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linux/drivers/xen/privcmd.c
Juergen Gross c51b3c639e xen: add new hypercall buffer mapping device 
For passing arbitrary data from user land to the Xen hypervisor the
Xen tools today are using mlock()ed buffers. Unfortunately the kernel
might change access rights of such buffers for brief periods of time
e.g. for page migration or compaction, leading to access faults in the
hypervisor, as the hypervisor can't use the locks of the kernel.

In order to solve this problem add a new device node to the Xen privcmd
driver to easily allocate hypercall buffers via mmap(). The memory is
allocated in the kernel and just mapped into user space. Marked as
VM_IO the user mapping will not be subject to page migration et al.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
2018-06-22 08:26:42 +02:00

1029 lines
23 KiB
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/******************************************************************************
* 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/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/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;
domid_t domain;
};
static int mmap_gfn_range(void *data, void *state)
{
struct privcmd_mmap_entry *msg = data;
struct mmap_gfn_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_gfn_range(vma,
msg->va & PAGE_MASK,
msg->mfn, msg->npages,
vma->vm_page_prot,
st->domain, NULL);
if (rc < 0)
return rc;
st->va += msg->npages << PAGE_SHIFT;
return 0;
}
static long privcmd_ioctl_mmap(struct file *file, void __user *udata)
{
struct privcmd_data *data = file->private_data;
struct privcmd_mmap mmapcmd;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int rc;
LIST_HEAD(pagelist);
struct mmap_gfn_state state;
/* We only support privcmd_ioctl_mmap_batch for auto translated. */
if (xen_feature(XENFEAT_auto_translated_physmap))
return -ENOSYS;
if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
return -EFAULT;
/* If restriction is in place, check the domid matches */
if (data->domid != DOMID_INVALID && data->domid != mmapcmd.dom)
return -EPERM;
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) || vma->vm_private_data)
goto out_up;
vma->vm_private_data = PRIV_VMA_LOCKED;
}
state.va = vma->vm_start;
state.vma = vma;
state.domain = mmapcmd.dom;
rc = traverse_pages(mmapcmd.num, sizeof(struct privcmd_mmap_entry),
&pagelist,
mmap_gfn_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;
int index;
/* 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;
int version;
/* User-space gfn array to store errors in the second pass for V1. */
xen_pfn_t __user *user_gfn;
/* User-space int array to store errors in the second pass for V2. */
int __user *user_err;
};
/* auto translated dom0 note: if domU being created is PV, then gfn is
* mfn(addr on bus). If it's auto xlated, then gfn is pfn (input to HAP).
*/
static int mmap_batch_fn(void *data, int nr, void *state)
{
xen_pfn_t *gfnp = data;
struct mmap_batch_state *st = state;
struct vm_area_struct *vma = st->vma;
struct page **pages = vma->vm_private_data;
struct page **cur_pages = NULL;
int ret;
if (xen_feature(XENFEAT_auto_translated_physmap))
cur_pages = &pages[st->index];
BUG_ON(nr < 0);
ret = xen_remap_domain_gfn_array(st->vma, st->va & PAGE_MASK, gfnp, nr,
(int *)gfnp, st->vma->vm_page_prot,
st->domain, cur_pages);
/* Adjust the global_error? */
if (ret != nr) {
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 += XEN_PAGE_SIZE * nr;
st->index += nr / XEN_PFN_PER_PAGE;
return 0;
}
static int mmap_return_error(int err, struct mmap_batch_state *st)
{
int ret;
if (st->version == 1) {
if (err) {
xen_pfn_t gfn;
ret = get_user(gfn, st->user_gfn);
if (ret < 0)
return ret;
/*
* V1 encodes the error codes in the 32bit top
* nibble of the gfn (with its known
* limitations vis-a-vis 64 bit callers).
*/
gfn |= (err == -ENOENT) ?
PRIVCMD_MMAPBATCH_PAGED_ERROR :
PRIVCMD_MMAPBATCH_MFN_ERROR;
return __put_user(gfn, st->user_gfn++);
} else
st->user_gfn++;
} else { /* st->version == 2 */
if (err)
return __put_user(err, st->user_err++);
else
st->user_err++;
}
return 0;
}
static int mmap_return_errors(void *data, int nr, void *state)
{
struct mmap_batch_state *st = state;
int *errs = data;
int i;
int ret;
for (i = 0; i < nr; i++) {
ret = mmap_return_error(errs[i], st);
if (ret < 0)
return ret;
}
return 0;
}
/* Allocate pfns that are then mapped with gfns from foreign domid. Update
* the vma with the page info to use later.
