arch/x86/xen/grant-table.c

   1 /******************************************************************************
   2  * grant_table.c
   3  * x86 specific part
   4  *
   5  * Granting foreign access to our memory reservation.
   6  *
   7  * Copyright (c) 2005-2006, Christopher Clark
   8  * Copyright (c) 2004-2005, K A Fraser
   9  * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
  10  *                    VA Linux Systems Japan. Split out x86 specific part.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License version 2
  14  * as published by the Free Software Foundation; or, when distributed
  15  * separately from the Linux kernel or incorporated into other
  16  * software packages, subject to the following license:
  17  *
  18  * Permission is hereby granted, free of charge, to any person obtaining a copy
  19  * of this source file (the "Software"), to deal in the Software without
  20  * restriction, including without limitation the rights to use, copy, modify,
  21  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  22  * and to permit persons to whom the Software is furnished to do so, subject to
  23  * the following conditions:
  24  *
  25  * The above copyright notice and this permission notice shall be included in
  26  * all copies or substantial portions of the Software.
  27  *
  28  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  29  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  30  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  31  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  32  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  33  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  34  * IN THE SOFTWARE.
  35  */
  36
  37 #include <linux/sched.h>
  38 #include <linux/mm.h>
  39 #include <linux/slab.h>
  40 #include <linux/vmalloc.h>
  41
  42 #include <xen/interface/xen.h>
  43 #include <xen/page.h>
  44 #include <xen/grant_table.h>
  45 #include <xen/xen.h>
  46
  47 #include <asm/pgtable.h>
  48
  49 static struct gnttab_vm_area {
  50         struct vm_struct *area;
  51         pte_t **ptes;
  52 } gnttab_shared_vm_area;
  53
  54 int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
  55                            unsigned long max_nr_gframes,
  56                            void **__shared)
  57 {
  58         void *shared = *__shared;
  59         unsigned long addr;
  60         unsigned long i;
  61
  62         if (shared == NULL)
  63                 *__shared = shared = gnttab_shared_vm_area.area->addr;
  64
  65         addr = (unsigned long)shared;
  66
  67         for (i = 0; i < nr_gframes; i++) {
  68                 set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
  69                            mfn_pte(frames[i], PAGE_KERNEL));
  70                 addr += PAGE_SIZE;
  71         }
  72
  73         return 0;
  74 }
  75
  76 void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
  77 {
  78         unsigned long addr;
  79         unsigned long i;
  80
  81         addr = (unsigned long)shared;
  82
  83         for (i = 0; i < nr_gframes; i++) {
  84                 set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
  85                            __pte(0));
  86                 addr += PAGE_SIZE;
  87         }
  88 }
  89
  90 static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames)
  91 {
  92         area->ptes = kmalloc(sizeof(pte_t *) * nr_frames, GFP_KERNEL);
  93         if (area->ptes == NULL)
  94                 return -ENOMEM;
  95
  96         area->area = alloc_vm_area(PAGE_SIZE * nr_frames, area->ptes);
  97         if (area->area == NULL) {
  98                 kfree(area->ptes);
  99                 return -ENOMEM;
 100         }
 101
 102         return 0;
 103 }
 104
 105 int arch_gnttab_init(unsigned long nr_shared)
 106 {
 107         if (!xen_pv_domain())
 108                 return 0;
 109
 110         return arch_gnttab_valloc(&gnttab_shared_vm_area, nr_shared);
 111 }
 112
 113 #ifdef CONFIG_XEN_PVH
 114 #include <xen/balloon.h>
 115 #include <xen/events.h>
 116 #include <linux/slab.h>
 117 static int __init xlated_setup_gnttab_pages(void)
 118 {
 119         struct page **pages;
 120         xen_pfn_t *pfns;
 121         int rc;
 122         unsigned int i;
 123         unsigned long nr_grant_frames = gnttab_max_grant_frames();
 124
 125         BUG_ON(nr_grant_frames == 0);
 126         pages = kcalloc(nr_grant_frames, sizeof(pages[0]), GFP_KERNEL);
 127         if (!pages)
 128                 return -ENOMEM;
 129
 130         pfns = kcalloc(nr_grant_frames, sizeof(pfns[0]), GFP_KERNEL);
 131         if (!pfns) {
 132                 kfree(pages);
 133                 return -ENOMEM;
 134         }
 135         rc = alloc_xenballooned_pages(nr_grant_frames, pages, 0 /* lowmem */);
 136         if (rc) {
 137                 pr_warn("%s Couldn't balloon alloc %ld pfns rc:%d\n", __func__,
 138                         nr_grant_frames, rc);
 139                 kfree(pages);
 140                 kfree(pfns);
 141                 return rc;
 142         }
 143         for (i = 0; i < nr_grant_frames; i++)
 144                 pfns[i] = page_to_pfn(pages[i]);
 145
 146         rc = arch_gnttab_map_shared(pfns, nr_grant_frames, nr_grant_frames,
 147                                     &xen_auto_xlat_grant_frames.vaddr);
 148
 149         if (rc) {
 150                 pr_warn("%s Couldn't map %ld pfns rc:%d\n", __func__,
 151                         nr_grant_frames, rc);
 152                 free_xenballooned_pages(nr_grant_frames, pages);
 153                 kfree(pages);
 154                 kfree(pfns);
 155                 return rc;
 156         }
 157         kfree(pages);
 158
 159         xen_auto_xlat_grant_frames.pfn = pfns;
 160         xen_auto_xlat_grant_frames.count = nr_grant_frames;
 161
 162         return 0;
 163 }
 164
 165 static int __init xen_pvh_gnttab_setup(void)
 166 {
 167         if (!xen_pvh_domain())
 168                 return -ENODEV;
 169
 170         return xlated_setup_gnttab_pages();
 171 }
 172 /* Call it _before_ __gnttab_init as we need to initialize the
 173  * xen_auto_xlat_grant_frames first. */
 174 core_initcall(xen_pvh_gnttab_setup);
 175 #endif