path: root/drivers/xen/privcmd.c

// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
 * privcmd.c
 *
 * Interface to privileged domain-0 commands.
 *
 * Copyright (c) 2002-2004, K A Fraser, B Dragovic
 */

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

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/uaccess.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/seq_file.h>
#include <linux/miscdevice.h>
#include <linux/moduleparam.h>

#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include <xen/xen.h>
#include <xen/privcmd.h>
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>
#include <xen/interface/hvm/dm_op.h>
#include <xen/features.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/balloon.h>

#include "privcmd.h"

MODULE_LICENSE("GPL");

#define PRIV_VMA_LOCKED ((void *)1)

static unsigned int privcmd_dm_op_max_num = 16;
module_param_named(dm_op_max_nr_bufs, privcmd_dm_op_max_num, uint, 0644);
MODULE_PARM_DESC(dm_op_max_nr_bufs,
		 "Maximum number of buffers per dm_op hypercall");

static unsigned int privcmd_dm_op_buf_max_size = 4096;
module_param_named(dm_op_buf_max_size, privcmd_dm_op_buf_max_size, uint,
		   0644);
MODULE_PARM_DESC(dm_op_buf_max_size,
		 "Maximum size of a dm_op hypercall buffer");

struct privcmd_data {
	domid_t domid;
};

static int privcmd_vma_range_is_mapped(
               struct vm_area_struct *vma,
               unsigned long addr,
               unsigned long nr_pages);

static long privcmd_ioctl_hypercall(struct file *file, void __user *udata)
{
	struct privcmd_data *data = file->private_data;
	struct privcmd_hypercall hypercall;
	long ret;

	/* Disallow arbitrary hypercalls if restricted */
	if (data->domid != DOMID_INVALID)
		return -EPERM;

	if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
		return -EFAULT;

	xen_preemptible_hcall_begin();
	ret = privcmd_call(hypercall.op,
			   hypercall.arg[0], hypercall.arg[1],
			   hypercall.arg[2], hypercall.arg[3],
			   hypercall.arg[4]);
	xen_preemptible_hcall_end();

	return ret;
}

static void free_page_list(struct list_head *pages)
{
	struct page *p, *n;

	list_for_each_entry_safe(p, n, pages, lru)
		__free_page(p);

	INIT_LIST_HEAD(pages);
}

/*
 * Given an array of items in userspace, return a list of pages
 * containing the data.  If copying fails, either because of memory
 * allocation failure or a problem reading user memory, return an
 * error code; its up to the caller to dispose of any partial list.
 */
static int gather_array(struct list_head *pagelist,
			unsigned nelem, size_t size,
			const void __user *data)
{
	unsigned pageidx;
	void *pagedata;
	int ret;

	if (size > PAGE_SIZE)
		return 0;

	pageidx = PAGE_SIZE;
	pagedata = NULL;	/* quiet, gcc */
	while (nelem--) {
		if (pageidx > PAGE_SIZE-size) {
			struct page *page = alloc_page(GFP_KERNEL);

			ret = -ENOMEM;
			if (page == NULL)
				goto fail;

			pagedata = page_address(page);

			list_add_tail(&page->lru, pagelist);
			pageidx = 0;
		}

		ret = -EFAULT;
		if (copy_from_user(pagedata + pageidx, data, size))
			goto fail;

		data += size;
		pageidx += size;
	}

	ret = 0;

fail:
	return ret;
}

/*
 * Call function "fn" on each element of the array fragmented
 * over a list of pages.
 */
static int traverse_pages(unsigned nelem, size_t size,
			  struct list_head *pos,
			  int (*fn)(void *data, void *state),
			  void *state)
{
	void *pagedata;
	unsigned pageidx;
	int ret = 0;

	BUG_ON(size > PAGE_SIZE);

	pageidx = PAGE_SIZE;
	pagedata = NULL;	/* hush, gcc */

	while (nelem--) {
		if (pageidx > PAGE_SIZE-size) {
			struct page *page;
			pos = pos->next;
			page = list_entry(pos, struct page, lru);
			pagedata = page_address(page);
			pageidx = 0;
		}

		ret = (*fn)(pagedata + pageidx, state);
		if (ret)
			break;
		pageidx += size;
	}

	return ret;
}

/*
 * Similar to traverse_pages, but use each page as a "block" of
 * data to be processed as one unit.
 */
static int traverse_pages_block(unsigned nelem, size_t size,
				struct list_head *pos,
				int (*fn)(void *data, int nr, void *state),
				void *state)
{
	void *pagedata;
	int ret = 0;

	BUG_ON(size > PAGE_SIZE);

	while (nelem) {
		int nr = (PAGE_SIZE/size);
		struct page *page;
		if (nr > nelem)
			nr = nelem;
		pos = pos->next;
		page = list_entry(pos, struct page, lru);
		pagedata = page_address(page);
		ret = (*fn)(pagedata, nr, state);
		if (ret)
			break;
		nelem -= nr;
	}

	return ret;
}

struct mmap_gfn_state {
	unsigned long va;
	struct vm_area_struct *vma</