1 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index df118a825f39..46d6d21dbdbe 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -184,6 +184,19 @@ static unsigned long __init xen_set_identity(const struct e820entry *list,
                                         PFN_UP(start_pci), PFN_DOWN(last));
         return identity;
 }
+
+static unsigned long __init xen_get_max_pages(void)
+{
+        unsigned long max_pages = MAX_DOMAIN_PAGES;
+        domid_t domid = DOMID_SELF;
+        int ret;
+
+        ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
+        if (ret > 0)
+                max_pages = ret;
+        return min(max_pages, MAX_DOMAIN_PAGES);
+}
+
 /**
  * machine_specific_memory_setup - Hook for machine specific memory setup.
  **/
@@ -292,6 +305,14 @@ char * __init xen_memory_setup(void)
 
         sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
 
+        extra_limit = xen_get_max_pages();
+        if (max_pfn + extra_pages > extra_limit) {
+                if (extra_limit > max_pfn)
+                        extra_pages = extra_limit - max_pfn;
+                else
+                        extra_pages = 0;
+        }
+
         extra_pages += xen_return_unused_memory(xen_start_info->nr_pages, &e820);
 
         /*