linux-kernel - Re: [PATCH Part1 RFC v4 02/36] x86/sev: Save the negotiated GHCB version

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Date:   Tue, 10 Aug 2021 08:17:00 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        linux-crypto@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>, tony.luck@...el.com,
        npmccallum@...hat.com, brijesh.ksingh@...il.com
Subject: Re: [PATCH Part1 RFC v4 02/36] x86/sev: Save the negotiated GHCB
 version



On 8/10/21 5:01 AM, Borislav Petkov wrote:
> On Wed, Jul 07, 2021 at 01:14:32PM -0500, Brijesh Singh wrote:
>> The SEV-ES guest calls the sev_es_negotiate_protocol() to negotiate the
>> GHCB protocol version before establishing the GHCB. Cache the negotiated
>> GHCB version so that it can be used later.
>>
>> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
>> ---
>>   arch/x86/include/asm/sev.h   |  2 +-
>>   arch/x86/kernel/sev-shared.c | 17 ++++++++++++++---
>>   2 files changed, 15 insertions(+), 4 deletions(-)
> 
> Also, while looking at this, all those defines in sev-common.h were
> bothering me for a while now because they're an unreadable mess because
> I have to go look at the GHCB spec, decode the corresponding MSR
> protocol request and then go and piece together each request value by
> verifying the masks...
> 
> So I did the below which is, IMO, a lot more readable as you can follow
> it directly with the spec opened in parallel.
> 
> Thus, if you don't have a better idea, I'd ask you to please add this to
> your set and continue defining the new MSR protocol requests this way so
> that it can be readable.
> 

thanks Boris, I will include this in my series and rework the remaining 
patches to align with it.

-brijesh