xen/balloon: pre-allocate p2m entries for ballooned pages
Pages returned by alloc_xenballooned_pages() will be used for grant
mapping which will call set_phys_to_machine() (in PV guests).
Ballooned pages are set as INVALID_P2M_ENTRY in the p2m and thus may
be using the (shared) missing tables and a subsequent
set_phys_to_machine() will need to allocate new tables.
Since the grant mapping may be done from a context that cannot sleep,
the p2m entries must already be allocated.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 25fd1bd..f566623 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -602,6 +602,11 @@
page = balloon_retrieve(true);
if (page) {
pages[pgno++] = page;
+#ifdef CONFIG_XEN_HAVE_PVMMU
+ ret = xen_alloc_p2m_entry(page_to_pfn(page));
+ if (ret < 0)
+ goto out_undo;
+#endif
} else {
ret = add_ballooned_pages(nr_pages - pgno);
if (ret < 0)
