drivers/vfio/pci/vfio_pci_igd.c

/*
 * VFIO PCI Intel Graphics support
 *
 * Copyright (C) 2016 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.
 *
 * Register a device specific region through which to provide read-only
 * access to the Intel IGD opregion.  The register defining the opregion
 * address is also virtualized to prevent user modification.
 */

#include <linux/io.h>
#include <linux/pci.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>

#include "vfio_pci_private.h"

#define OPREGION_SIGNATURE	"IntelGraphicsMem"
#define OPREGION_SIZE		(8 * 1024)
#define OPREGION_PCI_ADDR	0xfc

static size_t vfio_pci_igd_rw(struct vfio_pci_device *vdev, char __user *buf,
			      size_t count, loff_t *ppos, bool iswrite)
{
	unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
	void *base = vdev->region[i].data;
	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;

	if (pos >= vdev->region[i].size || iswrite)
		return -EINVAL;

	count = min(count, (size_t)(vdev->region[i].size - pos));

	if (copy_to_user(buf, base + pos, count))
		return -EFAULT;

	*ppos += count;

	return count;
}

static void vfio_pci_igd_release(struct vfio_pci_device *vdev,
				 struct vfio_pci_region *region)
{
	memunmap(region->data);
}

static const struct vfio_pci_regops vfio_pci_igd_regops = {
	.rw		= vfio_pci_igd_rw,
	.release	= vfio_pci_igd_release,
};

int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
{
	__le32 *dwordp = (__le32 *)(vdev->vconfig + OPREGION_PCI_ADDR);
	u32 addr, size;
	void *base;
	int ret;

	ret = pci_read_config_dword(vdev->pdev, OPREGION_PCI_ADDR, &addr);
	if (ret)
		return ret;

	if (!addr || !(~addr))
		return -ENODEV;

	base = memremap(addr, OPREGION_SIZE, MEMREMAP_WB);
	if (!base)
		return -ENOMEM;

	if (memcmp(base, OPREGION_SIGNATURE, 16)) {
		memunmap(base);
		return -EINVAL;
	}

	size = le32_to_cpu(*(__le32 *)(base + 16));
	if (!size) {
		memunmap(base);
		return -EINVAL;
	}

	size *= 1024; /* In KB */

	if (size != OPREGION_SIZE) {
		memunmap(base);
		base = memremap(addr, size, MEMREMAP_WB);
		if (!base)
			return -ENOMEM;
	}

	ret = vfio_pci_register_dev_region(vdev,
		PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
		VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION,
		&vfio_pci_igd_regops, size, VFIO_REGION_INFO_FLAG_READ, base);
	if (ret) {
		memunmap(base);
		return ret;
	}

	/* Fill vconfig with the hw value and virtualize register */
	*dwordp = cpu_to_le32(addr);
	memset(vdev->pci_config_map + OPREGION_PCI_ADDR,
	       PCI_CAP_ID_INVALID_VIRT, 4);

	return ret;
}