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: <bd18fe0e-6e74-f89c-a754-15da2aa2eb96@intel.com>
Date:   Sat, 2 Apr 2022 10:40:32 +0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Firefox/91.0 Thunderbird/91.6.1
Subject: Re: [RFC PATCH v5 008/104] KVM: TDX: Add a function to initialize TDX
 module
Content-Language: en-US
To:     Isaku Yamahata <isaku.yamahata@gmail.com>
Cc:     Kai Huang <kai.huang@intel.com>, isaku.yamahata@intel.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Paolo Bonzini <pbonzini@redhat.com>,
        Jim Mattson <jmattson@google.com>, erdemaktas@google.com,
        Connor Kuehl <ckuehl@redhat.com>,
        Sean Christopherson <seanjc@google.com>
References: <cover.1646422845.git.isaku.yamahata@intel.com>
 <b92217283fa96b85e9a683ca3fcf1b368cf8d1c4.1646422845.git.isaku.yamahata@intel.com>
 <36aac3cb7c7447db6454ee396e25eea3bad378e6.camel@intel.com>
 <20220331194144.GA2084469@ls.amr.corp.intel.com>
 <d63042a2-91d8-5555-1bac-4d908e03da2b@intel.com>
 <20220401201806.GA2862421@ls.amr.corp.intel.com>
From:   Xiaoyao Li <xiaoyao.li@intel.com>
In-Reply-To: <20220401201806.GA2862421@ls.amr.corp.intel.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 4/2/2022 4:18 AM, Isaku Yamahata wrote:
> On Fri, Apr 01, 2022 at 02:56:40PM +0800,
> Xiaoyao Li <xiaoyao.li@intel.com> wrote:
> 
>> On 4/1/2022 3:41 AM, Isaku Yamahata wrote:
>>> On Thu, Mar 31, 2022 at 04:31:10PM +1300,
>>> Kai Huang <kai.huang@intel.com> wrote:
>>>
>>>> On Fri, 2022-03-04 at 11:48 -0800, isaku.yamahata@intel.com wrote:
>>>>> From: Isaku Yamahata <isaku.yamahata@intel.com>
>>>
>>>>> Add a wrapper function to initialize the TDX module and get system-wide
>>>>> parameters via those APIs.  Because TDX requires VMX enabled, It will be
>>>>> called on-demand when the first guest TD is created via x86 KVM init_vm
>>>>> callback.
>>>>
>>>> Why not just merge this patch with the change where you implement the init_vm
>>>> callback?  Then you can just declare this patch as "detect and initialize TDX
>>>> module when first VM is created", or something like that..
>>>
>>> Ok. Anyway in the next respoin, tdx module initialization will be done when
>>> loading kvm_intel.ko.  So the whole part will be changed and will be a part
>>> of module loading.
>>
>> Will we change the GET_TDX_CAPABILITIES ioctl back to KVM scope?
> 
> No because it system scoped KVM_TDX_CAPABILITIES requires one more callback for
> it.  We can reduce the change.
> 
> Or do you have any use case for system scoped KVM_TDX_CAPABILITIES?

No. Just to confirm.

on the other hand, vm-scope IOCTL seems more flexible if different 
capabilities are reported per VM in the future.