From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Andrew Cooper <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>
Subject: Re: [PATCH v3] x86emul: further correct 64-bit mode zero count repeated string insn handling
Date: Wed, 22 Jan 2025 11:23:54 +0100 [thread overview]
Message-ID: <Z5DHOknjrhMoAGz6@macbook.local> (raw)
In-Reply-To: <2e81cf29-65fd-74fc-db4f-95c453acc327@suse.com>
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@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
> ---
> 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.
next prev parent reply other threads:[~2025-01-22 10:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-04 5:58 [PATCH v3] x86emul: further correct 64-bit mode zero count repeated string insn handling Jan Beulich
2025-01-22 10:23 ` Roger Pau Monné [this message]
2025-01-22 13:29 ` Jan Beulich
2025-01-22 16:01 ` Oleksii Kurochko
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