Re: [Xen-devel] [PATCH 5/7] x86emul: vendor specific SYSENTER/SYSEXIT behavior in long mode

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/03/2020 16:28, Jan Beulich wrote:
> Intel CPUs permit both insns there while AMD ones don't.
>
> While at it also
> - drop the ring 0 check from SYSENTER handling - neither Intel's nor
>   AMD's insn pages have any indication of #GP(0) getting raised when
>   executed from ring 0, and trying it out in practice also confirms
>   the check shouldn't be there,
> - move SYSENTER segment register writing until after the (in principle
>   able to fail) MSR reads.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

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