Merge tag 'stable/for-linus-3.14-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull Xen bugfixes from David Vrabel:
 "Fix two bugs that cause x86 PV guest crashes.

  1. Ballooning a 32-bit guest would eventually crash it.

  2. Revert a broken fix for a regression with NUMA_BALACING.  The bad
     fix caused PV guests to crash after migration.  This is not ideal
     but unpicking the madness that is _PAGE_NUMA == _PAGE_PROTNONE will
     take a while longer"

* tag 'stable/for-linus-3.14-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  Revert "xen: properly account for _PAGE_NUMA during xen pte translations"
  xen/balloon: flush persistent kmaps in correct position

1 files changed, 18 insertions, 6 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 37d06ea624aa..61a6ac8fa8fc 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -399,11 +399,25 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 			state = BP_EAGAIN;
 			break;
 		}
+		scrub_page(page);
 
-		pfn = page_to_pfn(page);
-		frame_list[i] = pfn_to_mfn(pfn);
+		frame_list[i] = page_to_pfn(page);
+	}
 
-		scrub_page(page);
+	/*
+	 * Ensure that ballooned highmem pages don't have kmaps.
+	 *
+	 * Do this before changing the p2m as kmap_flush_unused()
+	 * reads PTEs to obtain pages (and hence needs the original
+	 * p2m entry).
+	 */
+	kmap_flush_unused();
+
+	/* Update direct mapping, invalidate P2M, and add to balloon. */
+	for (i = 0; i < nr_pages; i++) {
+		pfn = frame_list[i];
+		frame_list[i] = pfn_to_mfn(pfn);
+		page = pfn_to_page(pfn);
 
 #ifdef CONFIG_XEN_HAVE_PVMMU
 		/*
@@ -429,11 +443,9 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 		}
 #endif
 
-		balloon_append(pfn_to_page(pfn));
+		balloon_append(page);
 	}
 
-	/* Ensure that ballooned highmem pages don't have kmaps. */
-	kmap_flush_unused();
 	flush_tlb_all();
 
 	set_xen_guest_handle(reservation.extent_start, frame_list);