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/*
* VFIO PCI I/O Port & MMIO access
*
* Copyright (C) 2012 Red Hat, Inc. All rights reserved.
* Author: Alex Williamson <alex.williamson@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Derived from original vfio:
* Copyright 2010 Cisco Systems, Inc. All rights reserved.
* Author: Tom Lyon, pugs@cisco.com
*/
#include <linux/fs.h>
#include <linux/pci.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include "vfio_pci_private.h"
/*
* Read or write from an __iomem region (MMIO or I/O port) with an excluded
* range which is inaccessible. The excluded range drops writes and fills
* reads with -1. This is intended for handling MSI-X vector tables and
* leftover space for ROM BARs.
*/
static ssize_t do_io_rw(void __iomem *io, char __user *buf,
loff_t off, size_t count, size_t x_start,
size_t x_end, bool iswrite)
{
ssize_t done = 0;
while (count) {
size_t fillable, filled;
if (off < x_start)
fillable = min(count, (size_t)(x_start - off));
else if (off >= x_end)
fillable = count;
else
fillable = 0;
if (fillable >= 4 && !(off % 4)) {
__le32 val;
if (iswrite) {
if (copy_from_user(&val, buf, 4))
return -EFAULT;
iowrite32(le32_to_cpu(val), io + off);
} else {
val = cpu_to_le32(ioread32(io + off));
if (copy_to_user(buf, &val, 4))
return -EFAULT;
}
filled = 4;
} else if (fillable >= 2 && !(off % 2)) {
__le16 val;
if (iswrite) {
if (copy_from_user(&val, buf, 2))
return -EFAULT;
iowrite16(le16_to_cpu(val), io + off);
} else {
val = cpu_to_le16(ioread16(io + off));
if (copy_to_user(buf, &val, 2))
return -EFAULT;
}
filled = 2;
} else if (fillable) {
u8 val;
if (iswrite) {
if (copy_from_user(&val, buf, 1))
return -EFAULT;
iowrite8(val, io + off);
} else {
val = ioread8(io + off);
if (copy_to_user(buf, &val, 1))
return -EFAULT;
}
filled = 1;
} else {
/* Fill reads with -1, drop writes */
filled = min(count, (size_t)(x_end - off));
if (!iswrite) {
u8 val = 0xFF;
size_t i;
for (i = 0; i < filled; i++)
if (copy_to_user(buf + i, &val, 1))
return -EFAULT;
}
}
count -= filled;
done += filled;
off += filled;
buf += filled;
}
return done;
}
ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
size_t count, loff_t *ppos, bool iswrite)
{
struct pci_dev *pdev = vdev->pdev;
loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
int bar = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
size_t x_start = 0, x_end = 0;
resource_size_t end;
void __iomem *io;
ssize_t done;
if (!pci_resource_start(pdev, bar))
return -EINVAL;
end = pci_resource_len(pdev, bar);
if (pos >= end)
return -EINVAL;
count = min(count, (size_t)(end - pos));
if (bar == PCI_ROM_RESOURCE) {
/*
* The ROM can fill less space than the BAR, so we start the
* excluded range at the end of the actual ROM. This makes
* filling large ROM BARs much faster.
*/
io = pci_map_rom(pdev, &x_start);
if (!io)
return -ENOMEM;
x_end = end;
} else if (!vdev->barmap[bar]) {
int ret;
ret = pci_request_selected_regions(pdev, 1 << bar, "vfio");
if (ret)
return ret;
io = pci_iomap(pdev, bar, 0);
if (!io) {
pci_release_selected_regions(pdev, 1 << bar);
return -ENOMEM;
}
vdev->barmap[bar] = io;
} else
io = vdev->barmap[bar];
if (bar == vdev->msix_bar) {
x_start = vdev->msix_offset;
x_end = vdev->msix_offset + vdev->msix_size;
}
done = do_io_rw(io, buf, pos, count, x_start, x_end, iswrite);
if (done >= 0)
*ppos += done;
if (bar == PCI_ROM_RESOURCE)
pci_unmap_rom(pdev, io);
return done;
}
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