linux-kernel - Re: [RFC PATCH 00/62] Linux as SEV-ES Guest Support

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Message-ID: <20200211154321.GB22063@8bytes.org>
Date:   Tue, 11 Feb 2020 16:43:21 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [RFC PATCH 00/62] Linux as SEV-ES Guest Support

On Tue, Feb 11, 2020 at 03:50:08PM +0100, Peter Zijlstra wrote:
 
> Oh gawd; so instead of improving the whole NMI situation, AMD went and
> made it worse still ?!?

Well, depends on how you want to see it. Under SEV-ES an IRET will not
re-open the NMI window, but the guest has to tell the hypervisor
explicitly when it is ready to receive new NMIs via the NMI_COMPLETE
message.  NMIs stay blocked even when an exception happens in the
handler, so this could also be seen as a (slight) improvement.

Regards,

	Joerg