diff -r 8a9f81672c76 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c	Wed Aug 12 14:27:52 2009 +0100
+++ b/xen/arch/x86/hvm/hvm.c	Thu Aug 13 13:47:04 2009 +0200
@@ -1850,6 +1850,14 @@ int hvm_msr_read_intercept(struct cpu_us
          msr_content = 0;
          break;
 
+    case MSR_AMD64_NB_CFG:
+         /* This AMD-only register may be accessed if this HVM guest
+          * has been migrated to an Intel host. This fixes a guest crash
+          * in this case.
+          */
+         msr_content = 0;
+         break;
+
     default:
         ret = mce_rdmsr(ecx, &lo, &hi);
         if ( ret < 0 )
@@ -1949,6 +1957,10 @@ int hvm_msr_write_intercept(struct cpu_u
             goto gp_fault;
         break;
 
+    case MSR_AMD64_NB_CFG:
+        /* ignore the write */
+        break;
+
     default:
         ret = mce_wrmsr(ecx, msr_content);
         if ( ret < 0 )