Re: [PATCH v5 49/65] i386/tdx: handle TDG.VP.VMCALL<GetQuote>

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 2/29/2024 9:28 PM, Markus Armbruster wrote:
> Xiaoyao Li <xiaoyao.li@intel.com> writes:
> 
>> On 2/29/2024 4:40 PM, Markus Armbruster wrote:
>>> Xiaoyao Li <xiaoyao.li@intel.com> writes:
>>>
>>>> From: Isaku Yamahata <isaku.yamahata@intel.com>
>>>>
>>>> Add property "quote-generation-socket" to tdx-guest, which is a property
>>>> of type SocketAddress to specify Quote Generation Service(QGS).
>>>>
>>>> On request of GetQuote, it connects to the QGS socket, read request
>>>> data from shared guest memory, send the request data to the QGS,
>>>> and store the response into shared guest memory, at last notify
>>>> TD guest by interrupt.
>>>>
>>>> command line example:
>>>>     qemu-system-x86_64 \
>>>>       -object '{"qom-type":"tdx-guest","id":"tdx0","quote-generation-socket":{"type": "vsock", "cid":"1","port":"1234"}}' \
>>>>       -machine confidential-guest-support=tdx0
>>>>
>>>> Note, above example uses vsock type socket because the QGS we used
>>>> implements the vsock socket. It can be other types, like UNIX socket,
>>>> which depends on the implementation of QGS.
>>>>
>>>> To avoid no response from QGS server, setup a timer for the transaction.
>>>> If timeout, make it an error and interrupt guest. Define the threshold of
>>>> time to 30s at present, maybe change to other value if not appropriate.
>>>>
>>>> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
>>>> Codeveloped-by: Chenyi Qiang <chenyi.qiang@intel.com>
>>>> Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
>>>> Codeveloped-by: Xiaoyao Li <xiaoyao.li@intel.com>
>>>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>>>
>>> [...]
>>>
>>>> diff --git a/qapi/qom.json b/qapi/qom.json
>>>> index cac875349a3a..7b26b0a0d3aa 100644
>>>> --- a/qapi/qom.json
>>>> +++ b/qapi/qom.json
>>>> @@ -917,13 +917,19 @@
>>>>   #     (base64 encoded SHA384 digest). (A default value 0 of SHA384 is
>>>>   #     used when absent).
>>>>   #
>>>> +# @quote-generation-socket: socket address for Quote Generation
>>>> +#     Service (QGS).  QGS is a daemon running on the host.  User in
>>>> +#     TD guest cannot get TD quoting for attestation if QGS is not
>>>> +#     provided.  So admin should always provide it.
>>>
>>> This makes me wonder why it's optional.  Can you describe a use case for
>>> *not* specifying @quote-generation-socket?
>>
>> Maybe at last when all the TDX support lands on all the components, attestation will become a must for a TD guest to be usable.
>>
>> However, at least for today, booting and running a TD guest don't require attestation. So not provide it, doesn't affect anything excepting cannot get a Quote.
> 
> Maybe
> 
>    # @quote-generation-socket: Socket address for Quote Generation
>    #     Service (QGS).  QGS is a daemon running on the host.  Without
>    #     it, the guest will not be able to get a TD quote for
>    #     attestation.

Thanks! will update to it.

> [...]
>