linux/drivers/xen/privcmd.c

505 lines
11 KiB
C

/******************************************************************************
* privcmd.c
*
* Interface to privileged domain-0 commands.
*
* Copyright (c) 2002-2004, K A Fraser, B Dragovic
*/
#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 <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/tlb.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/features.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include "privcmd.h"
MODULE_LICENSE("GPL");
#ifndef HAVE_ARCH_PRIVCMD_MMAP
static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma);
#endif
static long privcmd_ioctl_hypercall(void __user *udata)
{
struct privcmd_hypercall hypercall;
long ret;
if (copy_from_user(&hypercall, udata, sizeof(hypercall)))
return -EFAULT;
ret = privcmd_call(hypercall.op,
hypercall.arg[0], hypercall.arg[1],
hypercall.arg[2], hypercall.arg[3],
hypercall.arg[4]);
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;
}
struct mmap_mfn_state {
unsigned long va;
struct vm_area_struct *vma;
domid_t domain;
};
static int mmap_mfn_range(void *data, void *state)
{
struct privcmd_mmap_entry *msg = data;
struct mmap_mfn_state *st = state;
struct vm_area_struct *vma = st->vma;
int rc;
/* Do not allow range to wrap the address space. */
if ((msg->npages > (LONG_MAX >> PAGE_SHIFT)) ||
((unsigned long)(msg->npages << PAGE_SHIFT) >= -st->va))
return -EINVAL;
/* Range chunks must be contiguous in va space. */
if ((msg->va != st->va) ||
((msg->va+(msg->npages<<PAGE_SHIFT)) > vma->vm_end))
return -EINVAL;
rc = xen_remap_domain_mfn_range(vma,
msg->va & PAGE_MASK,
msg->mfn, msg->npages,
vma->vm_page_prot,
st->domain);
if (rc < 0)
return rc;
st->va += msg->npages << PAGE_SHIFT;
return 0;
}
static long privcmd_ioctl_mmap(void __user *udata)
{
struct privcmd_mmap mmapcmd;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int rc;
LIST_HEAD(pagelist);
struct mmap_mfn_state state;
if (!xen_initial_domain())
return -EPERM;
if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
return -EFAULT;
rc = gather_array(&pagelist,
mmapcmd.num, sizeof(struct privcmd_mmap_entry),
mmapcmd.entry);
if (rc || list_empty(&pagelist))
goto out;
down_write(&mm->mmap_sem);
{
struct page *page = list_first_entry(&pagelist,
struct page, lru);
struct privcmd_mmap_entry *msg = page_address(page);
vma = find_vma(mm, msg->va);
rc = -EINVAL;
if (!vma || (msg->va != vma->vm_start) ||
!privcmd_enforce_singleshot_mapping(vma))
goto out_up;
}
state.va = vma->vm_start;
state.vma = vma;
state.domain = mmapcmd.dom;
rc = traverse_pages(mmapcmd.num, sizeof(struct privcmd_mmap_entry),
&pagelist,
mmap_mfn_range, &state);
out_up:
up_write(&mm->mmap_sem);
out:
free_page_list(&pagelist);
return rc;
}
struct mmap_batch_state {
domid_t domain;
unsigned long va;
struct vm_area_struct *vma;
/* A tristate:
* 0 for no errors
* 1 if at least one error has happened (and no
* -ENOENT errors have happened)
* -ENOENT if at least 1 -ENOENT has happened.
*/
int global_error;
/* An array for individual errors */
int *err;
/* User-space mfn array to store errors in the second pass for V1. */
xen_pfn_t __user *user_mfn;
};
static int mmap_batch_fn(void *data, void *state)
{
xen_pfn_t *mfnp = data;
struct mmap_batch_state *st = state;
int ret;
ret = xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
st->vma->vm_page_prot, st->domain);
/* Store error code for second pass. */
*(st->err++) = ret;
/* And see if it affects the global_error. */
if (ret < 0) {
if (ret == -ENOENT)
st->global_error = -ENOENT;
else {
/* Record that at least one error has happened. */
if (st->global_error == 0)
st->global_error = 1;
}
}
st->va += PAGE_SIZE;
return 0;
}
static int mmap_return_errors_v1(void *data, void *state)
{
xen_pfn_t *mfnp = data;
struct mmap_batch_state *st = state;
int err = *(st->err++);
/*
* V1 encodes the error codes in the 32bit top nibble of the
* mfn (with its known limitations vis-a-vis 64 bit callers).
*/
*mfnp |= (err == -ENOENT) ?
