i915_gem_internal.c

  1// SPDX-License-Identifier: MIT
  2/*
  3 * Copyright © 2014-2016 Intel Corporation
  4 */
  5
  6#include <linux/scatterlist.h>
  7#include <linux/slab.h>
  8
  9#include "i915_drv.h"
 10#include "i915_gem.h"
 11#include "i915_gem_internal.h"
 12#include "i915_gem_object.h"
 13#include "i915_scatterlist.h"
 14#include "i915_utils.h"
 15
 16#define QUIET (__GFP_NORETRY | __GFP_NOWARN)
 17#define MAYFAIL (__GFP_RETRY_MAYFAIL | __GFP_NOWARN)
 18
 19static void internal_free_pages(struct sg_table *st)
 20{
 21	struct scatterlist *sg;
 22
 23	for (sg = st->sgl; sg; sg = __sg_next(sg)) {
 24		if (sg_page(sg))
 25			__free_pages(sg_page(sg), get_order(sg->length));
 26	}
 27
 28	sg_free_table(st);
 29	kfree(st);
 30}
 31
 32static int i915_gem_object_get_pages_internal(struct drm_i915_gem_object *obj)
 33{
 34	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 35	struct sg_table *st;
 36	struct scatterlist *sg;
 37	unsigned int npages; /* restricted by sg_alloc_table */
 38	int max_order = MAX_PAGE_ORDER;
 39	unsigned int max_segment;
 40	gfp_t gfp;
 41
 42	if (overflows_type(obj->base.size >> PAGE_SHIFT, npages))
 43		return -E2BIG;
 44
 45	npages = obj->base.size >> PAGE_SHIFT;
 46	max_segment = i915_sg_segment_size(i915->drm.dev) >> PAGE_SHIFT;
 47	max_order = min(max_order, get_order(max_segment));
 48
 49	gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
 50	if (IS_I965GM(i915) || IS_I965G(i915)) {
 51		/* 965gm cannot relocate objects above 4GiB. */
 52		gfp &= ~__GFP_HIGHMEM;
 53		gfp |= __GFP_DMA32;
 54	}
 55
 56create_st:
 57	st = kmalloc(sizeof(*st), GFP_KERNEL);
 58	if (!st)
 59		return -ENOMEM;
 60
 61	if (sg_alloc_table(st, npages, GFP_KERNEL)) {
 62		kfree(st);
 63		return -ENOMEM;
 64	}
 65
 66	sg = st->sgl;
 67	st->nents = 0;
 68
 69	do {
 70		int order = min(fls(npages) - 1, max_order);
 71		struct page *page;
 72
 73		do {
 74			page = alloc_pages(gfp | (order ? QUIET : MAYFAIL),
 75					   order);
 76			if (page)
 77				break;
 78			if (!order--)
 79				goto err;
 80
 81			/* Limit subsequent allocations as well */
 82			max_order = order;
 83		} while (1);
 84
 85		sg_set_page(sg, page, PAGE_SIZE << order, 0);
 86		st->nents++;
 87
 88		npages -= 1 << order;
 89		if (!npages) {
 90			sg_mark_end(sg);
 91			break;
 92		}
 93
 94		sg = __sg_next(sg);
 95	} while (1);
 96
 97	if (i915_gem_gtt_prepare_pages(obj, st)) {
 98		/* Failed to dma-map try again with single page sg segments */
 99		if (get_order(st->sgl->length)) {
100			internal_free_pages(st);
101			max_order = 0;
102			goto create_st;
103		}
104		goto err;
105	}
106
107	__i915_gem_object_set_pages(obj, st);
108
109	return 0;
110
111err:
112	sg_set_page(sg, NULL, 0, 0);
113	sg_mark_end(sg);
114	internal_free_pages(st);
115
116	return -ENOMEM;
117}
118
119static void i915_gem_object_put_pages_internal(struct drm_i915_gem_object *obj,
120					       struct sg_table *pages)
121{
122	i915_gem_gtt_finish_pages(obj, pages);
123	internal_free_pages(pages);
124
125	obj->mm.dirty = false;
126
127	__start_cpu_write(obj);
128}
129
130static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
131	.name = "i915_gem_object_internal",
132	.flags = I915_GEM_OBJECT_IS_SHRINKABLE,
133	.get_pages = i915_gem_object_get_pages_internal,
134	.put_pages = i915_gem_object_put_pages_internal,
135};
136
137struct drm_i915_gem_object *
138__i915_gem_object_create_internal(struct drm_i915_private *i915,
139				  const struct drm_i915_gem_object_ops *ops,
140				  phys_addr_t size)
141{
142	static struct lock_class_key lock_class;
143	struct drm_i915_gem_object *obj;
144	unsigned int cache_level;
145
146	GEM_BUG_ON(!size);
147	GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
148
149	if (overflows_type(size, obj->base.size))
150		return ERR_PTR(-E2BIG);
151
152	obj = i915_gem_object_alloc();
153	if (!obj)
154		return ERR_PTR(-ENOMEM);
155
156	drm_gem_private_object_init(&i915->drm, &obj->base, size);
157	i915_gem_object_init(obj, ops, &lock_class, 0);
158	obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;
159
160	/*
161	 * Mark the object as volatile, such that the pages are marked as
162	 * dontneed whilst they are still pinned. As soon as they are unpinned
163	 * they are allowed to be reaped by the shrinker, and the caller is
164	 * expected to repopulate - the contents of this object are only valid
165	 * whilst active and pinned.
166	 */
167	i915_gem_object_set_volatile(obj);
168
169	obj->read_domains = I915_GEM_DOMAIN_CPU;
170	obj->write_domain = I915_GEM_DOMAIN_CPU;
171
172	cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
173	i915_gem_object_set_cache_coherency(obj, cache_level);
174
175	return obj;
176}
177
178/**
179 * i915_gem_object_create_internal: create an object with volatile pages
180 * @i915: the i915 device
181 * @size: the size in bytes of backing storage to allocate for the object
182 *
183 * Creates a new object that wraps some internal memory for private use.
184 * This object is not backed by swappable storage, and as such its contents
185 * are volatile and only valid whilst pinned. If the object is reaped by the
186 * shrinker, its pages and data will be discarded. Equally, it is not a full
187 * GEM object and so not valid for access from userspace. This makes it useful
188 * for hardware interfaces like ringbuffers (which are pinned from the time
189 * the request is written to the time the hardware stops accessing it), but
190 * not for contexts (which need to be preserved when not active for later
191 * reuse). Note that it is not cleared upon allocation.
192 */
193struct drm_i915_gem_object *
194i915_gem_object_create_internal(struct drm_i915_private *i915,
195				phys_addr_t size)
196{
197	return __i915_gem_object_create_internal(i915, &i915_gem_object_internal_ops, size);
198}