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 struct page *page_list;
16 static unsigned int list_count;
17
fill_list(unsigned int nr_pages)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->nr_range = 1;
51 pgmap->owner = res;
52
53 #ifdef CONFIG_XEN_HAVE_PVMMU
54 /*
55 * memremap will build page tables for the new memory so
56 * the p2m must contain invalid entries so the correct
57 * non-present PTEs will be written.
58 *
59 * If a failure occurs, the original (identity) p2m entries
60 * are not restored since this region is now known not to
61 * conflict with any devices.
62 */
63 if (!xen_feature(XENFEAT_auto_translated_physmap)) {
64 xen_pfn_t pfn = PFN_DOWN(res->start);
65
66 for (i = 0; i < alloc_pages; i++) {
67 if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
68 pr_warn("set_phys_to_machine() failed, no memory added\n");
69 ret = -ENOMEM;
70 goto err_memremap;
71 }
72 }
73 }
74 #endif
75
76 vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
77 if (IS_ERR(vaddr)) {
78 pr_err("Cannot remap memory range\n");
79 ret = PTR_ERR(vaddr);
80 goto err_memremap;
81 }
82
83 for (i = 0; i < alloc_pages; i++) {
84 struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
85
86 BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));
87 pg->zone_device_data = page_list;
88 page_list = pg;
89 list_count++;
90 }
91
92 return 0;
93
94 err_memremap:
95 release_resource(res);
96 err_resource:
97 kfree(pgmap);
98 err_pgmap:
99 kfree(res);
100 return ret;
101 }
102
103 /**
104 * xen_alloc_unpopulated_pages - alloc unpopulated pages
105 * @nr_pages: Number of pages
106 * @pages: pages returned
107 * @return 0 on success, error otherwise
108 */
xen_alloc_unpopulated_pages(unsigned int nr_pages,struct page ** pages)109 int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
110 {
111 unsigned int i;
112 int ret = 0;
113
114 mutex_lock(&list_lock);
115 if (list_count < nr_pages) {
116 ret = fill_list(nr_pages - list_count);
117 if (ret)
118 goto out;
119 }
120
121 for (i = 0; i < nr_pages; i++) {
122 struct page *pg = page_list;
123
124 BUG_ON(!pg);
125 page_list = pg->zone_device_data;
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 pages[j]->zone_device_data = page_list;
137 page_list = pages[j];
138 list_count++;
139 }
140 goto out;
141 }
142 }
143 #endif
144 }
145
146 out:
147 mutex_unlock(&list_lock);
148 return ret;
149 }
150 EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
151
152 /**
153 * xen_free_unpopulated_pages - return unpopulated pages
154 * @nr_pages: Number of pages
155 * @pages: pages to return
156 */
xen_free_unpopulated_pages(unsigned int nr_pages,struct page ** pages)157 void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
158 {
159 unsigned int i;
160
161 mutex_lock(&list_lock);
162 for (i = 0; i < nr_pages; i++) {
163 pages[i]->zone_device_data = page_list;
164 page_list = pages[i];
165 list_count++;
166 }
167 mutex_unlock(&list_lock);
168 }
169 EXPORT_SYMBOL(xen_free_unpopulated_pages);
170
171 #ifdef CONFIG_XEN_PV
init(void)172 static int __init init(void)
173 {
174 unsigned int i;
175
176 if (!xen_domain())
177 return -ENODEV;
178
179 if (!xen_pv_domain())
180 return 0;
181
182 /*
183 * Initialize with pages from the extra memory regions (see
184 * arch/x86/xen/setup.c).
185 */
186 for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
187 unsigned int j;
188
189 for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {
190 struct page *pg =
191 pfn_to_page(xen_extra_mem[i].start_pfn + j);
192
193 pg->zone_device_data = page_list;
194 page_list = pg;
195 list_count++;
196 }
197 }
198
199 return 0;
200 }
201 subsys_initcall(init);
202 #endif
203