* Returns: 0 if success, otherwise -errno
*/
static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
{
int rc;
struct page **pages;
pages = kcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL);
if (pages == NULL)
return -ENOMEM;
rc = alloc_xenballooned_pages(numpgs, pages);
if (rc != 0) {
pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
numpgs, rc);
kfree(pages);
return -ENOMEM;
}
BUG_ON(vma->vm_private_data != NULL);
vma->vm_private_data = pages;
return 0;
}
static const struct vm_operations_struct privcmd_vm_ops;
static long privcmd_ioctl_mmap_batch(
struct file *file, void __user *udata, int version)
{
struct privcmd_data *data = file->private_data;
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);
struct mmap_batch_state state;
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;
}
/* If restriction is in place, check the domid matches */
if (data->domid != DOMID_INVALID && data->domid != m.dom)
return -EPERM;
nr_pages = DIV_ROUND_UP(m.num, XEN_PFN_PER_PAGE);
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;
}
if (version == 2) {
/* Zero error array now to only copy back actual errors. */
if (clear_user(m.err, sizeof(int) * m.num)) {
ret = -EFAULT;
goto out;
}
}
down_write(&mm->mmap_sem);
vma = find_vma(mm, m.addr);
if (!vma ||
vma->vm_ops != &privcmd_vm_ops) {
ret = -EINVAL;
goto out_unlock;
}
/*
* Caller must either:
*
* Map the whole VMA range, which will also allocate all the
* pages required for the auto_translated_physmap case.
*
* Or
*
* Map unmapped holes left from a previous map attempt (e.g.,
* because those foreign frames were previously paged out).
*/
if (vma->vm_private_data == NULL) {
if (m.addr != vma->vm_start ||
m.addr + (nr_pages << PAGE_SHIFT) != vma->vm_end) {
ret = -EINVAL;
goto out_unlock;
}
if (xen_feature(XENFEAT_auto_translated_physmap)) {
ret = alloc_empty_pages(vma, nr_pages);
if (ret < 0)
goto out_unlock;
} else
vma->vm_private_data = PRIV_VMA_LOCKED;
} else {
if (m.addr < vma->vm_start ||
m.addr + (nr_pages << PAGE_SHIFT) > vma->vm_end) {
ret = -EINVAL;
goto out_unlock;
}
if (privcmd_vma_range_is_mapped(vma, m.addr, nr_pages)) {
ret = -EINVAL;
goto out_unlock;
}
}
state.domain = m.dom;
state.vma = vma;
state.va = m.addr;
state.index = 0;
state.global_error = 0;
state.version = version;
BUILD_BUG_ON(((PAGE_SIZE / sizeof(xen_pfn_t)) % XEN_PFN_PER_PAGE) != 0);
/* mmap_batch_fn guarantees ret == 0 */
BUG_ON(traverse_pages_block(m.num, sizeof(xen_pfn_t),
&pagelist, mmap_batch_fn, &state));
up_write(&mm->mmap_sem);
if (state.global_error) {
/* Write back errors in second pass. */
state.user_gfn = (xen_pfn_t *)m.arr;
state.user_err = m.err;
ret = traverse_pages_block(m.num, sizeof(xen_pfn_t),
&pagelist, mmap_return_errors, &state);
} else
ret = 0;
/* 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:
free_page_list(&pagelist);
return ret;
out_unlock:
up_write(&mm->mmap_sem);
goto out;
}
static int lock_pages(
struct privcmd_dm_op_buf kbufs[], unsigned int num,
struct page *pages[], unsigned int nr_pages)
{
unsigned int i;
for (i = 0; i < num; i++) {
unsigned int requested;
int pinned;
requested = DIV_ROUND_UP(
offset_in_page(kbufs[i].uptr) + kbufs[i].size,
PAGE_SIZE);
if (requested > nr_pages)
return -ENOSPC;
pinned = get_user_pages_fast(
(unsigned long) kbufs[i].uptr,
requested, FOLL_WRITE, pages);
if (pinned < 0)
return pinned;
nr_pages -= pinned;
pages += pinned;
}
return 0;
}
static void unlock_pages(struct page *pages[], unsigned int nr_pages)
{
unsigned int i;
if (!pages)
return;
for (i = 0; i < nr_pages; i++) {
if (pages[i])
put_page(pages[i]);
}
}
static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
{
struct privcmd_data *data = file->private_data;
struct privcmd_dm_op kdata;
struct privcmd_dm_op_buf *kbufs;
unsigned int nr_pages = 0;
struct page **pages = NULL;
