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-rw-r--r--drivers/xen/unpopulated-alloc.c248
1 files changed, 248 insertions, 0 deletions
diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c
new file mode 100644
index 000000000..a39f2d36d
--- /dev/null
+++ b/drivers/xen/unpopulated-alloc.c
@@ -0,0 +1,248 @@
+// 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/balloon.h>
+#include <xen/page.h>
+#include <xen/xen.h>
+
+static DEFINE_MUTEX(list_lock);
+static struct page *page_list;
+static unsigned int list_count;
+
+static struct resource *target_resource;
+
+/*
+ * If arch is not happy with system "iomem_resource" being used for
+ * the region allocation it can provide it's own view by creating specific
+ * Xen resource with unused regions of guest physical address space provided
+ * by the hypervisor.
+ */
+int __weak __init arch_xen_unpopulated_init(struct resource **res)
+{
+ *res = &iomem_resource;
+
+ return 0;
+}
+
+static int fill_list(unsigned int nr_pages)
+{
+ struct dev_pagemap *pgmap;
+ struct resource *res, *tmp_res = NULL;
+ void *vaddr;
+ unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
+ struct range mhp_range;
+ int ret;
+
+ res = kzalloc(sizeof(*res), GFP_KERNEL);
+ if (!res)
+ return -ENOMEM;
+
+ res->name = "Xen scratch";
+ res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+
+ mhp_range = mhp_get_pluggable_range(true);
+
+ ret = allocate_resource(target_resource, res,
+ alloc_pages * PAGE_SIZE, mhp_range.start, mhp_range.end,
+ PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
+ if (ret < 0) {
+ pr_err("Cannot allocate new IOMEM resource\n");
+ goto err_resource;
+ }
+
+ /*
+ * Reserve the region previously allocated from Xen resource to avoid
+ * re-using it by someone else.
+ */
+ if (target_resource != &iomem_resource) {
+ tmp_res = kzalloc(sizeof(*tmp_res), GFP_KERNEL);
+ if (!tmp_res) {
+ ret = -ENOMEM;
+ goto err_insert;
+ }
+
+ tmp_res->name = res->name;
+ tmp_res->start = res->start;
+ tmp_res->end = res->end;
+ tmp_res->flags = res->flags;
+
+ ret = request_resource(&iomem_resource, tmp_res);
+ if (ret < 0) {
+ pr_err("Cannot request resource %pR (%d)\n", tmp_res, ret);
+ kfree(tmp_res);
+ goto err_insert;
+ }
+ }
+
+ pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
+ if (!pgmap) {
+ ret = -ENOMEM;
+ goto err_pgmap;
+ }
+
+ pgmap->type = MEMORY_DEVICE_GENERIC;
+ pgmap->range = (struct range) {
+ .start = res->start,
+ .end = res->end,
+ };
+ pgmap->nr_range = 1;
+ pgmap->owner = res;
+
+#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(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");
+ ret = -ENOMEM;
+ goto err_memremap;
+ }
+ }
+ }
+#endif
+
+ vaddr = memremap_pages(pgmap, NUMA_NO_NODE);
+ if (IS_ERR(vaddr)) {
+ pr_err("Cannot remap memory range\n");
+ ret = PTR_ERR(vaddr);
+ goto err_memremap;
+ }
+
+ for (i = 0; i < alloc_pages; i++) {
+ struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
+
+ pg->zone_device_data = page_list;
+ page_list = pg;
+ list_count++;
+ }
+
+ return 0;
+
+err_memremap:
+ kfree(pgmap);
+err_pgmap:
+ if (tmp_res) {
+ release_resource(tmp_res);
+ kfree(tmp_res);
+ }
+err_insert:
+ release_resource(res);
+err_resource:
+ kfree(res);
+ return ret;
+}
+
+/**
+ * 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;
+
+ /*
+ * Fallback to default behavior if we do not have any suitable resource
+ * to allocate required region from and as the result we won't be able to
+ * construct pages.
+ */
+ if (!target_resource)
+ return xen_alloc_ballooned_pages(nr_pages, pages);
+
+ 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 = page_list;
+
+ BUG_ON(!pg);
+ page_list = pg->zone_device_data;
+ 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++) {
+ pages[j]->zone_device_data = page_list;
+ page_list = pages[j];
+ 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;
+
+ if (!target_resource) {
+ xen_free_ballooned_pages(nr_pages, pages);
+ return;
+ }
+
+ mutex_lock(&list_lock);
+ for (i = 0; i < nr_pages; i++) {
+ pages[i]->zone_device_data = page_list;
+ page_list = pages[i];
+ list_count++;
+ }
+ mutex_unlock(&list_lock);
+}
+EXPORT_SYMBOL(xen_free_unpopulated_pages);
+
+static int __init unpopulated_init(void)
+{
+ int ret;
+
+ if (!xen_domain())
+ return -ENODEV;
+
+ ret = arch_xen_unpopulated_init(&target_resource);
+ if (ret) {
+ pr_err("xen:unpopulated: Cannot initialize target resource\n");
+ target_resource = NULL;
+ }
+
+ return ret;
+}
+early_initcall(unpopulated_init);