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 <drm/i915_drm.h>
 12
 13#include "i915_drv.h"
 14#include "i915_gem.h"
 15#include "i915_gem_object.h"
 16#include "i915_scatterlist.h"
 17#include "i915_utils.h"
 18
 19#define QUIET (__GFP_NORETRY | __GFP_NOWARN)
 20#define MAYFAIL (__GFP_RETRY_MAYFAIL | __GFP_NOWARN)
 21
 22static void internal_free_pages(struct sg_table *st)
 23{
 24	struct scatterlist *sg;
 25
 26	for (sg = st->sgl; sg; sg = __sg_next(sg)) {
 27		if (sg_page(sg))
 28			__free_pages(sg_page(sg), get_order(sg->length));
 29	}
 30
 31	sg_free_table(st);
 32	kfree(st);
 33}
 34
 35static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
 36{
 37	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 38	struct sg_table *st;
 39	struct scatterlist *sg;
 40	unsigned int sg_page_sizes;
 41	unsigned int npages;
 42	int max_order;
 43	gfp_t gfp;
 44
 45	max_order = MAX_ORDER;
 46#ifdef CONFIG_SWIOTLB
 47	if (swiotlb_nr_tbl()) {
 48		unsigned int max_segment;
 49
 50		max_segment = swiotlb_max_segment();
 51		if (max_segment) {
 52			max_segment = max_t(unsigned int, max_segment,
 53					    PAGE_SIZE) >> PAGE_SHIFT;
 54			max_order = min(max_order, ilog2(max_segment));
 55		}
 56	}
 57#endif
 58
 59	gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
 60	if (IS_I965GM(i915) || IS_I965G(i915)) {
 61		/* 965gm cannot relocate objects above 4GiB. */
 62		gfp &= ~__GFP_HIGHMEM;
 63		gfp |= __GFP_DMA32;
 64	}
 65
 66create_st:
 67	st = kmalloc(sizeof(*st), GFP_KERNEL);
 68	if (!st)
 69		return -ENOMEM;
 70
 71	npages = obj->base.size / PAGE_SIZE;
 72	if (sg_alloc_table(st, npages, GFP_KERNEL)) {
 73		kfree(st);
 74		return -ENOMEM;
 75	}
 76
 77	sg = st->sgl;
 78	st->nents = 0;
 79	sg_page_sizes = 0;
 80
 81	do {
 82		int order = min(fls(npages) - 1, max_order);
 83		struct page *page;
 84
 85		do {
 86			page = alloc_pages(gfp | (order ? QUIET : MAYFAIL),
 87					   order);
 88			if (page)
 89				break;
 90			if (!order--)
 91				goto err;
 92
 93			/* Limit subsequent allocations as well */
 94			max_order = order;
 95		} while (1);
 96
 97		sg_set_page(sg, page, PAGE_SIZE << order, 0);
 98		sg_page_sizes |= PAGE_SIZE << order;
 99		st->nents++;
100
101		npages -= 1 << order;
102		if (!npages) {
103			sg_mark_end(sg);
104			break;
105		}
106
107		sg = __sg_next(sg);
108	} while (1);
109
110	if (i915_gem_gtt_prepare_pages(obj, st)) {
111		/* Failed to dma-map try again with single page sg segments */
112		if (get_order(st->sgl->length)) {
113			internal_free_pages(st);
114			max_order = 0;
115			goto create_st;
116		}
117		goto err;
118	}
119
120	/* Mark the pages as dontneed whilst they are still pinned. As soon
121	 * as they are unpinned they are allowed to be reaped by the shrinker,
122	 * and the caller is expected to repopulate - the contents of this
123	 * object are only valid whilst active and pinned.
124	 */
125	obj->mm.madv = I915_MADV_DONTNEED;
126
127	__i915_gem_object_set_pages(obj, st, sg_page_sizes);
128
129	return 0;
130
131err:
132	sg_set_page(sg, NULL, 0, 0);
133	sg_mark_end(sg);
134	internal_free_pages(st);
135
136	return -ENOMEM;
137}
138
139static void i915_gem_object_put_pages_internal(struct drm_i915_gem_object *obj,
140					       struct sg_table *pages)
141{
142	i915_gem_gtt_finish_pages(obj, pages);
143	internal_free_pages(pages);
144
145	obj->mm.dirty = false;
146	obj->mm.madv = I915_MADV_WILLNEED;
147}
148
149static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
150	.flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE |
151		 I915_GEM_OBJECT_IS_SHRINKABLE,
152	.get_pages = i915_gem_object_get_pages_internal,
153	.put_pages = i915_gem_object_put_pages_internal,
154};
155
156/**
157 * i915_gem_object_create_internal: create an object with volatile pages
158 * @i915: the i915 device
159 * @size: the size in bytes of backing storage to allocate for the object
160 *
161 * Creates a new object that wraps some internal memory for private use.
162 * This object is not backed by swappable storage, and as such its contents
163 * are volatile and only valid whilst pinned. If the object is reaped by the
164 * shrinker, its pages and data will be discarded. Equally, it is not a full
165 * GEM object and so not valid for access from userspace. This makes it useful
166 * for hardware interfaces like ringbuffers (which are pinned from the time
167 * the request is written to the time the hardware stops accessing it), but
168 * not for contexts (which need to be preserved when not active for later
169 * reuse). Note that it is not cleared upon allocation.
170 */
171struct drm_i915_gem_object *
172i915_gem_object_create_internal(struct drm_i915_private *i915,
173				phys_addr_t size)
174{
175	struct drm_i915_gem_object *obj;
176	unsigned int cache_level;
177
178	GEM_BUG_ON(!size);
179	GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
180
181	if (overflows_type(size, obj->base.size))
182		return ERR_PTR(-E2BIG);
183
184	obj = i915_gem_object_alloc();
185	if (!obj)
186		return ERR_PTR(-ENOMEM);
187
188	drm_gem_private_object_init(&i915->drm, &obj->base, size);
189	i915_gem_object_init(obj, &i915_gem_object_internal_ops);
190
191	obj->read_domains = I915_GEM_DOMAIN_CPU;
192	obj->write_domain = I915_GEM_DOMAIN_CPU;
193
194	cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
195	i915_gem_object_set_cache_coherency(obj, cache_level);
196
197	return obj;
198}