Re: [PATCH v5 3/6] x86/sev-es: Split up runtime #VC handler for correct state tracking

Joerg Roedel
2021-06-16T19:01:36Z

Hi Peter,

sorry, missed this email before sending out v6.

On Wed, Jun 16, 2021 at 06:04:26PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 14, 2021 at 03:53:24PM +0200, Joerg Roedel wrote:
> > _ASM_NOKPROBE(\asmsym)
> > SYM_CODE_END(\asmsym)
>
> Consistency with idtentry_mce_db would seem to suggest using \cfunc and
> noist_\cfunc.
>
> amluto, tglx: do we have strong feelings on consistency?

Yeah, but this distinction does not make sense here, as none of the #VC
handlers C functions run on the actual #VC IST stack. The from-kernel
function might run on the fall-back stack (not really possible today
unless the hypervisor does something nasty). And the difference between
the fall-back stack and the actual IST stack is, that on the fall-back
stack nesting #VC exceptions is still supported.

> > + vc_handle_trap_db(regs);
>
> It's a bit sad this does user_mode(regs) again.

Okay, I will change this according your comments.

Thanks,

Joerg