kernel/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 #include <linux/vgaarb.h>
  21
  22 #include "vfio_pci_private.h"
  23
  24 /*
  25  * Read or write from an __iomem region (MMIO or I/O port) with an excluded
  26  * range which is inaccessible.  The excluded range drops writes and fills
  27  * reads with -1.  This is intended for handling MSI-X vector tables and
  28  * leftover space for ROM BARs.
  29  */
  30 static ssize_t do_io_rw(void __iomem *io, char __user *buf,
  31                         loff_t off, size_t count, size_t x_start,
  32                         size_t x_end, bool iswrite)
  33 {
  34         ssize_t done = 0;
  35
  36         while (count) {
  37                 size_t fillable, filled;
  38
  39                 if (off < x_start)
  40                         fillable = min(count, (size_t)(x_start - off));
  41                 else if (off >= x_end)
  42                         fillable = count;
  43                 else
  44                         fillable = 0;
  45
  46                 if (fillable >= 4 && !(off % 4)) {
  47                         __le32 val;
  48
  49                         if (iswrite) {
  50                                 if (copy_from_user(&val, buf, 4))
  51                                         return -EFAULT;
  52
  53                                 iowrite32(le32_to_cpu(val), io + off);
  54                         } else {
  55                                 val = cpu_to_le32(ioread32(io + off));
  56
  57                                 if (copy_to_user(buf, &val, 4))
  58                                         return -EFAULT;
  59                         }
  60
  61                         filled = 4;
  62                 } else if (fillable >= 2 && !(off % 2)) {
  63                         __le16 val;
  64
  65                         if (iswrite) {
  66                                 if (copy_from_user(&val, buf, 2))
  67                                         return -EFAULT;
  68
  69                                 iowrite16(le16_to_cpu(val), io + off);
  70                         } else {
  71                                 val = cpu_to_le16(ioread16(io + off));
  72
  73                                 if (copy_to_user(buf, &val, 2))
  74                                         return -EFAULT;
  75                         }
  76
  77                         filled = 2;
  78                 } else if (fillable) {
  79                         u8 val;
  80
  81                         if (iswrite) {
  82                                 if (copy_from_user(&val, buf, 1))
  83                                         return -EFAULT;
  84
  85                                 iowrite8(val, io + off);
  86                         } else {
  87                                 val = ioread8(io + off);
  88
  89                                 if (copy_to_user(buf, &val, 1))
  90                                         return -EFAULT;
  91                         }
  92
  93                         filled = 1;
  94                 } else {
  95                         /* Fill reads with -1, drop writes */
  96                         filled = min(count, (size_t)(x_end - off));
  97                         if (!iswrite) {
  98                                 u8 val = 0xFF;
  99                                 size_t i;
 100
 101                                 for (i = 0; i < filled; i++)
 102                                         if (copy_to_user(buf + i, &val, 1))
 103                                                 return -EFAULT;
 104                         }
 105                 }
 106
 107                 count -= filled;
 108                 done += filled;
 109                 off += filled;
 110                 buf += filled;
 111         }
 112
 113         return done;
 114 }
 115
 116 ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
 117                         size_t count, loff_t *ppos, bool iswrite)
 118 {
 119         struct pci_dev *pdev = vdev->pdev;
 120         loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
 121         int bar = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
 122         size_t x_start = 0, x_end = 0;
 123         resource_size_t end;
 124         void __iomem *io;
 125         ssize_t done;
 126
 127         if (!pci_resource_start(pdev, bar))
 128                 return -EINVAL;
 129
 130         end = pci_resource_len(pdev, bar);
 131
 132         if (pos >= end)
 133                 return -EINVAL;
 134
 135         count = min(count, (size_t)(end - pos));
 136
 137         if (bar == PCI_ROM_RESOURCE) {
 138                 /*
 139                  * The ROM can fill less space than the BAR, so we start the
 140                  * excluded range at the end of the actual ROM.  This makes
 141                  * filling large ROM BARs much faster.
 142                  */
 143                 io = pci_map_rom(pdev, &x_start);
 144                 if (!io)
 145                         return -ENOMEM;
 146                 x_end = end;
 147         } else if (!vdev->barmap[bar]) {
 148                 int ret;
 149
 150                 ret = pci_request_selected_regions(pdev, 1 << bar, "vfio");
 151                 if (ret)
 152                         return ret;
 153
 154                 io = pci_iomap(pdev, bar, 0);
 155                 if (!io) {
 156                         pci_release_selected_regions(pdev, 1 << bar);
 157                         return -ENOMEM;
 158                 }
 159
 160                 vdev->barmap[bar] = io;
 161         } else
 162                 io = vdev->barmap[bar];
 163
 164         if (bar == vdev->msix_bar) {
 165                 x_start = vdev->msix_offset;
 166                 x_end = vdev->msix_offset + vdev->msix_size;
 167         }
 168
 169         done = do_io_rw(io, buf, pos, count, x_start, x_end, iswrite);
 170
 171         if (done >= 0)
 172                 *ppos += done;
 173
 174         if (bar == PCI_ROM_RESOURCE)
 175                 pci_unmap_rom(pdev, io);
 176
 177         return done;
 178 }
 179
 180 ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char __user *buf,
 181                                size_t count, loff_t *ppos, bool iswrite)
 182 {
 183         int ret;
 184         loff_t off, pos = *ppos & VFIO_PCI_OFFSET_MASK;
 185         void __iomem *iomem = NULL;
 186         unsigned int rsrc;
 187         bool is_ioport;
 188         ssize_t done;
 189
 190         if (!vdev->has_vga)
 191                 return -EINVAL;
 192
 193         switch (pos) {
 194         case 0xa0000 ... 0xbffff:
 195                 count = min(count, (size_t)(0xc0000 - pos));
 196                 iomem = ioremap_nocache(0xa0000, 0xbffff - 0xa0000 + 1);
 197                 off = pos - 0xa0000;
 198                 rsrc = VGA_RSRC_LEGACY_MEM;
 199                 is_ioport = false;
 200                 break;
 201         case 0x3b0 ... 0x3bb:
 202                 count = min(count, (size_t)(0x3bc - pos));
 203                 iomem = ioport_map(0x3b0, 0x3bb - 0x3b0 + 1);
 204                 off = pos - 0x3b0;
 205                 rsrc = VGA_RSRC_LEGACY_IO;
 206                 is_ioport = true;
 207                 break;
 208         case 0x3c0 ... 0x3df:
 209                 count = min(count, (size_t)(0x3e0 - pos));
 210                 iomem = ioport_map(0x3c0, 0x3df - 0x3c0 + 1);
 211                 off = pos - 0x3c0;
 212                 rsrc = VGA_RSRC_LEGACY_IO;
 213                 is_ioport = true;
 214                 break;
 215         default:
 216                 return -EINVAL;
 217         }
 218
 219         if (!iomem)
 220                 return -ENOMEM;
 221
 222         ret = vga_get_interruptible(vdev->pdev, rsrc);
 223         if (ret) {
 224                 is_ioport ? ioport_unmap(iomem) : iounmap(iomem);
 225                 return ret;
 226         }
 227
 228         done = do_io_rw(iomem, buf, off, count, 0, 0, iswrite);
 229
 230         vga_put(vdev->pdev, rsrc);
 231
 232         is_ioport ? ioport_unmap(iomem) : iounmap(iomem);
 233
 234         if (done >= 0)
 235                 *ppos += done;
 236
 237         return done;
 238 }