Changes RFC -> V2:
- new patch, instead of
"[RFC PATCH 2/2] xen/unpopulated-alloc: Query hypervisor to provide unallocated
space"
Changes V2 -> V3:
- update patch description and comments in code
- modify arch_xen_unpopulated_init() to pass target_resource as an argument
and update default helper to assign iomem_resource to it, also drop
xen_resource as it will be located in arch code in the future
- allocate region from hotpluggable range instead of hardcoded range (0,-1)
in fill_list()
- use %pR specifier in error message
- do not call unpopulated_init() at runtime from
xen_alloc_unpopulated_pages(),
drop an extra helper and call arch_xen_unpopulated_init() directly from
__init()
- include linux/ioport.h instead of forward declaration of struct resource
- replace insert_resource() with request_resource() in fill_list()
- add __init specifier to arch_xen_unpopulated_init()
---
drivers/xen/unpopulated-alloc.c | 83 +++++++++++++++++++++++++++++++++++++----
include/xen/xen.h | 2 +
2 files changed, 78 insertions(+), 7 deletions(-)
diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c
index a03dc5b..07d3578 100644
--- a/drivers/xen/unpopulated-alloc.c
+++ b/drivers/xen/unpopulated-alloc.c
@@ -8,6 +8,7 @@
#include <asm/page.h>
+#include <xen/balloon.h>
#include <xen/page.h>
#include <xen/xen.h>
@@ -15,13 +16,29 @@ 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;
+ struct resource *res, *tmp_res = NULL;
void *vaddr;
unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
- int ret = -ENOMEM;
+ struct range mhp_range;
+ int ret;
res = kzalloc(sizeof(*res), GFP_KERNEL);
if (!res)
@@ -30,14 +47,40 @@ static int fill_list(unsigned int nr_pages)
res->name = "Xen scratch";
res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
- ret = allocate_resource(&iomem_resource, res,
- alloc_pages * PAGE_SIZE, 0, -1,
+ 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 (!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;
@@ -95,6 +138,11 @@ static int fill_list(unsigned int nr_pages)
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);
@@ -112,6 +160,14 @@ 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);
@@ -159,6 +215,11 @@ 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;
@@ -169,9 +230,11 @@ void xen_free_unpopulated_pages(unsigned int nr_pages,
struct page **pages)
}
EXPORT_SYMBOL(xen_free_unpopulated_pages);
-#ifdef CONFIG_XEN_PV
static int __init init(void)
{
+ int ret;
+
+#ifdef CONFIG_XEN_PV
unsigned int i;
if (!xen_domain())
@@ -196,8 +259,14 @@ static int __init init(void)
list_count++;
}
}
+#endif
- return 0;
+ ret = arch_xen_unpopulated_init(&target_resource);
+ if (ret) {
+ pr_err("xen:unpopulated: Cannot initialize target resource\n");
+ target_resource = NULL;
+ }
+
+ return ret;
}
subsys_initcall(init);
-#endif
diff --git a/include/xen/xen.h b/include/xen/xen.h
index 86c5b37..a99bab8 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -55,6 +55,8 @@ extern u64 xen_saved_max_mem_size;
#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages);
void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages);
+#include <linux/ioport.h>
+int arch_xen_unpopulated_init(struct resource **res);
#else
#include <xen/balloon.h>
static inline int xen_alloc_unpopulated_pages(unsigned int nr_pages,
--
2.7.4