PRIVCMD_MMAPBATCH_PAGED_ERROR :
PRIVCMD_MMAPBATCH_MFN_ERROR;
return __put_user(*mfnp, st->user_mfn++);
}
static struct vm_operations_struct privcmd_vm_ops;
static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
{
int ret;
struct privcmd_mmapbatch_v2 m;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long nr_pages;
LIST_HEAD(pagelist);
int *err_array = NULL;
struct mmap_batch_state state;
if (!xen_initial_domain())
return -EPERM;
switch (version) {
case 1:
if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
return -EFAULT;
/* Returns per-frame error in m.arr. */
m.err = NULL;
if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr)))
return -EFAULT;
break;
case 2:
if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch_v2)))
return -EFAULT;
/* Returns per-frame error code in m.err. */
if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err))))
return -EFAULT;
break;
default:
return -EINVAL;
}
nr_pages = m.num;
if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT)))
return -EINVAL;
ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), m.arr);
if (ret)
goto out;
if (list_empty(&pagelist)) {
ret = -EINVAL;
goto out;
}
err_array = kcalloc(m.num, sizeof(int), GFP_KERNEL);
if (err_array == NULL) {
ret = -ENOMEM;
goto out;
}
down_write(&mm->mmap_sem);
vma = find_vma(mm, m.addr);
ret = -EINVAL;
if (!vma ||
vma->vm_ops != &privcmd_vm_ops ||
(m.addr != vma->vm_start) ||
((m.addr + (nr_pages << PAGE_SHIFT)) != vma->vm_end) ||
!privcmd_enforce_singleshot_mapping(vma)) {
up_write(&mm->mmap_sem);
goto out;
}
state.domain = m.dom;
state.vma = vma;
state.va = m.addr;
state.global_error = 0;
state.err = err_array;
/* mmap_batch_fn guarantees ret == 0 */
BUG_ON(traverse_pages(m.num, sizeof(xen_pfn_t),
&pagelist, mmap_batch_fn, &state));
up_write(&mm->mmap_sem);
if (state.global_error && (version == 1)) {
/* Write back errors in second pass. */
state.user_mfn = (xen_pfn_t *)m.arr;
state.err = err_array;
ret = traverse_pages(m.num, sizeof(xen_pfn_t),
&pagelist, mmap_return_errors_v1, &state);
} else if (version == 2) {
ret = __copy_to_user(m.err, err_array, m.num * sizeof(int));
if (ret)
ret = -EFAULT;
}
/* If we have not had any EFAULT-like global errors then set the global
* error to -ENOENT if necessary. */
if ((ret == 0) && (state.global_error == -ENOENT))
ret = -ENOENT;
out:
kfree(err_array);
free_page_list(&pagelist);
return ret;
}
static long privcmd_ioctl(struct file *file,
unsigned int cmd, unsigned long data)
{
int ret = -ENOSYS;
void __user *udata = (void __user *) data;
switch (cmd) {
case IOCTL_PRIVCMD_HYPERCALL:
ret = privcmd_ioctl_hypercall(udata);
break;
case IOCTL_PRIVCMD_MMAP:
ret = privcmd_ioctl_mmap(udata);
break;
case IOCTL_PRIVCMD_MMAPBATCH:
ret = privcmd_ioctl_mmap_batch(udata, 1);
break;
case IOCTL_PRIVCMD_MMAPBATCH_V2:
ret = privcmd_ioctl_mmap_batch(udata, 2);
break;
default:
ret = -EINVAL;
break;
}
return ret;
}
static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
vma, vma->vm_start, vma->vm_end,
vmf->pgoff, vmf->virtual_address);
return VM_FAULT_SIGBUS;
}
static struct vm_operations_struct privcmd_vm_ops = {
.fault = privcmd_fault
};
static int privcmd_mmap(struct file *file, struct vm_area_struct *vma)
{
/* DONTCOPY is essential for Xen because copy_page_range doesn't know
* how to recreate these mappings */
vma->vm_flags |= VM_RESERVED | VM_IO | VM_DONTCOPY | VM_PFNMAP;
vma->vm_ops = &privcmd_vm_ops;
vma->vm_private_data = NULL;
return 0;
}
static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
{
return (xchg(&vma->vm_private_data, (void *)1) == NULL);
}
const struct file_operations xen_privcmd_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = privcmd_ioctl,
.mmap = privcmd_mmap,
};
EXPORT_SYMBOL_GPL(xen_privcmd_fops);
static struct miscdevice privcmd_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "xen/privcmd",
.fops = &xen_privcmd_fops,
};
static int __init privcmd_init(void)
{
int err;
if (!xen_domain())
return -ENODEV;
err = misc_register(&privcmd_dev);
if (err != 0) {
printk(KERN_ERR "Could not register Xen privcmd device\n");
return err;
}
return 0;
}
static void __exit privcmd_exit(void)
{
misc_deregister(&privcmd_dev);
}
module_init(privcmd_init);
module_exit(privcmd_exit);