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;
Date:   Wed, 5 Jul 2023 14:21:09 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Huang, Kai" <kai.huang@intel.com>
Cc:     "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Luck, Tony" <tony.luck@intel.com>,
        "david@redhat.com" <david@redhat.com>,
        "bagasdotme@gmail.com" <bagasdotme@gmail.com>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
        "kirill.shutemov@linux.intel.com" <kirill.shutemov@linux.intel.com>,
        "Chatre, Reinette" <reinette.chatre@intel.com>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "Yamahata, Isaku" <isaku.yamahata@intel.com>,
        "nik.borisov@suse.com" <nik.borisov@suse.com>,
        "hpa@zytor.com" <hpa@zytor.com>, "Shahar, Sagi" <sagis@google.com>,
        "imammedo@redhat.com" <imammedo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>, "Gao, Chao" <chao.gao@intel.com>,
        "Brown, Len" <len.brown@intel.com>,
        "sathyanarayanan.kuppuswamy@linux.intel.com" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        "Huang, Ying" <ying.huang@intel.com>,
        "Williams, Dan J" <dan.j.williams@intel.com>,
        "x86@kernel.org" <x86@kernel.org>
Subject: Re: [PATCH v12 20/22] x86/virt/tdx: Allow SEAMCALL to handle #UD and
 #GP
Message-ID: <20230705122109.GA4253@hirez.programming.kicks-ass.net>
References: <c124550719716f1f7759c2bdea70f4722d8e0167.1687784645.git.kai.huang@intel.com>
 <20230628152900.GI2438817@hirez.programming.kicks-ass.net>
 <20230628203823.GR38236@hirez.programming.kicks-ass.net>
 <42e13ccf7f27a68c0dd64640eed378c38ef40967.camel@intel.com>
 <20230630100659.GF2533791@hirez.programming.kicks-ass.net>
 <20230630102141.GA2534364@hirez.programming.kicks-ass.net>
 <20230630120650.GB2534364@hirez.programming.kicks-ass.net>
 <fdd81fbd2424d8da04f98d156668cad5e73c740b.camel@intel.com>
 <20230705102137.GX4253@hirez.programming.kicks-ass.net>
 <ab3dea02892920cd6640a31a9c846afd6c6a9d54.camel@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <ab3dea02892920cd6640a31a9c846afd6c6a9d54.camel@intel.com>
Precedence: bulk

On Wed, Jul 05, 2023 at 11:34:53AM +0000, Huang, Kai wrote:

> Yeah I think from long-term's view, since SEAMCALLs to support live migration
> pretty much uses all RCX/RDX/R8-R15 as input/output, it seems reasonable to
> unify all of them, although I guess there might be some special handling to
> VP.VMCALL and/or VP.ENTER, e.g., below:
> 
>         /* TDVMCALL leaf return code is in R10 */                              
>         movq %r10, %rax

Well, that's a problem fo whoever does tdcall(0, &args), no?

But did I say it had a crap calling convention already?