xen/balloon: before adding hotplugged memory, set frames to invalid
Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
regions above the end of RAM as 1:1") introduced a regression.
To be able to add memory pages which were added via memory hotplug to
a pv domain, the pages must be "invalid" instead of "identity" in the
p2m list before they can be added.
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: <stable@vger.kernel.org> # 3.16+
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 0b52d92..fd93369 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -229,6 +229,29 @@
balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
+#ifdef CONFIG_XEN_HAVE_PVMMU
+ /*
+ * add_memory() will build page tables for the new memory so
+ * the p2m must contain invalid entries so the correct
+ * non-present PTEs will be written.
+ *
+ * If a failure occurs, the original (identity) p2m entries
+ * are not restored since this region is now known not to
+ * conflict with any devices.
+ */
+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ unsigned long pfn, i;
+
+ pfn = PFN_DOWN(hotplug_start_paddr);
+ for (i = 0; i < balloon_hotplug; i++) {
+ if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
+ pr_warn("set_phys_to_machine() failed, no memory added\n");
+ return BP_ECANCELED;
+ }
+ }
+ }
+#endif
+
rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT);
if (rc) {