// 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/eventfd.h>
#include <linux/file.h>
#include <linux/kernel.h>
#include <linux/kstrtox.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/srcu.h>
#include <linux/string.h>
#include <linux/workqueue.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 <linux/notifier.h>
#include <linux/security.h>
#include <linux/virtio_mmio.h>
#include <linux/wait.h>

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

#include <xen/xen.h>
#include <xen/events.h>
#include <xen/privcmd.h>
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>
#include <xen/interface/hvm/dm_op.h>
#include <xen/interface/hvm/ioreq.h>
#include <xen/features.h>
#include <xen/page.h>
#include <xen/xen-ops.h>
#include <xen/balloon.h>
#include <xen/xenbus.h>
#ifdef CONFIG_XEN_ACPI
#include <xen/acpi.h>
#endif

#include "privcmd.h"

MODULE_DESCRIPTION("Xen hypercall passthrough driver");
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");

static bool unrestricted;
module_param(unrestricted, bool, 0);
MODULE_PARM_DESC(unrestricted,
        "Don't restrict hypercalls to target domain if running in a domU");

struct privcmd_data {
        domid_t domid;
};

/* DOMID_INVALID implies no restriction */
static domid_t target_domain = DOMID_INVALID;
static bool restrict_wait;
static DECLARE_WAIT_QUEUE_HEAD(restrict_wait_wq);

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 non-auto-translated. */
        if (!xen_pv_domain())
                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;

        mmap_write_lock(mm);

        {
                struct page *page = list_first_entry(&pagelist,
                                                     struct page, lru);
                struct privcmd_mmap_entry *msg = page_address(page);

                vma = vma_lookup(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:
        mmap_write_unlock(mm);

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_pv_domain())
                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 = kvzalloc_objs(pages[0], numpgs);
        if (pages == NULL)
                return -ENOMEM;

        rc = xen_alloc_unpopulated_pages(numpgs, pages);
        if (rc != 0) {
                pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
                        numpgs, rc);
                kvfree(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(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(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;
                }
        }

        mmap_write_lock(mm);

        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_pv_domain()) {
                        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));

        mmap_write_unlock(mm);

        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:
        mmap_write_unlock(mm);
        goto out;
}

static int lock_pages(
        struct privcmd_dm_op_buf kbufs[], unsigned int num,
        struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
{
        unsigned int i, off = 0;

        for (i = 0; i < num; ) {
                unsigned int requested;
                int page_count;

                requested = DIV_ROUND_UP(
                        offset_in_page(kbufs[i].uptr) + kbufs[i].size,
                        PAGE_SIZE) - off;
                if (requested > nr_pages)
                        return -ENOSPC;

                page_count = pin_user_pages_fast(
                        (unsigned long)kbufs[i].uptr + off * PAGE_SIZE,
                        requested, FOLL_WRITE, pages);
                if (page_count <= 0)
                        return page_count ? : -EFAULT;

                *pinned += page_count;
                nr_pages -= page_count;
                pages += page_count;

                off = (requested == page_count) ? 0 : off + page_count;
                i += !off;
        }

        return 0;
}

static void unlock_pages(struct page *pages[], unsigned int nr_pages)
{
        unpin_user_pages_dirty_lock(pages, nr_pages, true);
}

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;
        unsigned int pinned = 0;

        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 = kzalloc_objs(*kbufs, kdata.num);
        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(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 = kzalloc_objs(*pages, nr_pages);
        if (!pages) {
                rc = -ENOMEM;
                goto out;
        }

        xbufs = kzalloc_objs(*xbufs, kdata.num);
        if (!xbufs) {
                rc = -ENOMEM;
                goto out;
        }

        rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned);
        if (rc < 0)
                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, pinned);
        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;
}

static long privcmd_ioctl_mmap_resource(struct file *file,
                                struct privcmd_mmap_resource __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;

