linux-kernel - Re: [PATCH 04/12] x86/sev: Do not hardcode GHCB protocol version

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Message-ID: <YQT5WPANjqXSytPR@suse.de>
Date:   Sat, 31 Jul 2021 09:18:48 +0200
From:   Joerg Roedel <jroedel@...e.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     Joerg Roedel <joro@...tes.org>, x86@...nel.org,
        Eric Biederman <ebiederm@...ssion.com>,
        kexec@...ts.infradead.org, hpa@...or.com,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Martin Radev <martin.b.radev@...il.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 04/12] x86/sev: Do not hardcode GHCB protocol version

Hi Tom,

On Wed, Jul 21, 2021 at 04:17:38PM -0500, Tom Lendacky wrote:
> On 7/21/21 9:20 AM, Joerg Roedel wrote:
> >  	/* Fill in protocol and format specifiers */
> > -	ghcb->protocol_version = GHCB_PROTOCOL_MAX;
> > +	ghcb->protocol_version = sev_get_ghcb_proto_ver();
> 
> So this probably needs better clarification in the spec, but the GHCB
> version field is for the GHCB structure layout. So if you don't plan to
> use the XSS field that was added for version 2 of the layout, then you
> should report the GHCB structure version as 1.

Yeah, this makes sense, exept for the struct field-name ;) But anyway, I
keep the version field at 1 for now.

Regards,

	Joerg