_mark_end(sg);
112	internal_free_pages(st);
113
114	return -ENOMEM;
115}
116
117static void i915_gem_object_put_pages_internal(struct drm_i915_gem_object *obj,
118					       struct sg_table *pages)
119{
120	i915_gem_gtt_finish_pages(obj, pages);
121	internal_free_pages(pages);
122
123	obj->mm.dirty = false;
124
125	__start_cpu_write(obj);
126}
127
128static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
129	.name = "i915_gem_object_internal",
130	.flags = I915_GEM_OBJECT_IS_SHRINKABLE,
131	.get_pages = i915_gem_object_get_pages_internal,
132	.put_pages = i915_gem_object_put_pages_internal,
133};
134
135struct drm_i915_gem_object *
136__i915_gem_object_create_internal(struct drm_i915_private *i915,
137				  const struct drm_i915_gem_object_ops *ops,
138				  phys_addr_t size)
139{
140	static struct lock_class_key lock_class;
141	struct drm_i915_gem_object *obj;
142	unsigned int cache_level;
143
144	GEM_BUG_ON(!size);
145	GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
146
147	if (overflows_type(size, obj->base.size))
148		return ERR_PTR(-E2BIG);
149
150	obj = i915_gem_object_alloc();
151	if (!obj)
152		return ERR_PTR(-ENOMEM);
153
154	drm_gem_private_object_init(&i915->drm, &obj->base, size);
155	i915_gem_object_init(obj, ops, &lock_class, 0);
156	obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;
157
158	/*
159	 * Mark the object as volatile, such that the pages are marked as
160	 * dontneed whilst they are still pinned. As soon as they are unpinned
161	 * they are allowed to be reaped by the shrinker, and the caller is
162	 * expected to repopulate - the contents of this object are only valid
163	 * whilst active and pinned.
164	 */
165	i915_gem_object_set_volatile(obj);
166
167	obj->read_domains = I915_GEM_DOMAIN_CPU;
168	obj->write_domain = I915_GEM_DOMAIN_CPU;
169
170	cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
171	i915_gem_object_set_cache_coherency(obj, cache_level);
172
173	return obj;
174}
175
176/**
177 * i915_gem_object_create_internal: create an object with volatile pages
178 * @i915: the i915 device
179 * @size: the size in bytes of backing storage to allocate for the object
180 *
181 * Creates a new object that wraps some internal memory for private use.
182 * This object is not backed by swappable storage, and as such its contents
183 * are volatile and only valid whilst pinned. If the object is reaped by the
184 * shrinker, its pages and data will be discarded. Equally, it is not a full
185 * GEM object and so not valid for access from userspace. This makes it useful
186 * for hardware interfaces like ringbuffers (which are pinned from the time
187 * the request is written to the time the hardware stops accessing it), but
188 * not for contexts (which need to be preserved when not active for later
189 * reuse). Note that it is not cleared upon allocation.
190 */
191struct drm_i915_gem_object *
192i915_gem_object_create_internal(struct drm_i915_private *i915,
193				phys_addr_t size)
194{
195	return __i915_gem_object_create_internal(i915, &i915_gem_object_internal_ops, size);
196}