        /* Both fields must be set or unset */
        if (!!kdata.addr != !!kdata.num)
                return -EINVAL;

        xdata.domid = kdata.dom;
        xdata.type = kdata.type;
        xdata.id = kdata.id;

        if (!kdata.addr && !kdata.num) {
                /* Query the size of the resource. */
                rc = HYPERVISOR_memory_op(XENMEM_acquire_resource, &xdata);
                if (rc)
                        return rc;
                return __put_user(xdata.nr_frames, &udata->num);
        }

        mmap_write_lock(mm);

        vma = find_vma(mm, kdata.addr);
        if (!vma || vma->vm_ops != &privcmd_vm_ops) {
                rc = -EINVAL;
                goto out;
        }

        pfns = kzalloc_objs(*pfns, kdata.num, GFP_KERNEL | __GFP_NOWARN);
        if (!pfns) {
                rc = -ENOMEM;
                goto out;
        }

        if (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) && !xen_pv_domain()) {
                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;

        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 (IS_ENABLED(CONFIG_XEN_AUTO_XLATE) && !xen_pv_domain()) {
                rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
        } else {
                unsigned int domid =
                        (xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
                        DOMID_SELF : kdata.dom;
                int num, *errs = (int *)pfns;

                BUILD_BUG_ON(sizeof(*errs) > sizeof(*pfns));
                num = xen_remap_domain_mfn_array(vma,
                                                 kdata.addr & PAGE_MASK,
                                                 pfns, kdata.num, errs,
                                                 vma->vm_page_prot,
                                                 domid);
                if (num < 0)
                        rc = num;
                else if (num != kdata.num) {
                        unsigned int i;

                        for (i = 0; i < num; i++) {
                                rc = errs[i];
                                if (rc < 0)
                                        break;
                        }
                } else
                        rc = 0;
        }

out:
        mmap_write_unlock(mm);
        kfree(pfns);

        return rc;
}

static long privcmd_ioctl_pcidev_get_gsi(struct file *file, void __user *udata)
{
#if defined(CONFIG_XEN_ACPI)
        int rc;
        struct privcmd_pcidev_get_gsi kdata;

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

        rc = xen_acpi_get_gsi_from_sbdf(kdata.sbdf);
        if (rc < 0)
                return rc;

        kdata.gsi = rc;
        if (copy_to_user(udata, &kdata, sizeof(kdata)))
                return -EFAULT;

        return 0;
#else
        return -EINVAL;
#endif
}

#ifdef CONFIG_XEN_PRIVCMD_EVENTFD
/* Irqfd support */
static struct workqueue_struct *irqfd_cleanup_wq;
static DEFINE_SPINLOCK(irqfds_lock);
DEFINE_STATIC_SRCU(irqfds_srcu);
static LIST_HEAD(irqfds_list);

struct privcmd_kernel_irqfd {
        struct xen_dm_op_buf xbufs;
        domid_t dom;
        bool error;
        struct eventfd_ctx *eventfd;
        struct work_struct shutdown;
        wait_queue_entry_t wait;
        struct list_head list;
        poll_table pt;
};

static void irqfd_deactivate(struct privcmd_kernel_irqfd *kirqfd)
{
        lockdep_assert_held(&irqfds_lock);

        list_del_init(&kirqfd->list);
        queue_work(irqfd_cleanup_wq, &kirqfd->shutdown);
}

static void irqfd_shutdown(struct work_struct *work)
{
        struct privcmd_kernel_irqfd *kirqfd =
                container_of(work, struct privcmd_kernel_irqfd, shutdown);
        u64 cnt;

        /* Make sure irqfd has been initialized in assign path */
        synchronize_srcu(&irqfds_srcu);

        eventfd_ctx_remove_wait_queue(kirqfd->eventfd, &kirqfd->wait, &cnt);
        eventfd_ctx_put(kirqfd->eventfd);
        kfree(kirqfd);
}

static void irqfd_inject(struct privcmd_kernel_irqfd *kirqfd)
{
        u64 cnt;
        long rc;

        eventfd_ctx_do_read(kirqfd->eventfd, &cnt);

        xen_preemptible_hcall_begin();
        rc = HYPERVISOR_dm_op(kirqfd->dom, 1, &kirqfd->xbufs);
        xen_preemptible_hcall_end();

