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