Commit 4a69c909 authored Jul 22, 2015 by David Vrabel

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>

parent 8edfcf88

drivers/xen/balloon.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -602,6 +602,11 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages)
		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)