        /* Don't repeat the error message for consecutive failures */
        if (rc && !kirqfd->error) {
                pr_err("Failed to configure irq for guest domain: %d\n",
                       kirqfd->dom);
        }

        kirqfd->error = rc;
}

static int
irqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode, int sync, void *key)
{
        struct privcmd_kernel_irqfd *kirqfd =
                container_of(wait, struct privcmd_kernel_irqfd, wait);
        __poll_t flags = key_to_poll(key);

        if (flags & EPOLLIN)
                irqfd_inject(kirqfd);

        if (flags & EPOLLHUP) {
                unsigned long flags;

                spin_lock_irqsave(&irqfds_lock, flags);
                irqfd_deactivate(kirqfd);
                spin_unlock_irqrestore(&irqfds_lock, flags);
        }

        return 0;
}

static void
irqfd_poll_func(struct file *file, wait_queue_head_t *wqh, poll_table *pt)
{
        struct privcmd_kernel_irqfd *kirqfd =
                container_of(pt, struct privcmd_kernel_irqfd, pt);

        add_wait_queue_priority(wqh, &kirqfd->wait);
}

static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
{
        struct privcmd_kernel_irqfd *kirqfd, *tmp;
        unsigned long flags;
        __poll_t events;
        void *dm_op;
        int ret, idx;

        CLASS(fd, f)(irqfd->fd);

        kirqfd = kzalloc(sizeof(*kirqfd) + irqfd->size, GFP_KERNEL);
        if (!kirqfd)
                return -ENOMEM;
        dm_op = kirqfd + 1;

        if (copy_from_user(dm_op, u64_to_user_ptr(irqfd->dm_op), irqfd->size)) {
                ret = -EFAULT;
                goto error_kfree;
        }

        kirqfd->xbufs.size = irqfd->size;
        set_xen_guest_handle(kirqfd->xbufs.h, dm_op);
        kirqfd->dom = irqfd->dom;
        INIT_WORK(&kirqfd->shutdown, irqfd_shutdown);

        if (fd_empty(f)) {
                ret = -EBADF;
                goto error_kfree;
        }

        kirqfd->eventfd = eventfd_ctx_fileget(fd_file(f));
        if (IS_ERR(kirqfd->eventfd)) {
                ret = PTR_ERR(kirqfd->eventfd);
                goto error_kfree;
        }

        /*
         * Install our own custom wake-up handling so we are notified via a
         * callback whenever someone signals the underlying eventfd.
         */
        init_waitqueue_func_entry(&kirqfd->wait, irqfd_wakeup);
        init_poll_funcptr(&kirqfd->pt, irqfd_poll_func);

        spin_lock_irqsave(&irqfds_lock, flags);

        list_for_each_entry(tmp, &irqfds_list, list) {
                if (kirqfd->eventfd == tmp->eventfd) {
                        ret = -EBUSY;
                        spin_unlock_irqrestore(&irqfds_lock, flags);
                        goto error_eventfd;
                }
        }

        idx = srcu_read_lock(&irqfds_srcu);
        list_add_tail(&kirqfd->list, &irqfds_list);
        spin_unlock_irqrestore(&irqfds_lock, flags);

