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-rw-r--r--drivers/xen/Kconfig17
-rw-r--r--drivers/xen/balloon.c23
2 files changed, 40 insertions, 0 deletions
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index b812462083fc..94d96809e686 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -55,6 +55,23 @@ config XEN_BALLOON_MEMORY_HOTPLUG
In that case step 3 should be omitted.
+config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
+ int "Hotplugged memory limit (in GiB) for a PV guest"
+ default 512 if X86_64
+ default 4 if X86_32
+ range 0 64 if X86_32
+ depends on XEN_HAVE_PVMMU
+ depends on XEN_BALLOON_MEMORY_HOTPLUG
+ help
+ Maxmium amount of memory (in GiB) that a PV guest can be
+ expanded to when using memory hotplug.
+
+ A PV guest can have more memory than this limit if is
+ started with a larger maximum.
+
+ This value is used to allocate enough space in internal
+ tables needed for physical memory administration.
+
config XEN_SCRUB_PAGES
bool "Scrub pages before returning them to system"
depends on XEN_BALLOON
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 0b52d92cb2e5..fd933695f232 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -229,6 +229,29 @@ static enum bp_state reserve_additional_memory(long credit)
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) {