drivers/vfio/pci/vfio_pci_rdwr.c

   1 /*
   2  * VFIO PCI I/O Port & MMIO access
   3  *
   4  * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
   5  *     Author: Alex Williamson <alex.williamson@redhat.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * Derived from original vfio:
  12  * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
  13  * Author: Tom Lyon, pugs@cisco.com
  14  */
  15
  16 #include <linux/fs.h>
  17 #include <linux/pci.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/io.h>
  20
  21 #include "vfio_pci_private.h"
  22
  23 /* I/O Port BAR access */
  24 ssize_t vfio_pci_io_readwrite(struct vfio_pci_device *vdev, char __user *buf,
  25                               size_t count, loff_t *ppos, bool iswrite)
  26 {
  27         struct pci_dev *pdev = vdev->pdev;
  28         loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
  29         int bar = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
  30         void __iomem *io;
  31         size_t done = 0;
  32
  33         if (!pci_resource_start(pdev, bar))
  34                 return -EINVAL;
  35
  36         if (pos + count > pci_resource_len(pdev, bar))
  37                 return -EINVAL;
  38
  39         if (!vdev->barmap[bar]) {
  40                 int ret;
  41
  42                 ret = pci_request_selected_regions(pdev, 1 << bar, "vfio");
  43                 if (ret)
  44                         return ret;
  45
  46                 vdev->barmap[bar] = pci_iomap(pdev, bar, 0);
  47
  48                 if (!vdev->barmap[bar]) {
  49                         pci_release_selected_regions(pdev, 1 << bar);
  50                         return -EINVAL;
  51                 }
  52         }
  53
  54         io = vdev->barmap[bar];
  55
  56         while (count) {
  57                 int filled;
  58
  59                 if (count >= 3 && !(pos % 4)) {
  60                         __le32 val;
  61
  62                         if (iswrite) {
  63                                 if (copy_from_user(&val, buf, 4))
  64                                         return -EFAULT;
  65
  66                                 iowrite32(le32_to_cpu(val), io + pos);
  67                         } else {
  68                                 val = cpu_to_le32(ioread32(io + pos));
  69
  70                                 if (copy_to_user(buf, &val, 4))
  71                                         return -EFAULT;
  72                         }
  73
  74                         filled = 4;
  75
  76                 } else if ((pos % 2) == 0 && count >= 2) {
  77                         __le16 val;
  78
  79                         if (iswrite) {
  80                                 if (copy_from_user(&val, buf, 2))
  81                                         return -EFAULT;
  82
  83                                 iowrite16(le16_to_cpu(val), io + pos);
  84                         } else {
  85                                 val = cpu_to_le16(ioread16(io + pos));
  86
  87                                 if (copy_to_user(buf, &val, 2))
  88                                         return -EFAULT;
  89                         }
  90
  91                         filled = 2;
  92                 } else {
  93                         u8 val;
  94
  95                         if (iswrite) {
  96                                 if (copy_from_user(&val, buf, 1))
  97                                         return -EFAULT;
  98
  99                                 iowrite8(val, io + pos);
 100                         } else {
 101                                 val = ioread8(io + pos);
 102
 103                                 if (copy_to_user(buf, &val, 1))
 104                                         return -EFAULT;
 105                         }
 106
 107                         filled = 1;
 108                 }
 109
 110                 count -= filled;
 111                 done += filled;
 112                 buf += filled;
 113                 pos += filled;
 114         }
 115
 116         *ppos += done;
 117
 118         return done;
 119 }
 120
 121 /*
 122  * MMIO BAR access
 123  * We handle two excluded ranges here as well, if the user tries to read
 124  * the ROM beyond what PCI tells us is available or the MSI-X table region,
 125  * we return 0xFF and writes are dropped.