struct xen_dm_op_buf *xbufs = NULL;
unsigned int i;
long rc;
if (copy_from_user(&kdata, udata, sizeof(kdata)))
return -EFAULT;
/* If restriction is in place, check the domid matches */
if (data->domid != DOMID_INVALID && data->domid != kdata.dom)
return -EPERM;
if (kdata.num == 0)
return 0;
if (kdata.num > privcmd_dm_op_max_num)
return -E2BIG;
kbufs = kcalloc(kdata.num, sizeof(*kbufs), GFP_KERNEL);
if (!kbufs)
return -ENOMEM;
if (copy_from_user(kbufs, kdata.ubufs,
sizeof(*kbufs) * kdata.num)) {
rc = -EFAULT;
goto out;
}
for (i = 0; i < kdata.num; i++) {
if (kbufs[i].size > privcmd_dm_op_buf_max_size) {
rc = -E2BIG;
goto out;
}
if (!access_ok(VERIFY_WRITE, kbufs[i].uptr,
kbufs[i].size)) {
rc = -EFAULT;
goto out;
}
nr_pages += DIV_ROUND_UP(
offset_in_page(kbufs[i].uptr) + kbufs[i].size,
PAGE_SIZE);
}
pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
if (!pages) {
rc = -ENOMEM;
goto out;
}
xbufs = kcalloc(kdata.num, sizeof(*xbufs), GFP_KERNEL);
if (!xbufs) {
rc = -ENOMEM;
goto out;
}
rc = lock_pages(kbufs, kdata.num, pages, nr_pages);
if (rc)
goto out;
for (i = 0; i < kdata.num; i++) {
set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);
xbufs[i].size = kbufs[i].size;
}
xen_preemptible_hcall_begin();
rc = HYPERVISOR_dm_op(kdata.dom, kdata.num, xbufs);
xen_preemptible_hcall_end();
out:
unlock_pages(pages, nr_pages);
kfree(xbufs);
kfree(pages);
kfree(kbufs);
return rc;
}
static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
{
struct privcmd_data *data = file->private_data;
domid_t dom;
if (copy_from_user(&dom, udata, sizeof(dom)))
return -EFAULT;
/* Set restriction to the specified domain, or check it matches */
if (data->domid == DOMID_INVALID)
data->domid = dom;
else if (data->domid != dom)
return -EINVAL;
return 0;
}
struct remap_pfn {
struct mm_struct *mm;
struct page **pages;
pgprot_t prot;
unsigned long i;
};
static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
void *data)
{
struct remap_pfn *r = data;
struct page *page = r->pages[r->i];
pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
set_pte_at(r->mm, addr, ptep, pte);
r->i++;
return 0;
}
static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
{
struct privcmd_data *data = file->private_data;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct privcmd_mmap_resource kdata;
xen_pfn_t *pfns = NULL;
struct xen_mem_acquire_resource xdata;
int rc;
if (copy_from_user(&kdata, udata, sizeof(kdata)))
return -EFAULT;
/* If restriction is in place, check the domid matches */
if (data->domid != DOMID_INVALID && data->domid != kdata.dom)
return -EPERM;
down_write(&mm->mmap_sem);
vma = find_vma(mm, kdata.addr);
if (!vma || vma->vm_ops != &privcmd_vm_ops) {
rc = -EINVAL;
goto out;
}
pfns = kcalloc(kdata.num, sizeof(*pfns), GFP_KERNEL);
if (!pfns) {
rc = -ENOMEM;
goto out;
}
if (xen_feature(XENFEAT_auto_translated_physmap)) {
unsigned int nr = DIV_ROUND_UP(kdata.num, XEN_PFN_PER_PAGE);
struct page **pages;
unsigned int i;
rc = alloc_empty_pages(vma, nr);
if (rc < 0)
goto out;
pages = vma->vm_private_data;
for (i = 0; i < kdata.num; i++) {
xen_pfn_t pfn =
page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
pfns[i] = pfn + (i % XEN_PFN_PER_PAGE);
}
} else
vma->vm_private_data = PRIV_VMA_LOCKED;
memset(&xdata, 0, sizeof(xdata));
xdata.domid = kdata.dom;
xdata.type = kdata.type;
xdata.id = kdata.id;
xdata.frame = kdata.idx;
xdata.nr_frames = kdata.num;
set_xen_guest_handle(xdata.frame_list, pfns);
xen_preemptible_hcall_begin();
rc = HYPERVISOR_memory_op(XENMEM_acquire_resource, &xdata);
xen_preemptible_hcall_end();
if (rc)
goto out;
if (xen_feature(XENFEAT_auto_translated_physmap)) {
struct remap_pfn r = {
.mm = vma->vm_mm,
.pages = vma->vm_private_data,
.prot = vma->vm_page_prot,
};
rc = apply_to_page_range(r.mm, kdata.addr,
kdata.num << PAGE_SHIFT,