        /*
         * Check if there was an event already pending on the eventfd before we
         * registered, and trigger it as if we didn't miss it.
         */
        events = vfs_poll(fd_file(f), &kirqfd->pt);
        if (events & EPOLLIN)
                irqfd_inject(kirqfd);

        srcu_read_unlock(&irqfds_srcu, idx);
        return 0;

error_eventfd:
        eventfd_ctx_put(kirqfd->eventfd);

error_kfree:
        kfree(kirqfd);
        return ret;
}

static int privcmd_irqfd_deassign(struct privcmd_irqfd *irqfd)
{
        struct privcmd_kernel_irqfd *kirqfd;
        struct eventfd_ctx *eventfd;
        unsigned long flags;

        eventfd = eventfd_ctx_fdget(irqfd->fd);
        if (IS_ERR(eventfd))
                return PTR_ERR(eventfd);

        spin_lock_irqsave(&irqfds_lock, flags);

        list_for_each_entry(kirqfd, &irqfds_list, list) {
                if (kirqfd->eventfd == eventfd) {
                        irqfd_deactivate(kirqfd);
                        break;
                }
        }

        spin_unlock_irqrestore(&irqfds_lock, flags);

        eventfd_ctx_put(eventfd);

        /*
         * Block until we know all outstanding shutdown jobs have completed so
         * that we guarantee there will not be any more interrupts once this
         * deassign function returns.
         */
        flush_workqueue(irqfd_cleanup_wq);

        return 0;
}

static long privcmd_ioctl_irqfd(struct file *file, void __user *udata)
{
        struct privcmd_data *data = file->private_data;
        struct privcmd_irqfd irqfd;

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

        /* No other flags should be set */
        if (irqfd.flags & ~PRIVCMD_IRQFD_FLAG_DEASSIGN)
                return -EINVAL;

        /* If restriction is in place, check the domid matches */
        if (data->domid != DOMID_INVALID && data->domid != irqfd.dom)
                return -EPERM;

        if (irqfd.flags & PRIVCMD_IRQFD_FLAG_DEASSIGN)
                return privcmd_irqfd_deassign(&irqfd);

        return privcmd_irqfd_assign(&irqfd);
}

static int privcmd_irqfd_init(void)
{
        irqfd_cleanup_wq = alloc_workqueue("privcmd-irqfd-cleanup", WQ_PERCPU,
                                           0);
        if (!irqfd_cleanup_wq)
                return -ENOMEM;

        return 0;
}

static void privcmd_irqfd_exit(void)
{
        struct privcmd_kernel_irqfd *kirqfd, *tmp;
        unsigned long flags;

        spin_lock_irqsave(&irqfds_lock, flags);

        list_for_each_entry_safe(kirqfd, tmp, &irqfds_list, list)
                irqfd_deactivate(kirqfd);

        spin_unlock_irqrestore(&irqfds_lock, flags);

        destroy_workqueue(irqfd_cleanup_wq);
}

/* Ioeventfd Support */
#define QUEUE_NOTIFY_VQ_MASK 0xFFFF

static DEFINE_MUTEX(ioreq_lock);
static LIST_HEAD(ioreq_list);

/* per-eventfd structure */
struct privcmd_kernel_ioeventfd {
        struct eventfd_ctx *eventfd;
        struct list_head list;
        u64 addr;
        unsigned int addr_len;
        unsigned int vq;
};

/* per-guest CPU / port structure */
struct ioreq_port {
        int vcpu;
        unsigned int port;
        struct privcmd_kernel_ioreq *kioreq;
};

/* per-guest structure */
struct privcmd_kernel_ioreq {
        domid_t dom;
        unsigned int vcpus;
        u64 uioreq;
        struct ioreq *ioreq;
        spinlock_t lock; /* Protects ioeventfds list */
        struct list_head ioeventfds;
        struct list_head list;
        struct ioreq_port ports[] __counted_by(vcpus);
};

static irqreturn_t ioeventfd_interrupt(int irq, void *dev_id)
{
        struct ioreq_port *port = dev_id;
        struct privcmd_kernel_ioreq *kioreq = port->kioreq;
        struct ioreq *ioreq = &kioreq->ioreq[port->vcpu];
        struct privcmd_kernel_ioeventfd *kioeventfd;
        unsigned int state = STATE_IOREQ_READY;

        if (ioreq->state != STATE_IOREQ_READY ||
            ioreq->type != IOREQ_TYPE_COPY || ioreq->dir != IOREQ_WRITE)
                return IRQ_NONE;

