drivers/gpu/drm/i915/i915_mm.c

   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 #include <asm/pgtable.h>
  29
  30 #include "i915_drv.h"
  31
  32 struct remap_pfn {
  33         struct mm_struct *mm;
  34         unsigned long pfn;
  35         pgprot_t prot;
  36
  37         struct sgt_iter sgt;
  38         resource_size_t iobase;
  39 };
  40
  41 static 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 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
  52 #define use_dma(io) ((io) != -1)
  53
  54 static inline unsigned long sgt_pfn(const struct remap_pfn *r)
  55 {
  56         if (use_dma(r->iobase))
  57                 return (r->sgt.dma + r->sgt.curr + r->iobase) >> PAGE_SHIFT;
  58         else
  59                 return r->sgt.pfn + (r->sgt.curr >> PAGE_SHIFT);
  60 }
  61
  62 static int remap_sg(pte_t *pte, unsigned long addr, void *data)
  63 {
  64         struct remap_pfn *r = data;
  65
  66         if (GEM_WARN_ON(!r->sgt.pfn))
  67                 return -EINVAL;
  68
  69         /* Special PTE are not associated with any struct page */
  70         set_pte_at(r->mm, addr, pte,
  71                    pte_mkspecial(pfn_pte(sgt_pfn(r), r->prot)));
  72         r->pfn++; /* track insertions in case we need to unwind later */
  73
  74         r->sgt.curr += PAGE_SIZE;
  75         if (r->sgt.curr >= r->sgt.max)
  76                 r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));
  77
  78         return 0;
  79 }
  80
  81 /**
  82  * remap_io_mapping - remap an IO mapping to userspace
  83  * @vma: user vma to map to
  84  * @addr: target user address to start at
  85  * @pfn: physical address of kernel memory
  86  * @size: size of map area
  87  * @iomap: the source io_mapping
  88  *
  89  *  Note: this is only safe if the mm semaphore is held when called.
  90  */
  91 int remap_io_mapping(struct vm_area_struct *vma,
  92                      unsigned long addr, unsigned long pfn, unsigned long size,
  93                      struct io_mapping *iomap)
  94 {
  95         struct remap_pfn r;
  96         int err;
  97
  98 #define EXPECTED_FLAGS (VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)
  99         GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
 100
 101         /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
 102         r.mm = vma->vm_mm;
 103         r.pfn = pfn;
 104         r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
 105                           (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
 106
 107         err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
 108         if (unlikely(err)) {
 109                 zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
 110                 return err;
 111         }
 112
 113         return 0;
 114 }
 115
 116 /**
 117  * remap_io_sg - remap an IO mapping to userspace
 118  * @vma: user vma to map to
 119  * @addr: target user address to start at
 120  * @size: size of map area
 121  * @sgl: Start sg entry
 122  * @iobase: Use stored dma address offset by this address or pfn if -1
 123  *
 124  *  Note: this is only safe if the mm semaphore is held when called.
 125  */
 126 int remap_io_sg(struct vm_area_struct *vma,
 127                 unsigned long addr, unsigned long size,
 128                 struct scatterlist *sgl, resource_size_t iobase)
 129 {
 130         struct remap_pfn r = {
 131                 .mm = vma->vm_mm,
 132                 .prot = vma->vm_page_prot,
 133                 .sgt = __sgt_iter(sgl, use_dma(iobase)),
 134                 .iobase = iobase,
 135         };
 136         int err;
 137
 138         /* We rely on prevalidation of the io-mapping to skip track_pfn(). */
 139         GEM_BUG_ON((vma->vm_flags & EXPECTED_FLAGS) != EXPECTED_FLAGS);
 140
 141         if (!use_dma(iobase))
 142                 flush_cache_range(vma, addr, size);
 143
 144         err = apply_to_page_range(r.mm, addr, size, remap_sg, &r);
 145         if (unlikely(err)) {
 146                 zap_vma_ptes(vma, addr, r.pfn << PAGE_SHIFT);
 147                 return err;
 148         }
 149
 150         return 0;
 151 }