i915_mm.c revision 1.3 
1/*
2 * Copyright �� 2014 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 *
23 */
24
25#include <linux/mm.h>
26#include <linux/io-mapping.h>
27
28
29#include "i915_drv.h"
30
31struct remap_pfn {
32	struct mm_struct *mm;
33	unsigned long pfn;
34	pgprot_t prot;
35
36	struct sgt_iter sgt;
37	resource_size_t iobase;
38};
39
40#ifdef notyet
41static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
42{
43	struct remap_pfn *r = data;
44
45	/* Special PTE are not associated with any struct vm_page */
46	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
47	r->pfn++;
48
49	return 0;
50}
51#endif
52
53#define use_dma(io) ((io) != -1)
54
55static inline unsigned long sgt_pfn(const struct remap_pfn *r)
56{
57	if (use_dma(r->iobase))
58		return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
59	else
60		return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
61}
62
63#ifdef notyet
64
65static int remap_sg(pte_t *pte, unsigned long addr, void *data)
66{
67	struct remap_pfn *r = data;
68
69	if (GEM_WARN_ON(!r->sgt.pfn))
70		return -EINVAL;
71
72	/* Special PTE are not associated with any struct vm_page */
73	set_pte_at(r->mm, addr, pte,
74		   pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
75	r->pfn++; /* track insertions in case we need to unwind later */
76
77	r->sgt.curr += PAGE_SIZE;
78	if (r->sgt.curr >= r->sgt.max)
79		r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
80
81	return 0;
82}
83
84/**
85 * remap_io_mapping - remap an IO mapping to userspace
86 * @vma: user vma to map to
87 * @addr: target user address to start at
88 * @pfn: physical address of kernel memory
89 * @size: size of map area
90 * @iomap: the source io_mapping
91 *
92 *  Note: this is only safe if the mm semaphore is held when called.
93 */
94int remap_io_mapping(struct vm_area_struct *vma,
95		     unsigned long addr, unsigned long pfn, unsigned long size,
96		     struct io_mapping *iomap)
97{
98	struct remap_pfn r;
99	int err;
100
101#define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
102	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
103
104	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
105	r.mm = vma->vm_mm;
106	r.pfn = pfn;
107	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
108			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
109
110	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
111	if (unlikely(err)) {
112		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
113		return err;
114	}
115
116	return 0;
117}
118
119/**
120 * remap_io_sg - remap an IO mapping to userspace
121 * @vma: user vma to map to
122 * @addr: target user address to start at
123 * @size: size of map area
124 * @sgl: Start sg entry
125 * @iobase: Use stored dma address offset by this address or pfn if -1
126 *
127 *  Note: this is only safe if the mm semaphore is held when called.
128 */
129int remap_io_sg(struct vm_area_struct *vma,
130		unsigned long addr, unsigned long size,
131		struct scatterlist *sgl, resource_size_t iobase)
132{
133	struct remap_pfn r = {
134		.mm = vma->vm_mm,
135		.prot = vma->vm_page_prot,
136		.sgt = __sgt_iter(sgl, use_dma(iobase)),
137		.iobase = iobase,
138	};
139	int err;
140
141	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
142	GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
143
144	if (!use_dma(iobase))
145		flush_cache_range(vma, addr, size);
146
147	err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
148	if (unlikely(err)) {
149		zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
150		return err;
151	}
152
153	return 0;
154}
155
156#endif /* notyet */
157