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

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Date:   Fri, 17 Dec 2021 11:05:57 +0100
From:   Joerg Roedel <jroedel@...e.de>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org, 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>,
        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 Tue, Dec 14, 2021 at 10:51:27PM +0100, Borislav Petkov wrote:
> 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.

While it is true that the exit path can't trigger #VC right now, it will
be able with SNP.

So this change makes sense, either now or as part of the SNP-guest
patch-set.

Regards,

	Joerg