drivers/xen/unpopulated-alloc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/errno.h>
   3 #include <linux/gfp.h>
   4 #include <linux/kernel.h>
   5 #include <linux/mm.h>
   6 #include <linux/memremap.h>
   7 #include <linux/slab.h>
   8
   9 #include <asm/page.h>
  10
  11 #include <xen/page.h>
  12 #include <xen/xen.h>
  13
  14 static DEFINE_MUTEX(list_lock);
  15 static LIST_HEAD(page_list);
  16 static unsigned int list_count;
  17
  18 static int fill_list(unsigned int nr_pages)
  19 {
  20         struct dev_pagemap *pgmap;
  21         struct resource *res;
  22         void *vaddr;
  23         unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
  24         int ret = -ENOMEM;
  25
  26         res = kzalloc(sizeof(*res), GFP_KERNEL);
  27         if (!res)
  28                 return -ENOMEM;
  29
  30         pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
  31         if (!pgmap)
  32                 goto err_pgmap;
  33
  34         pgmap->type = MEMORY_DEVICE_GENERIC;
  35         res->name = "Xen scratch";
  36         res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
  37
  38         ret = allocate_resource(&iomem_resource, res,
  39                                 alloc_pages * PAGE_SIZE, 0, -1,
  40                                 PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
  41         if (ret < 0) {
  42                 pr_err("Cannot allocate new IOMEM resource\n");
  43                 goto err_resource;
  44         }
  45
  46         pgmap->range = (struct range) {
  47                 .start = res->start,
  48                 .end = res->end,
  49         };
  50         pgmap->owner = res;
  51
  52 #ifdef CONFIG_XEN_HAVE_PVMMU
  53         /*
  54          * memremap will build page tables for the new memory so
  55          * the p2m must contain invalid entries so the correct
  56          * non-present PTEs will be written.
  57          *
  58          * If a failure occurs, the original (identity) p2m entries
  59          * are not restored since this region is now known not to
  60          * conflict with any devices.
  61          */
  62         if (!xen_feature(XENFEAT_auto_translated_physmap)) {
  63                 xen_pfn_t pfn = PFN_DOWN(res->start);
  64
  65                 for (i = 0; i < alloc_pages; i++) {
  66                         if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
  67                                 pr_warn("set_phys_to_machine() failed, no memory added\n");
  68                                 ret = -ENOMEM;
  69                                 goto err_memremap;
  70                         }
  71                 }
  72         }
  73 #endif
  74
  75         vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
  76         if (IS_ERR(vaddr)) {
  77                 pr_err("Cannot remap memory range\n");
  78                 ret = PTR_ERR(vaddr);
  79                 goto err_memremap;
  80         }
  81
  82         for (i = 0; i < alloc_pages; i++) {
  83                 struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
  84
  85                 BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));
  86                 list_add(&pg->lru, &page_list);
  87                 list_count++;
  88         }
  89
  90         return 0;
  91
  92 err_memremap:
  93         release_resource(res);
  94 err_resource:
  95         kfree(pgmap);
  96 err_pgmap:
  97         kfree(res);
  98         return ret;
  99 }
 100
 101 /**
 102  * xen_alloc_unpopulated_pages - alloc unpopulated pages
 103  * @nr_pages: Number of pages
 104  * @pages: pages returned
 105  * @return 0 on success, error otherwise
 106  */
 107 int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
 108 {
 109         unsigned int i;
 110         int ret = 0;
 111
 112         mutex_lock(&list_lock);
 113         if (list_count < nr_pages) {
 114                 ret = fill_list(nr_pages - list_count);
 115                 if (ret)
 116                         goto out;
 117         }
 118
 119         for (i = 0; i < nr_pages; i++) {
 120                 struct page *pg = list_first_entry_or_null(&page_list,
 121                                                            struct page,
 122                                                            lru);
 123
 124                 BUG_ON(!pg);
 125                 list_del(&pg->lru);
 126                 list_count--;
 127                 pages[i] = pg;
 128
 129 #ifdef CONFIG_XEN_HAVE_PVMMU
 130                 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
 131                         ret = xen_alloc_p2m_entry(page_to_pfn(pg));
 132                         if (ret < 0) {
 133                                 unsigned int j;
 134
 135                                 for (j = 0; j <= i; j++) {
 136                                         list_add(&pages[j]->lru, &page_list);
 137                                         list_count++;
 138                                 }
 139                                 goto out;
 140                         }
 141                 }
 142 #endif
 143         }
 144
 145 out:
 146         mutex_unlock(&list_lock);
 147         return ret;
 148 }
 149 EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
 150
 151 /**
 152  * xen_free_unpopulated_pages - return unpopulated pages
 153  * @nr_pages: Number of pages
 154  * @pages: pages to return
 155  */
 156 void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
 157 {
 158         unsigned int i;
 159
 160         mutex_lock(&list_lock);
 161         for (i = 0; i < nr_pages; i++) {
 162                 list_add(&pages[i]->lru, &page_list);
 163                 list_count++;
 164         }
 165         mutex_unlock(&list_lock);
 166 }
 167 EXPORT_SYMBOL(xen_free_unpopulated_pages);
 168
 169 #ifdef CONFIG_XEN_PV
 170 static int __init init(void)
 171 {
 172         unsigned int i;
 173
 174         if (!xen_domain())
 175                 return -ENODEV;
 176
 177         if (!xen_pv_domain())
 178                 return 0;
 179
 180         /*
 181          * Initialize with pages from the extra memory regions (see
 182          * arch/x86/xen/setup.c).
 183          */
 184         for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
 185                 unsigned int j;
 186
 187                 for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {
 188                         struct page *pg =
 189                                 pfn_to_page(xen_extra_mem[i].start_pfn + j);
 190
 191                         list_add(&pg->lru, &page_list);
 192                         list_count++;
 193                 }
 194         }
 195
 196         return 0;
 197 }
 198 subsys_initcall(init);
 199 #endif