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

[Stefan Bader <stefan.bader@xxxxxxxxxxxxx>]

On 23.11.2015 08:51, Jan Beulich wrote:
>>>> 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) &&
> 

Yeah, for my side I think I stick with what I had because I already have now run
that variant through testing. But I will include both variants when talking to
the Debian guys.

-Stefan
> Jan
>

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