Re: [PATCH] x86emul: SYSRET must change CPL

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/04/2020 13:14, Jan Beulich wrote:
> The special AMD behavior of leaving SS mostly alone wasn't really
> complete: We need to adjust CPL aka SS.DPL.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Oops.

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

>
> --- a/xen/arch/x86/x86_emulate/x86_emulate.c
> +++ b/xen/arch/x86/x86_emulate/x86_emulate.c
> @@ -6022,6 +6022,8 @@ x86_emulate(
>  
>              /* There's explicitly no RPL adjustment here. */
>              sreg.sel = (msr_val >> 48) + 8;
> +            /* But DPL needs adjustment, for the new CPL to be correct. */
> +            sreg.dpl = 3;
>          }
>  
>  #ifdef __x86_64__