Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <30220ec4-d35f-4a8a-4c08-959765ea6f26@intel.com>
Date:   Fri, 22 Jul 2022 14:24:33 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.9.1
Subject: Re: [PATCH v8 5/5] x86/tdx: Add Quote generation support
Content-Language: en-US
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kai Huang <kai.huang@intel.com>,
        Wander Lairson Costa <wander@redhat.com>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        linux-kernel@vger.kernel.org,
        "Nakajima, Jun" <jun.nakajima@intel.com>
References: <20220609025220.2615197-1-sathyanarayanan.kuppuswamy@linux.intel.com>
 <20220609025220.2615197-6-sathyanarayanan.kuppuswamy@linux.intel.com>
 <403cfccb-7fff-ab0b-8ebd-e5b04e631571@intel.com>
 <20220722190524.GA3299911@ls.amr.corp.intel.com>
 <18578c5a-7a35-ab20-467c-80141b0410a8@intel.com>
 <b8ea1778-02c1-b688-896d-dbb231eddf23@linux.intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <b8ea1778-02c1-b688-896d-dbb231eddf23@linux.intel.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 7/22/22 14:18, Sathyanarayanan Kuppuswamy wrote:
> For cases where your platform does not want to support or enable the generic
> interface (like vsock), isn't it better to have a fallback approach? I am not
> saying we should have such an ABI for all cases. But attestation is a must-have
> feature for the TDX guest, and we want to support it in all TD guest platforms.
> I think the GHCI ABI is added to meet this requirement.

This logic is basically: it's in the spec so it must be useful.  I don't
buy that, sorry.