        /*
         * We need a barrier, smp_mb(), here to ensure reads are finished before
         * `state` is updated. Since the lock implementation ensures that
         * appropriate barrier will be added anyway, we can avoid adding
         * explicit barrier here.
         *
         * Ideally we don't need to update `state` within the locks, but we do
         * that here to avoid adding explicit barrier.
         */

        spin_lock(&kioreq->lock);
        ioreq->state = STATE_IOREQ_INPROCESS;

        list_for_each_entry(kioeventfd, &kioreq->ioeventfds, list) {
                if (ioreq->addr == kioeventfd->addr + VIRTIO_MMIO_QUEUE_NOTIFY &&
                    ioreq->size == kioeventfd->addr_len &&
                    (ioreq->data & QUEUE_NOTIFY_VQ_MASK) == kioeventfd->vq) {
                        eventfd_signal(kioeventfd->eventfd);
                        state = STATE_IORESP_READY;
                        break;
                }
        }
        spin_unlock(&kioreq->lock);

        /*
         * We need a barrier, smp_mb(), here to ensure writes are finished
         * before `state` is updated. Since the lock implementation ensures that
         * appropriate barrier will be added anyway, we can avoid adding
         * explicit barrier here.
         */

        ioreq->state = state;

        if (state == STATE_IORESP_READY) {
                notify_remote_via_evtchn(port->port);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static void ioreq_free(struct privcmd_kernel_ioreq *kioreq)
{
        struct ioreq_port *ports = kioreq->ports;
        int i;

        lockdep_assert_held(&ioreq_lock);

        list_del(&kioreq->list);

        for (i = kioreq->vcpus - 1; i >= 0; i--)
                unbind_from_irqhandler(irq_from_evtchn(ports[i].port), &ports[i]);

        kfree(kioreq);
}

static
struct privcmd_kernel_ioreq *alloc_ioreq(struct privcmd_ioeventfd *ioeventfd)
{
        struct privcmd_kernel_ioreq *kioreq;
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        struct page **pages;
        unsigned int *ports;
        int ret, size, i;

        lockdep_assert_held(&ioreq_lock);

        size = struct_size(kioreq, ports, ioeventfd->vcpus);
        kioreq = kzalloc(size, GFP_KERNEL);
        if (!kioreq)
                return ERR_PTR(-ENOMEM);

        kioreq->dom = ioeventfd->dom;
        kioreq->vcpus = ioeventfd->vcpus;
        kioreq->uioreq = ioeventfd->ioreq;
        spin_lock_init(&kioreq->lock);
        INIT_LIST_HEAD(&kioreq->ioeventfds);

        /* The memory for ioreq server must have been mapped earlier */
        mmap_write_lock(mm);
        vma = find_vma(mm, (unsigned long)ioeventfd->ioreq);
        if (!vma) {
                pr_err("Failed to find vma for ioreq page!\n");
                mmap_write_unlock(mm);
                ret = -EFAULT;
                goto error_kfree;
        }

        pages = vma->vm_private_data;
        kioreq->ioreq = (struct ioreq *)(page_to_virt(pages[0]));
        mmap_write_unlock(mm);

        ports = memdup_array_user(u64_to_user_ptr(ioeventfd->ports),
                                  kioreq->vcpus, sizeof(*ports));
        if (IS_ERR(ports)) {
                ret = PTR_ERR(ports);
                goto error_kfree;
        }

        for (i = 0; i < kioreq->vcpus; i++) {
                kioreq->ports[i].vcpu = i;
                kioreq->ports[i].port = ports[i];
                kioreq->ports[i].kioreq = kioreq;

