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authorOleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>2021-12-09 23:05:33 +0300
committerJuergen Gross <jgross@suse.com>2022-01-06 11:53:35 +0300
commit9dd060afe2dfd4e3f67b6732fdc681e52cd7cbd9 (patch)
treecc90903ec0160f626524641ee26a1276a6d68fa6 /drivers/xen
parent5e1cdb8ee5e76bffbc11d300eebbb5193c7de530 (diff)
downloadlinux-9dd060afe2dfd4e3f67b6732fdc681e52cd7cbd9.tar.xz
xen/balloon: Bring alloc(free)_xenballooned_pages helpers back
This patch rolls back some of the changes introduced by commit 121f2faca2c0a "xen/balloon: rename alloc/free_xenballooned_pages" in order to make possible to still allocate xenballooned pages if CONFIG_XEN_UNPOPULATED_ALLOC is enabled. On Arm the unpopulated pages will be allocated on top of extended regions provided by Xen via device-tree (the subsequent patches will add required bits to support unpopulated-alloc feature on Arm). The problem is that extended regions feature has been introduced into Xen quite recently (during 4.16 release cycle). So this effectively means that Linux must only use unpopulated-alloc on Arm if it is running on "new Xen" which advertises these regions. But, it will only be known after parsing the "hypervisor" node at boot time, so before doing that we cannot assume anything. In order to keep working if CONFIG_XEN_UNPOPULATED_ALLOC is enabled and the extended regions are not advertised (Linux is running on "old Xen", etc) we need the fallback to alloc_xenballooned_pages(). This way we wouldn't reduce the amount of memory usable (wasting RAM pages) for any of the external mappings anymore (and eliminate XSA-300) with "new Xen", but would be still functional ballooning out RAM pages with "old Xen". Also rename alloc(free)_xenballooned_pages to xen_alloc(free)_ballooned_pages and make xen_alloc(free)_unpopulated_pages static inline in xen.h if CONFIG_XEN_UNPOPULATED_ALLOC is disabled. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1639080336-26573-4-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/balloon.c20
1 files changed, 9 insertions, 11 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ba2ea11e0d3d..a2c4fc49c483 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -581,7 +581,6 @@ void balloon_set_new_target(unsigned long target)
}
EXPORT_SYMBOL_GPL(balloon_set_new_target);
-#ifndef CONFIG_XEN_UNPOPULATED_ALLOC
static int add_ballooned_pages(unsigned int nr_pages)
{
enum bp_state st;
@@ -610,12 +609,12 @@ static int add_ballooned_pages(unsigned int nr_pages)
}
/**
- * xen_alloc_unpopulated_pages - get pages that have been ballooned out
+ * xen_alloc_ballooned_pages - get pages that have been ballooned out
* @nr_pages: Number of pages to get
* @pages: pages returned
* @return 0 on success, error otherwise
*/
-int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages)
{
unsigned int pgno = 0;
struct page *page;
@@ -652,23 +651,23 @@ int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **pages)
return 0;
out_undo:
mutex_unlock(&balloon_mutex);
- xen_free_unpopulated_pages(pgno, pages);
+ xen_free_ballooned_pages(pgno, pages);
/*
- * NB: free_xenballooned_pages will only subtract pgno pages, but since
+ * NB: xen_free_ballooned_pages will only subtract pgno pages, but since
* target_unpopulated is incremented with nr_pages at the start we need
* to remove the remaining ones also, or accounting will be screwed.
*/
balloon_stats.target_unpopulated -= nr_pages - pgno;
return ret;
}
-EXPORT_SYMBOL(xen_alloc_unpopulated_pages);
+EXPORT_SYMBOL(xen_alloc_ballooned_pages);
/**
- * xen_free_unpopulated_pages - return pages retrieved with get_ballooned_pages
+ * xen_free_ballooned_pages - return pages retrieved with get_ballooned_pages
* @nr_pages: Number of pages
* @pages: pages to return
*/
-void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
+void xen_free_ballooned_pages(unsigned int nr_pages, struct page **pages)
{
unsigned int i;
@@ -687,9 +686,9 @@ void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **pages)
mutex_unlock(&balloon_mutex);
}
-EXPORT_SYMBOL(xen_free_unpopulated_pages);
+EXPORT_SYMBOL(xen_free_ballooned_pages);
-#if defined(CONFIG_XEN_PV)
+#if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
static void __init balloon_add_region(unsigned long start_pfn,
unsigned long pages)
{
@@ -712,7 +711,6 @@ static void __init balloon_add_region(unsigned long start_pfn,
balloon_stats.total_pages += extra_pfn_end - start_pfn;
}
#endif
-#endif
static int __init balloon_init(void)
{