arch/x86/xen/grant-table.c

   1 // SPDX-License-Identifier: GPL-2.0 OR MIT
   2 /******************************************************************************
   3  * grant_table.c
   4  * x86 specific part
   5  *
   6  * Granting foreign access to our memory reservation.
   7  *
   8  * Copyright (c) 2005-2006, Christopher Clark
   9  * Copyright (c) 2004-2005, K A Fraser
  10  * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
  11  *                    VA Linux Systems Japan. Split out x86 specific part.
  12  */
  13
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/slab.h>
  17 #include <linux/vmalloc.h>
  18
  19 #include <xen/interface/xen.h>
  20 #include <xen/page.h>
  21 #include <xen/grant_table.h>
  22 #include <xen/xen.h>
  23
  24
  25 static struct gnttab_vm_area {
  26         struct vm_struct *area;
  27         pte_t **ptes;
  28         int idx;
  29 } gnttab_shared_vm_area, gnttab_status_vm_area;
  30
  31 int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
  32                            unsigned long max_nr_gframes,
  33                            void **__shared)
  34 {
  35         void *shared = *__shared;
  36         unsigned long addr;
  37         unsigned long i;
  38
  39         if (shared == NULL)
  40                 *__shared = shared = gnttab_shared_vm_area.area->addr;
  41
  42         addr = (unsigned long)shared;
  43
  44         for (i = 0; i < nr_gframes; i++) {
  45                 set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
  46                            mfn_pte(frames[i], PAGE_KERNEL));
  47                 addr += PAGE_SIZE;
  48         }
  49
  50         return 0;
  51 }
  52
  53 int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
  54                            unsigned long max_nr_gframes,
  55                            grant_status_t **__shared)
  56 {
  57         grant_status_t *shared = *__shared;
  58         unsigned long addr;
  59         unsigned long i;
  60
  61         if (shared == NULL)
  62                 *__shared = shared = gnttab_status_vm_area.area->addr;
  63
  64         addr = (unsigned long)shared;
  65
  66         for (i = 0; i < nr_gframes; i++) {
  67                 set_pte_at(&init_mm, addr, gnttab_status_vm_area.ptes[i],
  68                            mfn_pte(frames[i], PAGE_KERNEL));
  69                 addr += PAGE_SIZE;
  70         }
  71
  72         return 0;
  73 }
  74
  75 void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
  76 {
  77         pte_t **ptes;
  78         unsigned long addr;
  79         unsigned long i;
  80
  81         if (shared == gnttab_status_vm_area.area->addr)
  82                 ptes = gnttab_status_vm_area.ptes;
  83         else
  84                 ptes = gnttab_shared_vm_area.ptes;
  85
  86         addr = (unsigned long)shared;
  87
  88         for (i = 0; i < nr_gframes; i++) {
  89                 set_pte_at(&init_mm, addr, ptes[i], __pte(0));
  90                 addr += PAGE_SIZE;
  91         }
  92 }
  93
  94 static int gnttab_apply(pte_t *pte, unsigned long addr, void *data)
  95 {
  96         struct gnttab_vm_area *area = data;
  97
  98         area->ptes[area->idx++] = pte;
  99         return 0;
 100 }
 101
 102 static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames)
 103 {
 104         area->ptes = kmalloc_array(nr_frames, sizeof(*area->ptes), GFP_KERNEL);
 105         if (area->ptes == NULL)
 106                 return -ENOMEM;
 107         area->area = get_vm_area(PAGE_SIZE * nr_frames, VM_IOREMAP);
 108         if (!area->area)
 109                 goto out_free_ptes;
 110         if (apply_to_page_range(&init_mm, (unsigned long)area->area->addr,
 111                         PAGE_SIZE * nr_frames, gnttab_apply, area))
 112                 goto out_free_vm_area;
 113         return 0;
 114 out_free_vm_area:
 115         free_vm_area(area->area);
 116 out_free_ptes:
 117         kfree(area->ptes);
 118         return -ENOMEM;
 119 }
 120
 121 static void arch_gnttab_vfree(struct gnttab_vm_area *area)
 122 {
 123         free_vm_area(area->area);
 124         kfree(area->ptes);
 125 }
 126
 127 int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
 128 {
 129         int ret;
 130
 131         if (!xen_pv_domain())
 132                 return 0;
 133
 134         ret = arch_gnttab_valloc(&gnttab_shared_vm_area, nr_shared);
 135         if (ret < 0)
 136                 return ret;
 137
 138         /*
 139          * Always allocate the space for the status frames in case
 140          * we're migrated to a host with V2 support.
 141          */
 142         ret = arch_gnttab_valloc(&gnttab_status_vm_area, nr_status);
 143         if (ret < 0)
 144                 goto err;
 145
 146         return 0;
 147 err:
 148         arch_gnttab_vfree(&gnttab_shared_vm_area);
 149         return -ENOMEM;
 150 }
 151
 152 #ifdef CONFIG_XEN_PVH
 153 #include <xen/events.h>
 154 #include <xen/xen-ops.h>
 155 static int __init xen_pvh_gnttab_setup(void)
 156 {
 157         if (!xen_pvh_domain())
 158                 return -ENODEV;
 159
 160         xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames();
 161
 162         return xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,
 163                                              &xen_auto_xlat_grant_frames.vaddr,
 164                                              xen_auto_xlat_grant_frames.count);
 165 }
 166 /* Call it _before_ __gnttab_init as we need to initialize the
 167  * xen_auto_xlat_grant_frames first. */
 168 core_initcall(xen_pvh_gnttab_setup);
 169 #endif