                ret = bind_evtchn_to_irqhandler_lateeoi(ports[i],
                                ioeventfd_interrupt, IRQF_SHARED, "ioeventfd",
                                &kioreq->ports[i]);
                if (ret < 0)
                        goto error_unbind;
        }

        kfree(ports);

        list_add_tail(&kioreq->list, &ioreq_list);

        return kioreq;

error_unbind:
        while (--i >= 0)
                unbind_from_irqhandler(irq_from_evtchn(ports[i]), &kioreq->ports[i]);

        kfree(ports);
error_kfree:
        kfree(kioreq);
        return ERR_PTR(ret);
}

static struct privcmd_kernel_ioreq *
get_ioreq(struct privcmd_ioeventfd *ioeventfd, struct eventfd_ctx *eventfd)
{
        struct privcmd_kernel_ioreq *kioreq;
        unsigned long flags;

        list_for_each_entry(kioreq, &ioreq_list, list) {
                struct privcmd_kernel_ioeventfd *kioeventfd;

                /*
                 * kioreq fields can be accessed here without a lock as they are
                 * never updated after being added to the ioreq_list.
                 */
                if (kioreq->uioreq != ioeventfd->ioreq) {
                        continue;
                } else if (kioreq->dom != ioeventfd->dom ||
                           kioreq->vcpus != ioeventfd->vcpus) {
                        pr_err("Invalid ioeventfd configuration mismatch, dom (%u vs %u), vcpus (%u vs %u)\n",
                               kioreq->dom, ioeventfd->dom, kioreq->vcpus,
                               ioeventfd->vcpus);
                        return ERR_PTR(-EINVAL);
                }

                /* Look for a duplicate eventfd for the same guest */
                spin_lock_irqsave(&kioreq->lock, flags);
                list_for_each_entry(kioeventfd, &kioreq->ioeventfds, list) {
                        if (eventfd == kioeventfd->eventfd) {
                                spin_unlock_irqrestore(&kioreq->lock, flags);
                                return ERR_PTR(-EBUSY);
                        }
                }
                spin_unlock_irqrestore(&kioreq->lock, flags);

                return kioreq;
        }

        /* Matching kioreq isn't found, allocate a new one */
        return alloc_ioreq(ioeventfd);
}

static void ioeventfd_free(struct privcmd_kernel_ioeventfd *kioeventfd)
{
        list_del(&kioeventfd->list);
        eventfd_ctx_put(kioeventfd->eventfd);
        kfree(kioeventfd);
}

static int privcmd_ioeventfd_assign(struct privcmd_ioeventfd *ioeventfd)
{
        struct privcmd_kernel_ioeventfd *kioeventfd;
        struct privcmd_kernel_ioreq *kioreq;
        unsigned long flags;
        int ret;

        /* Check for range overflow */
        if (ioeventfd->addr + ioeventfd->addr_len < ioeventfd->addr)
                return -EINVAL;

        /* Vhost requires us to support length 1, 2, 4, and 8 */
        if (!(ioeventfd->addr_len == 1 || ioeventfd->addr_len == 2 ||
              ioeventfd->addr_len == 4 || ioeventfd->addr_len == 8))
                return -EINVAL;

        /* 4096 vcpus limit enough ? */
        if (!ioeventfd->vcpus || ioeventfd->vcpus > 4096)
                return -EINVAL;

        kioeventfd = kzalloc_obj(*kioeventfd);
        if (!kioeventfd)
                return -ENOMEM;

        kioeventfd->eventfd = eventfd_ctx_fdget(ioeventfd->event_fd);
        if (IS_ERR(kioeventfd->eventfd)) {
                ret = PTR_ERR(kioeventfd->eventfd);
                goto error_kfree;
        }

        kioeventfd->addr = ioeventfd->addr;
        kioeventfd->addr_len = ioeventfd->addr_len;
        kioeventfd->vq = ioeventfd->vq;

