linux-kernel - Re: [PATCH 50/62] x86/sev-es: Handle VMMCALL Events

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Message-ID: <20200212132220.GI20066@8bytes.org>
Date:   Wed, 12 Feb 2020 14:22:20 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        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: [PATCH 50/62] x86/sev-es: Handle VMMCALL Events

On Tue, Feb 11, 2020 at 04:14:53PM -0800, Andy Lutomirski wrote:
> 
> How about we just don’t do VMMCALL if we’re a SEV-ES guest?  Otherwise
> we add thousands of cycles of extra latency for no good reason.

True, but I left that as a future optimization for now, given the size
the patch-set already has. The idea is to add an abstraction around
VMMCALL for the support code of the various hypervisors and just do a
VMGEXIT in that wrapper when in an SEV-ES guest. But again, that is a
separate patch-set.

Regards,

	Joerg