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// SPDX-License-Identifier: GPL-2.0
#include <linux/errno.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/memremap.h>
#include <linux/slab.h>
#include <asm/page.h>
#include <xen/page.h>
#include <xen/xen.h>
static DEFINE_MUTEX(list_lock);
static LIST_HEAD(page_list);
static unsigned int list_count;
static int fill_list(unsigned int nr_pages)
{
struct dev_pagemap *pgmap;
void *vaddr;
unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
int ret;
pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
if (!pgmap)
return -ENOMEM;
pgmap->type = MEMORY_DEVICE_GENERIC;
pgmap->res.name = "Xen scratch";
pgmap->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
ret = allocate_resource(&iomem_resource, &pgmap->res,
alloc_pages * PAGE_SIZE, 0, -1,
PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
if (ret < 0) {
pr_err("Cannot allocate new IOMEM resource\n");
kfree(pgmap);
return ret;
}
#ifdef CONFIG_XEN_HAVE_PVMMU
/*
* memremap will build page tables for the new memory so
* the p2m must contain invalid entries so the correct
* non-present PTEs will be written.
*
* If a failure occurs, the original (identity) p2m entries
* are not restored since this region is now known not to
* conflict with any devices.
*/
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
xen_pfn_t pfn = PFN_DOWN(pgmap->res.start);
for (i = 0; i < alloc_pages; i++) {
if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
pr_warn("set_phys_to_machine() failed, no memory added\n");
release_resource(&pgmap->res);
kfree(pgmap);
return -ENOMEM;
}
}
}
#endif
vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
if (IS_ERR(vaddr)) {
pr_err("Cannot remap memory range\n");
release_resource(&pgmap->res);
kfree(pgmap);
return PTR_ERR(vaddr);
}
for (i = 0; i < alloc_pages; i++) {
struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));
list_add(&pg->lru, &page_list);
list_count++;
}
return 0;
}
/**
* xen_alloc_unpopulated_pages - alloc unpopulated pages
* @nr_pages: Number of pages
* @pages: pages returned
* @return 0 on success, error otherwise
*/
int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
{
unsigned int i;
int ret = 0;
mutex_lock(&list_lock);
if (list_count < nr_pages) {
ret = fill_list(nr_pages - list_count);
if (ret)
goto out;
}
for (i = 0; i < nr_pages; i++) {
struct page *pg = list_first_entry_or_null(&page_list,
struct page,
lru);
BUG_ON(!pg);
list_del(&pg->lru);
list_count--;
pages[i] = pg;
#ifdef CONFIG_XEN_HAVE_PVMMU
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
ret = xen_alloc_p2m_entry(page_to_pfn(pg));
if (ret < 0) {
unsigned int j;
for (j = 0; j <= i; j++) {
list_add(&pages[j]->lru, &page_list);
list_count++;
}
goto out;
}
}
#endif
}
out:
mutex_unlock(&list_lock);
return ret;
}
EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
/**
* xen_free_unpopulated_pages - return unpopulated pages
* @nr_pages: Number of pages
* @pages: pages to return
*/
void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
{
unsigned int i;
mutex_lock(&list_lock);
for (i = 0; i < nr_pages; i++) {
list_add(&pages[i]->lru, &page_list);
list_count++;
}
mutex_unlock(&list_lock);
}
EXPORT_SYMBOL(xen_free_unpopulated_pages);
#ifdef CONFIG_XEN_PV
static int __init init(void)
{
unsigned int i;
if (!xen_domain())
return -ENODEV;
if (!xen_pv_domain())
return 0;
/*
* Initialize with pages from the extra memory regions (see
* arch/x86/xen/setup.c).
*/
for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
unsigned int j;
for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {
struct page *pg =
pfn_to_page(xen_extra_mem[i].start_pfn + j);
list_add(&pg->lru, &page_list);
list_count++;
}
}
return 0;
}
subsys_initcall(init);
#endif
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