        mutex_lock(&ioreq_lock);
        kioreq = get_ioreq(ioeventfd, kioeventfd->eventfd);
        if (IS_ERR(kioreq)) {
                mutex_unlock(&ioreq_lock);
                ret = PTR_ERR(kioreq);
                goto error_eventfd;
        }

        spin_lock_irqsave(&kioreq->lock, flags);
        list_add_tail(&kioeventfd->list, &kioreq->ioeventfds);
        spin_unlock_irqrestore(&kioreq->lock, flags);

        mutex_unlock(&ioreq_lock);

        return 0;

error_eventfd:
        eventfd_ctx_put(kioeventfd->eventfd);

error_kfree:
        kfree(kioeventfd);
        return ret;
}

static int privcmd_ioeventfd_deassign(struct privcmd_ioeventfd *ioeventfd)
{
        struct privcmd_kernel_ioreq *kioreq, *tkioreq;
        struct eventfd_ctx *eventfd;
        unsigned long flags;
        int ret = 0;

        eventfd = eventfd_ctx_fdget(ioeventfd->event_fd);
        if (IS_ERR(eventfd))
                return PTR_ERR(eventfd);

        mutex_lock(&ioreq_lock);
        list_for_each_entry_safe(kioreq, tkioreq, &ioreq_list, list) {
                struct privcmd_kernel_ioeventfd *kioeventfd, *tmp;
                /*
                 * kioreq fields can be accessed here without a lock as they are
                 * never updated after being added to the ioreq_list.
                 */
                if (kioreq->dom != ioeventfd->dom ||
                    kioreq->uioreq != ioeventfd->ioreq ||
                    kioreq->vcpus != ioeventfd->vcpus)
                        continue;

                spin_lock_irqsave(&kioreq->lock, flags);
                list_for_each_entry_safe(kioeventfd, tmp, &kioreq->ioeventfds, list) {
                        if (eventfd == kioeventfd->eventfd) {
                                ioeventfd_free(kioeventfd);
                                spin_unlock_irqrestore(&kioreq->lock, flags);

                                if (list_empty(&kioreq->ioeventfds))
                                        ioreq_free(kioreq);
                                goto unlock;
                        }
                }
                spin_unlock_irqrestore(&kioreq->lock, flags);
                break;
        }

        pr_err("Ioeventfd isn't already assigned, dom: %u, addr: %llu\n",
               ioeventfd->dom, ioeventfd->addr);
        ret = -ENODEV;

unlock:
        mutex_unlock(&ioreq_lock);
        eventfd_ctx_put(eventfd);

        return ret;
}

static long privcmd_ioctl_ioeventfd(struct file *file, void __user *udata)
{
        struct privcmd_data *data = file->private_data;
        struct privcmd_ioeventfd ioeventfd;

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

        /* No other flags should be set */
        if (ioeventfd.flags & ~PRIVCMD_IOEVENTFD_FLAG_DEASSIGN)
                return -EINVAL;

        /* If restriction is in place, check the domid matches */
        if (data->domid != DOMID_INVALID && data->domid != ioeventfd.dom)
                return -EPERM;

        if (ioeventfd.flags & PRIVCMD_IOEVENTFD_FLAG_DEASSIGN)
                return privcmd_ioeventfd_deassign(&ioeventfd);

        return privcmd_ioeventfd_assign(&ioeventfd);
}

static void privcmd_ioeventfd_exit(void)
{
        struct privcmd_kernel_ioreq *kioreq, *tmp;
        unsigned long flags;

        mutex_lock(&ioreq_lock);
        list_for_each_entry_safe(kioreq, tmp, &ioreq_list, list) {
                struct privcmd_kernel_ioeventfd *kioeventfd, *tmp;

                spin_lock_irqsave(&kioreq->lock, flags);
                list_for_each_entry_safe(kioeventfd, tmp, &kioreq->ioeventfds, list)
                        ioeventfd_free(kioeventfd);
                spin_unlock_irqrestore(&kioreq->lock, flags);