remap_pfn_fn, &r);
} else {
unsigned int domid =
(xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
DOMID_SELF : kdata.dom;
int num;
num = xen_remap_domain_mfn_array(vma,
kdata.addr & PAGE_MASK,
pfns, kdata.num, (int *)pfns,
vma->vm_page_prot,
domid,
vma->vm_private_data);
if (num < 0)
rc = num;
else if (num != kdata.num) {
unsigned int i;
for (i = 0; i < num; i++) {
rc = pfns[i];
if (rc < 0)
break;
}
} else
rc = 0;
}
out:
up_write(&mm->mmap_sem);
kfree(pfns);
return rc;
}
static long privcmd_ioctl(struct file *file,
unsigned int cmd, unsigned long data)
{
int ret = -ENOTTY;
void __user *udata = (void __user *) data;
switch (cmd) {
case IOCTL_PRIVCMD_HYPERCALL:
ret = privcmd_ioctl_hypercall(file, udata);
break;
case IOCTL_PRIVCMD_MMAP:
ret = privcmd_ioctl_mmap(file, udata);
break;
case IOCTL_PRIVCMD_MMAPBATCH:
ret = privcmd_ioctl_mmap_batch(file, udata, 1);
break;
case IOCTL_PRIVCMD_MMAPBATCH_V2:
ret = privcmd_ioctl_mmap_batch(file, udata, 2);
break;
case IOCTL_PRIVCMD_DM_OP:
ret = privcmd_ioctl_dm_op(file, udata);
break;
case IOCTL_PRIVCMD_RESTRICT:
ret = privcmd_ioctl_restrict(file, udata);
break;
case IOCTL_PRIVCMD_MMAP_RESOURCE:
ret = privcmd_ioctl_mmap_resource(file, udata);
break;
default:
break;
}
return ret;
}
static int privcmd_open(struct inode *ino, struct file *file)
{
struct privcmd_data *data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
/* DOMID_INVALID implies no restriction */
data->domid = DOMID_INVALID;
file->private_data = data;
return 0;
}
static int privcmd_release(struct inode *ino, struct file *file)
{
struct privcmd_data *data = file->private_data;
kfree(data);
return 0;
}
static void privcmd_close(struct vm_area_struct *vma)
{
struct page **pages = vma->vm_private_data;
int numpgs = vma_pages(vma);
int numgfns = (vma->vm_end - vma->vm_start) >> XEN_PAGE_SHIFT;
int rc;
if (!xen_feature(XENFEAT_auto_translated_physmap) || !numpgs || !pages)
return;
rc = xen_unmap_domain_gfn_range(vma, numgfns, pages);
if (rc == 0)
free_xenballooned_pages(numpgs, pages);
else
pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
numpgs, rc);
kfree(pages);
}
static vm_fault_t privcmd_fault(struct vm_fault *vmf)
{
printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
vmf->vma, vmf->vma->vm_start, vmf->vma->vm_end,
vmf->pgoff, (void *)vmf->address);
return VM_FAULT_SIGBUS;
}
static const struct vm_operations_struct privcmd_vm_ops = {
.close = privcmd_close,
.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_IO | VM_PFNMAP | VM_DONTCOPY |
VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_ops = &privcmd_vm_ops;
vma->vm_private_data = NULL;
return 0;
}
/*
* For MMAPBATCH*. This allows asserting the singleshot mapping
* on a per pfn/pte basis. Mapping calls that fail with ENOENT
* can be then retried until success.
*/
static int is_mapped_fn(pte_t *pte, struct page *pmd_page,
unsigned long addr, void *data)
{
return pte_none(*pte) ? 0 : -EBUSY;
}
static int privcmd_vma_range_is_mapped(
struct vm_area_struct *vma,
unsigned long addr,
unsigned long nr_pages)
{
return apply_to_page_range(vma->vm_mm, addr, nr_pages << PAGE_SHIFT,
is_mapped_fn, NULL) != 0;
}
const struct file_operations xen_privcmd_fops = {
.owner = THIS_MODULE,
.unlocked_ioctl = privcmd_ioctl,
.open = privcmd_open,
.release = privcmd_release,
.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) {
pr_err("Could not register Xen privcmd device\n");
return err;
}
err = misc_register(&xen_privcmdbuf_dev);
if (err != 0) {
pr_err("Could not register Xen hypercall-buf device\n");
misc_deregister(&privcmd_dev);
return err;
}
return 0;
}
static void __exit privcmd_exit(void)
{
misc_deregister(&privcmd_dev);
misc_deregister(&xen_privcmdbuf_dev);
}
module_init(privcmd_init);
module_exit(privcmd_exit);
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