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
 14static DEFINE_MUTEX(list_lock);
 15static struct page *page_list;
 16static unsigned int list_count;
 17
 18static 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	res->name = "Xen scratch";
 31	res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 32
 33	ret = allocate_resource(&iomem_resource, res,
 34				alloc_pages * PAGE_SIZE, 0, -1,
 35				PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
 36	if (ret < 0) {
 37		pr_err("Cannot allocate new IOMEM resource\n");
 38		goto err_resource;
 39	}
 40
 41	pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
 42	if (!pgmap) {
 43		ret = -ENOMEM;
 44		goto err_pgmap;
 45	}
 46
 47	pgmap->type = MEMORY_DEVICE_GENERIC;
 48	pgmap->range = (struct range) {
 49		.start = res->start,
 50		.end = res->end,
 51	};
 52	pgmap->nr_range = 1;
 53	pgmap->owner = res;
 54
 55#ifdef CONFIG_XEN_HAVE_PVMMU
 56        /*
 57         * memremap will build page tables for the new memory so
 58         * the p2m must contain invalid entries so the correct
 59         * non-present PTEs will be written.
 60         *
 61         * If a failure occurs, the original (identity) p2m entries
 62         * are not restored since this region is now known not to
 63         * conflict with any devices.
 64         */
 65	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
 66		xen_pfn_t pfn = PFN_DOWN(res->start);
 67
 68		for (i = 0; i < alloc_pages; i++) {
 69			if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
 70				pr_warn("set_phys_to_machine() failed, no memory added\n");
 71				ret = -ENOMEM;
 72				goto err_memremap;
 73			}
 74                }
 75	}
 76#endif
 77
 78	vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
 79	if (IS_ERR(vaddr)) {
 80		pr_err("Cannot remap memory range\n");
 81		ret = PTR_ERR(vaddr);
 82		goto err_memremap;
 83	}
 84
 85	for (i = 0; i < alloc_pages; i++) {
 86		struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
 87
 88		BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));
 89		pg->zone_device_data = page_list;
 90		page_list = pg;
 91		list_count++;
 92	}
 93
 94	return 0;
 95
 96err_memremap:
 97	kfree(pgmap);
 98err_pgmap:
 99	release_resource(res);
100err_resource:
101	kfree(res);
102	return ret;
103}
104
105/**
106 * xen_alloc_unpopulated_pages - alloc unpopulated pages
107 * @nr_pages: Number of pages
108 * @pages: pages returned
109 * @return 0 on success, error otherwise
110 */
111int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
112{
113	unsigned int i;
114	int ret = 0;
115
116	mutex_lock(&list_lock);
117	if (list_count < nr_pages) {
118		ret = fill_list(nr_pages - list_count);
119		if (ret)
120			goto out;
121	}
122
123	for (i = 0; i < nr_pages; i++) {
124		struct page *pg = page_list;
125
126		BUG_ON(!pg);
127		page_list = pg->zone_device_data;
128		list_count--;
129		pages[i] = pg;
130
131#ifdef CONFIG_XEN_HAVE_PVMMU
132		if (!xen_feature(XENFEAT_auto_translated_physmap)) {
133			ret = xen_alloc_p2m_entry(page_to_pfn(pg));
134			if (ret < 0) {
135				unsigned int j;
136
137				for (j = 0; j <= i; j++) {
138					pages[j]->zone_device_data = page_list;
139					page_list = pages[j];
140					list_count++;
141				}
142				goto out;
143			}
144		}
145#endif
146	}
147
148out:
149	mutex_unlock(&list_lock);
150	return ret;
151}
152EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
153
154/**
155 * xen_free_unpopulated_pages - return unpopulated pages
156 * @nr_pages: Number of pages
157 * @pages: pages to return
158 */
159void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
160{
161	unsigned int i;
162
163	mutex_lock(&list_lock);
164	for (i = 0; i < nr_pages; i++) {
165		pages[i]->zone_device_data = page_list;
166		page_list = pages[i];
167		list_count++;
168	}
169	mutex_unlock(&list_lock);
170}
171EXPORT_SYMBOL(xen_free_unpopulated_pages);
172
173#ifdef CONFIG_XEN_PV
174static int __init init(void)
175{
176	unsigned int i;
177
178	if (!xen_domain())
179		return -ENODEV;
180
181	if (!xen_pv_domain())
182		return 0;
183
184	/*
185	 * Initialize with pages from the extra memory regions (see
186	 * arch/x86/xen/setup.c).
187	 */
188	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
189		unsigned int j;
190
191		for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {
192			struct page *pg =
193				pfn_to_page(xen_extra_mem[i].start_pfn + j);
194
195			pg->zone_device_data = page_list;
196			page_list = pg;
197			list_count++;
198		}
199	}
200
201	return 0;
202}
203subsys_initcall(init);
204#endif