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Date:   Mon, 21 Nov 2022 16:44:50 -0800
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Subject: Re: [PATCH v7 03/20] x86/virt/tdx: Disable TDX if X2APIC is not
 enabled
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To:     "Huang, Kai" <kai.huang@intel.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc:     "Luck, Tony" <tony.luck@intel.com>,
        "bagasdotme@gmail.com" <bagasdotme@gmail.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>,
        "Christopherson,, Sean" <seanjc@google.com>,
        "Chatre, Reinette" <reinette.chatre@intel.com>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "Yamahata, Isaku" <isaku.yamahata@intel.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "Shahar, Sagi" <sagis@google.com>,
        "imammedo@redhat.com" <imammedo@redhat.com>,
        "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>
References: <cover.1668988357.git.kai.huang@intel.com>
 <c5f484c1a87ee052597fd5f539cf021f158755b9.1668988357.git.kai.huang@intel.com>
 <87e17024-755d-e195-d9ea-ef62a4de6aa8@intel.com>
 <f9918596c4013444428899aca2cfa73b1f18c703.camel@intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <f9918596c4013444428899aca2cfa73b1f18c703.camel@intel.com>
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On 11/21/22 16:30, Huang, Kai wrote:
> 
> How about still having a patch to make INTEL_TDX_HOST depend on X86_X2APIC but
> with something below in the changelog?
> 
> "
> TDX capable platforms are locked to X2APIC mode and cannot fall back to the
> legacy xAPIC mode when TDX is enabled by the BIOS.   It doesn't make sense to
> turn on INTEL_TDX_HOST while X86_X2APIC is not enabled.  Make INTEL_TDX_HOST
> depend on X86_X2APIC.

That's fine and it makes logical sense as a dependency.  TDX host
support requires x2APIC.  Period.