                ioreq_free(kioreq);
        }
        mutex_unlock(&ioreq_lock);
}
#else
static inline long privcmd_ioctl_irqfd(struct file *file, void __user *udata)
{
        return -EOPNOTSUPP;
}

static inline int privcmd_irqfd_init(void)
{
        return 0;
}

static inline void privcmd_irqfd_exit(void)
{
}

static inline long privcmd_ioctl_ioeventfd(struct file *file, void __user *udata)
{
        return -EOPNOTSUPP;
}

static inline void privcmd_ioeventfd_exit(void)
{
}
#endif /* CONFIG_XEN_PRIVCMD_EVENTFD */

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;

        case IOCTL_PRIVCMD_IRQFD:
                ret = privcmd_ioctl_irqfd(file, udata);
                break;

        case IOCTL_PRIVCMD_IOEVENTFD:
                ret = privcmd_ioctl_ioeventfd(file, udata);
                break;

        case IOCTL_PRIVCMD_PCIDEV_GET_GSI:
                ret = privcmd_ioctl_pcidev_get_gsi(file, udata);
                break;

        default:
                break;
        }

        return ret;
}

static int privcmd_open(struct inode *ino, struct file *file)
{
        struct privcmd_data *data;

        if (wait_event_interruptible(restrict_wait_wq, !restrict_wait) < 0)
                return -EINTR;

        data = kzalloc_obj(*data);
        if (!data)
                return -ENOMEM;

        data->domid = target_domain;

        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_pv_domain() || !numpgs || !pages)
                return;

        rc = xen_unmap_domain_gfn_range(vma, numgfns, pages);
        if (rc == 0)
                xen_free_unpopulated_pages(numpgs, pages);
        else
                pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
                        numpgs, rc);
        kvfree(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 */
        vm_flags_set(vma, 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, unsigned long addr, void *data)
{
        return pte_none(ptep_get(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_restrict(struct notifier_block *notifier,
                         unsigned long event,
                         void *data)
{
        char *target;
        unsigned int domid;

        /* Default to an guaranteed unused domain-id. */
        target_domain = DOMID_IDLE;

        target = xenbus_read(XBT_NIL, "target", "", NULL);
        if (IS_ERR(target) || kstrtouint(target, 10, &domid)) {
                pr_err("No target domain found, blocking all hypercalls\n");
                goto out;
        }

        target_domain = domid;

 out:
        if (!IS_ERR(target))
                kfree(target);

        restrict_wait = false;
        wake_up_all(&restrict_wait_wq);

        return NOTIFY_DONE;
}

static struct notifier_block xenstore_notifier = {
        .notifier_call = init_restrict,
};

static void __init restrict_driver(void)
{
        if (unrestricted) {
                if (security_locked_down(LOCKDOWN_XEN_USER_ACTIONS))
                        pr_warn("Kernel is locked down, parameter \"unrestricted\" ignored\n");
                else
                        return;
        }

        restrict_wait = true;

        register_xenstore_notifier(&xenstore_notifier);
}

static int __init privcmd_init(void)
{
        int err;

        if (!xen_domain())
                return -ENODEV;

        if (!xen_initial_domain())
                restrict_driver();

        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");
                goto err_privcmdbuf;
        }

        err = privcmd_irqfd_init();
        if (err != 0) {
                pr_err("irqfd init failed\n");
                goto err_irqfd;
        }

        return 0;

err_irqfd:
        misc_deregister(&xen_privcmdbuf_dev);
err_privcmdbuf:
        misc_deregister(&privcmd_dev);
        return err;
}

static void __exit privcmd_exit(void)
{
        if (!xen_initial_domain())
                unregister_xenstore_notifier(&xenstore_notifier);

        privcmd_ioeventfd_exit();
        privcmd_irqfd_exit();
        misc_deregister(&privcmd_dev);
        misc_deregister(&xen_privcmdbuf_dev);
}

module_init(privcmd_init);
module_exit(privcmd_exit);