Re: [PATCH v3] x86emul: further correct 64-bit mode zero count repeated string insn handling

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Aug 04, 2023 at 07:58:21AM +0200, Jan Beulich wrote:
> In an entirely different context I came across Linux commit 428e3d08574b
> ("KVM: x86: Fix zero iterations REP-string"), which points out that
> we're still doing things wrong: For one, there's no zero-extension at
> all on AMD. And then while RCX is zero-extended from 32 bits uniformly
> for all string instructions on newer hardware, RSI/RDI are only for MOVS
> and STOS on the systems I have access to. (On an old family 0xf system
> I've further found that for REP LODS even RCX is not zero-extended.)
> 
> Fixes: 79e996a89f69 ("x86emul: correct 64-bit mode repeated string insn 
> handling with zero count")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

> ---
> Partly RFC for none of this being documented anywhere (and it partly
> being model specific); inquiry pending.

Did you get any reply on this?

Thanks, Roger.