linux-kernel - Re: [PATCH 3/3] x86/sev: The code for returning to user space is also in syscall gap

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Message-ID: <CAJhGHyAFQLgGM-Lxn_DWeQWYuy+42hC7wtxSG3tFHE0brJJqPw@mail.gmail.com>
Date:   Tue, 12 Apr 2022 21:00:12 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Oleg Nesterov <oleg@...hat.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [PATCH 3/3] x86/sev: The code for returning to user space is also
 in syscall gap

On Wed, Dec 15, 2021 at 5:51 AM Borislav Petkov <bp@...en8.de> wrote:
>
> + Tom and leaving the whole mail un-trimmed for him.
>
> On Mon, Dec 13, 2021 at 12:22:15PM +0800, Lai Jiangshan wrote:
> > From: Lai Jiangshan <laijs@...ux.alibaba.com>
> >
> > When returning to user space, the %rsp is user controlled value.
>
> And?
>
> I'd expect to see here some text analyzing the couple of instructions
> between those new labels you've added and whether a #VC can happen
> there.


Hello, Borislav

I resent the patch with an updated changelog mainly copied from
Joerg's reply.

https://lore.kernel.org/lkml/20220412124909.10467-1-jiangshanlai@gmail.com/


The other two patches in this patchset are omitted since they
make less sense which only harms only when the system owner
is deliberately doing stupid things.

thanks
Lai