path: root/drivers/xen/gntdev.c

/******************************************************************************
 * gntdev.c
 *
 * Device for accessing (in user-space) pages that have been granted by other
 * domains.
 *
 * Copyright (c) 2006-2007, D G Murray.
 *           (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
 *           (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#undef DEBUG

#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/refcount.h>
#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
#include <linux/of_device.h>
#endif

#include <xen/xen.h>
#include <xen/grant_table.h>
#include <xen/balloon.h>
#include <xen/gntdev.h>
#include <xen/events.h>
#include <xen/page.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include "gntdev-common.h"
#ifdef CONFIG_XEN_GNTDEV_DMABUF
#include "gntdev-dmabuf.h"
#endif

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
	      "Gerd Hoffmann <kraxel@redhat.com>");
MODULE_DESCRIPTION("User-space granted page access driver");

static int limit = 1024*1024;
module_param(limit, int, 0644);
MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
		"the gntdev device");

static atomic_t pages_mapped = ATOMIC_INIT(0);

static int use_ptemod;
#define populate_freeable_maps use_ptemod

static int unmap_grant_pages(struct gntdev_grant_map *map,
			     int offset, int pages);

static struct miscdevice gntdev_miscdev;

/* ------------------------------------------------------------------ */

bool gntdev_account_mapped_pages(int count)
{
	return atomic_add_return(count, &pages_mapped) > limit;
}

static void gntdev_print_maps(struct gntdev_priv *priv,
			      char *text, int text_index)
{
#ifdef DEBUG
	struct gntdev_grant_map *map;

	pr_debug("%s: maps list (priv %p)\n", __func__, priv);
	list_for_each_entry(map, &priv->maps, next)
		pr_debug("  index %2d, count %2d %s\n",
		       map->index, map->count,
		       map->index == text_index && text ? text : "");
#endif
}

static void gntdev_free_map(struct gntdev_grant_map *map)
{
	if (map == NULL)
		return;

#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
	if (map->dma_vaddr) {
		struct gnttab_dma_alloc_args args;

		args.dev = map->dma_dev;
		args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
		args.nr_pages = map->count;
		args.pages = map->pages;
		args.frames = map->frames;
		args.vaddr = map->dma_vaddr;
		args.dev_bus_addr = map->dma_bus_addr;

		gnttab_dma_free_pages(&args);
	} else
#endif
	if (map->pages)
		gnttab_free_pages(map->count, map->pages);

#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
	kfree(map->frames);
#endif
	kfree(map->pages);
	kfree(map->grants);
	kfree(map->map_ops);
	kfree(map->unmap_ops);
	kfree(map->kmap_ops);
	kfree(map->kunmap_ops);
	kfree(map);
}

struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
					  int dma_flags)
{
	struct gntdev_grant_map *add;
	int i;

	add = kzalloc