--- xen-4.2.3-testing.orig/xen/include/asm-x86/hvm/hvm.h	2014-02-14 19:05:59.000000000 +0100
+++ xen-4.2.3-testing/xen/include/asm-x86/hvm/hvm.h	2014-02-17 07:43:05.000000000 +0100
@@ -374,7 +374,8 @@ static inline int hvm_do_pmu_interrupt(s
         (cpu_has_xsave ? X86_CR4_OSXSAVE : 0))))
 
 /* These exceptions must always be intercepted. */
-#define HVM_TRAP_MASK ((1U << TRAP_machine_check) | (1U << TRAP_invalid_op))
+#define HVM_TRAP_MASK ((1U << TRAP_machine_check) | (1U << TRAP_invalid_op) |\
+	(1 << TRAP_debug))
 
 /*
  * x86 event types. This enumeration is valid for:
--- xen-4.2.3-testing.orig/xen/arch/x86/hvm/vmx/vmcs.c	2014-02-17 07:48:43.000000000 +0100
+++ xen-4.2.3-testing/xen/arch/x86/hvm/vmx/vmcs.c	2014-02-17 10:16:25.000000000 +0100
@@ -168,7 +168,7 @@ static int vmx_init_vmcs_config(void)
            CPU_BASED_RDTSC_EXITING);
     opt = (CPU_BASED_ACTIVATE_MSR_BITMAP |
            CPU_BASED_TPR_SHADOW |
-           CPU_BASED_MONITOR_TRAP_FLAG |
+           /* CPU_BASED_MONITOR_TRAP_FLAG | */
            CPU_BASED_ACTIVATE_SECONDARY_CONTROLS);
     _vmx_cpu_based_exec_control = adjust_vmx_controls(
         "CPU-Based Exec Control", min, opt,
--- xen-4.2.3-testing.orig/xen/arch/x86/hvm/vmx/vmx.c	2014-02-18 08:04:23.000000000 +0100
+++ xen-4.2.3-testing/xen/arch/x86/hvm/vmx/vmx.c	2014-02-18 10:45:42.000000000 +0100
@@ -2646,7 +2646,11 @@ void vmx_vmexit_handler(struct cpu_user_
             HVMTRACE_1D(TRAP_DEBUG, exit_qualification);
             write_debugreg(6, exit_qualification | 0xffff0ff0);
             if ( !v->domain->debugger_attached || cpu_has_monitor_trap_flag )
-                goto exit_and_crash;
+            {
+                __restore_debug_registers(v);
+                hvm_inject_hw_exception(TRAP_debug, HVM_DELIVER_NO_ERROR_CODE);
+                break;
+            }
             domain_pause_for_debugger();
             break;
         case TRAP_int3: