Re: [Xen-devel] Fwd: Xen-4.1.6.1 backport for XSA156

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.11.15 at 08:37, <JBeulich@xxxxxxxx> wrote:
> Actually there's no problem with ICEBP - just like INTnn it isn't itself
> interceptable (and the injection of vector 0x01 from the x86
> emulator path can't fully distinguish between ICEBP and INT $1  in
> these old versions anyway). So what you have should be good
> enough, albeit I think I'll code it slightly differently (keeping the fall-
> through in place).

Like this:

@@ -1364,7 +1358,6 @@ void vmx_inject_hw_exception(int trap, i
     switch ( trap )
     {
     case TRAP_debug:
-        type = X86_EVENTTYPE_SW_EXCEPTION;
         if ( guest_cpu_user_regs()->eflags & X86_EFLAGS_TF )
         {
             __restore_debug_registers(curr);
@@ -1379,9 +1372,11 @@ void vmx_inject_hw_exception(int trap, i
             domain_pause_for_debugger();
             return;
         }
-
-        type = X86_EVENTTYPE_SW_EXCEPTION;
-        __vmwrite(VM_ENTRY_INSTRUCTION_LEN, 1); /* int3 */
+        if ( trap == TRAP_int3 )
+        {
+            type = X86_EVENTTYPE_SW_EXCEPTION;
+            __vmwrite(VM_ENTRY_INSTRUCTION_LEN, 1);
+        }
     }
 
     if ( unlikely(intr_info & INTR_INFO_VALID_MASK) &&

Jan


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