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authorDavid Hildenbrand <david@redhat.com>2019-03-14 17:02:56 +0100
committerJuergen Gross <jgross@suse.com>2019-03-15 15:35:35 +0100
commit0266def913771e718fd0c998eecb072e0685e2c9 (patch)
tree1d503c09f9630e1d17424c44b502c0d0ea4b2a8d
parentf261c4e529dac5608a604d3dd3ae1cd2adf23c89 (diff)
downloadlinux-0-day-0266def913771e718fd0c998eecb072e0685e2c9.tar.gz
linux-0-day-0266def913771e718fd0c998eecb072e0685e2c9.tar.xz
xen/balloon: Fix mapping PG_offline pages to user space
The XEN balloon driver - in contrast to other balloon drivers - allows to map some inflated pages to user space. Such pages are allocated via alloc_xenballooned_pages() and freed via free_xenballooned_pages(). The pfn space of these allocated pages is used to map other things by the hypervisor using hypercalls. Pages marked with PG_offline must never be mapped to user space (as this page type uses the mapcount field of struct pages). So what we can do is, clear/set PG_offline when allocating/freeing an inflated pages. This way, most inflated pages can be excluded by dumping tools and the "reused for other purpose" balloon pages are correctly not marked as PG_offline. Fixes: 77c4adf6a6df (xen/balloon: mark inflated pages PG_offline) Reported-by: Julien Grall <julien.grall@arm.com> Tested-by: Julien Grall <julien.grall@arm.com> Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com>
-rw-r--r--drivers/xen/balloon.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 39b229f9e256..d37dd5bb7a8f 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -604,6 +604,7 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages)
while (pgno < nr_pages) {
page = balloon_retrieve(true);
if (page) {
+ __ClearPageOffline(page);
pages[pgno++] = page;
#ifdef CONFIG_XEN_HAVE_PVMMU
/*
@@ -645,8 +646,10 @@ void free_xenballooned_pages(int nr_pages, struct page **pages)
mutex_lock(&balloon_mutex);
for (i = 0; i < nr_pages; i++) {
- if (pages[i])
+ if (pages[i]) {
+ __SetPageOffline(pages[i]);
balloon_append(pages[i]);
+ }
}
balloon_stats.target_unpopulated -= nr_pages;