 126  */
 127 ssize_t vfio_pci_mem_readwrite(struct vfio_pci_device *vdev, char __user *buf,
 128                                size_t count, loff_t *ppos, bool iswrite)
 129 {
 130         struct pci_dev *pdev = vdev->pdev;
 131         loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
 132         int bar = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
 133         void __iomem *io;
 134         resource_size_t end;
 135         size_t done = 0;
 136         size_t x_start = 0, x_end = 0; /* excluded range */
 137
 138         if (!pci_resource_start(pdev, bar))
 139                 return -EINVAL;
 140
 141         end = pci_resource_len(pdev, bar);
 142
 143         if (pos > end)
 144                 return -EINVAL;
 145
 146         if (pos == end)
 147                 return 0;
 148
 149         if (pos + count > end)
 150                 count = end - pos;
 151
 152         if (bar == PCI_ROM_RESOURCE) {
 153                 io = pci_map_rom(pdev, &x_start);
 154                 x_end = end;
 155         } else {
 156                 if (!vdev->barmap[bar]) {
 157                         int ret;
 158
 159                         ret = pci_request_selected_regions(pdev, 1 << bar,
 160                                                            "vfio");
 161                         if (ret)
 162                                 return ret;
 163
 164                         vdev->barmap[bar] = pci_iomap(pdev, bar, 0);
 165
 166                         if (!vdev->barmap[bar]) {
 167                                 pci_release_selected_regions(pdev, 1 << bar);
 168                                 return -EINVAL;
 169                         }
 170                 }
 171
 172                 io = vdev->barmap[bar];
 173
 174                 if (bar == vdev->msix_bar) {
 175                         x_start = vdev->msix_offset;
 176                         x_end = vdev->msix_offset + vdev->msix_size;
 177                 }
 178         }
 179
 180         if (!io)
 181                 return -EINVAL;
 182
 183         while (count) {
 184                 size_t fillable, filled;
 185
 186                 if (pos < x_start)
 187                         fillable = x_start - pos;
 188                 else if (pos >= x_end)
 189                         fillable = end - pos;
 190                 else
 191                         fillable = 0;
 192
 193                 if (fillable >= 4 && !(pos % 4) && (count >= 4)) {
 194                         __le32 val;
 195
 196                         if (iswrite) {
 197                                 if (copy_from_user(&val, buf, 4))
 198                                         goto out;
 199
 200                                 iowrite32(le32_to_cpu(val), io + pos);
 201                         } else {
 202                                 val = cpu_to_le32(ioread32(io + pos));
 203
 204                                 if (copy_to_user(buf, &val, 4))
 205                                         goto out;
 206                         }
 207
 208                         filled = 4;
 209                 } else if (fillable >= 2 && !(pos % 2) && (count >= 2)) {
 210                         __le16 val;
 211
 212                         if (iswrite) {
 213                                 if (copy_from_user(&val, buf, 2))
 214                                         goto out;
 215
 216                                 iowrite16(le16_to_cpu(val), io + pos);
 217                         } else {
 218                                 val = cpu_to_le16(ioread16(io + pos));
 219
 220                                 if (copy_to_user(buf, &val, 2))
 221                                         goto out;
 222                         }
 223
 224                         filled = 2;
 225                 } else if (fillable) {
 226                         u8 val;
 227
 228                         if (iswrite) {
 229                                 if (copy_from_user(&val, buf, 1))
 230                                         goto out;
 231
 232                                 iowrite8(val, io + pos);
 233                         } else {
 234                                 val = ioread8(io + pos);
 235
 236                                 if (copy_to_user(buf, &val, 1))
 237                                         goto out;
 238                         }
 239
 240                         filled = 1;
 241                 } else {
 242                         /* Drop writes, fill reads with FF */
 243                         filled = min((size_t)(x_end - pos), count);
 244                         if (!iswrite) {
 245                                 char val = 0xFF;
 246                                 size_t i;
 247
 248                                 for (i = 0; i < filled; i++) {
 249                                         if (put_user(val, buf + i))
 250                                                 goto out;
 251                                 }
 252                         }
 253
 254                 }
 255
 256                 count -= filled;
 257                 done += filled;
 258                 buf += filled;
 259                 pos += filled;
 260         }
 261
 262         *ppos += done;
 263
 264 out:
 265         if (bar == PCI_ROM_RESOURCE)
 266                 pci_unmap_rom(pdev, io);
 267
 268         return count ? -EFAULT : done;
 269 }