1 /* $NetBSD: i915_mm.c,v 1.2 2021/12/18 23:45:28 riastradh Exp $ */
2
3 /*
4 * Copyright © 2014 Intel Corporation
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the next
14 * paragraph) shall be included in all copies or substantial portions of the
15 * Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
23 * IN THE SOFTWARE.
24 *
25 */
26
27 #include <sys/cdefs.h>
28 __KERNEL_RCSID(0, "$NetBSD: i915_mm.c,v 1.2 2021/12/18 23:45:28 riastradh Exp $");
29
30 #include <linux/mm.h>
31 #include <linux/io-mapping.h>
32
33 #include <asm/pgtable.h>
34
35 #include "i915_drv.h"
36
37 struct remap_pfn {
38 struct mm_struct *mm;
39 unsigned long pfn;
40 pgprot_t prot;
41
42 struct sgt_iter sgt;
43 resource_size_t iobase;
44 };
45
remap_pfn(pte_t * pte,unsigned long addr,void * data)46 static int remap_pfn(pte_t *pte, unsigned long addr, void *data)
47 {
48 struct remap_pfn *r = data;
49
50 /* Special PTE are not associated with any struct page */
51 set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
52 r->pfn++;
53
54 return 0;
55 }
56
57 #define use_dma(io) ((io) != -1)
58
sgt_pfn(const struct remap_pfn * r)59 static inline unsigned long sgt_pfn(const struct remap_pfn *r)
60 {
61 if (use_dma(r->iobase))
62 return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
63 else
64 return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
65 }
66
remap_sg(pte_t * pte,unsigned long addr,void * data)67 static int remap_sg(pte_t *pte, unsigned long addr, void *data)
68 {
69 struct remap_pfn *r = data;
70
71 if (GEM_WARN_ON(!r->sgt.pfn))
72 return -EINVAL;
73
74 /* Special PTE are not associated with any struct page */
75 set_pte_at(r->mm, addr, pte,
76 pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
77 r->pfn++; /* track insertions in case we need to unwind later */
78
79 r->sgt.curr += PAGE_SIZE;
80 if (r->sgt.curr >= r->sgt.max)
81 r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
82
83 return 0;
84 }
85
86 /**
87 * remap_io_mapping - remap an IO mapping to userspace
88 * @vma: user vma to map to
89 * @addr: target user address to start at
90 * @pfn: physical address of kernel memory
91 * @size: size of map area
92 * @iomap: the source io_mapping
93 *
94 * Note: this is only safe if the mm semaphore is held when called.
95 */
remap_io_mapping(struct vm_area_struct * vma,unsigned long addr,unsigned long pfn,unsigned long size,struct io_mapping * iomap)96 int remap_io_mapping(struct vm_area_struct *vma,
97 unsigned long addr, unsigned long pfn, unsigned long size,
98 struct io_mapping *iomap)
99 {
100 struct remap_pfn r;
101 int err;
102
103 #define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
104 GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
105
106 /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
107 r.mm = vma->vm_mm;
108 r.pfn = pfn;
109 r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
110 (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
111
112 err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
113 if (unlikely(err)) {
114 zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
115 return err;
116 }
117
118 return 0;
119 }
120
121 /**
122 * remap_io_sg - remap an IO mapping to userspace
123 * @vma: user vma to map to
124 * @addr: target user address to start at
125 * @size: size of map area
126 * @sgl: Start sg entry
127 * @iobase: Use stored dma address offset by this address or pfn if -1
128 *
129 * Note: this is only safe if the mm semaphore is held when called.
130 */
remap_io_sg(struct vm_area_struct * vma,unsigned long addr,unsigned long size,struct scatterlist * sgl,resource_size_t iobase)131 int remap_io_sg(struct vm_area_struct *vma,
132 unsigned long addr, unsigned long size,
133 struct scatterlist *sgl, resource_size_t iobase)
134 {
135 struct remap_pfn r = {
136 .mm = vma->vm_mm,
137 .prot = vma->vm_page_prot,
138 .sgt = __sgt_iter(sgl, use_dma(iobase)),
139 .iobase = iobase,
140 };
141 int err;
142
143 /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
144 GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
145
146 if (!use_dma(iobase))
147 flush_cache_range(vma, addr, size);
148
149 err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
150 if (unlikely(err)) {
151 zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
152 return err;
153 }
154
155 return 0;
156 }
157