1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index a8a66a50d446..2a4add9634ce 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -194,6 +194,14 @@ char * __init xen_memory_setup(void)
                         end -= delta;
 
                         extra_pages += PFN_DOWN(delta);
+                        /*
+                         * Set RAM below 4GB that is not for us to be unusable.
+                         * This prevents "System RAM" address space from being
+                         * used as potential resource for I/O address (happens
+                         * when 'allocate_resource' is called).
+                         */
+                        if (delta && end < 0x100000000UL)
+                                e820_add_region(end, delta, E820_UNUSABLE);
                 }
 
                 if (map[i].size > 0 && end > xen_extra_mem_start)