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Re: [PATCH v3] x86emul: further correct 64-bit mode zero count repeated string insn handling
On 1/22/25 2:29 PM, Jan Beulich wrote:
On 22.01.2025 11:23, Roger Pau Monné wrote:
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>
Thanks. I'm uncertain though whether with concerns Andrew had voiced (maybe
just on irc/Matrix) I may go ahead and commit this. Andrew?
In any event - Oleksii, I guess I'd need a release ack here (or an indication
to defer to 4.21).
If Andrew has no objections to this patch, then: R-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Otherwise, it would be better to defer the patch to 4.21 or wait until the objections are resolved or clarified as unnecessary.
~ Oleksii
---
Partly RFC for none of this being documented anywhere (and it partly
being model specific); inquiry pending.
Did you get any reply on this?
No, and to be honest I also didn't have much hope I would get any reply.
Jan
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