Re: [PATCH 1/2] KVM: TDX: Handle TDG.VP.VMCALL<GetQuote>

[Binbin Wu <binbin.wu@linux.intel.com>]

On 4/3/2025 6:00 AM, Huang, Kai wrote:
>>>> +via the same buffer. The 'ret' field represents the return value.
>>>>
>>> return value of the GetQuote TDVMCALL?
>> Yes, thereturn code of the GetQuote TDVMCALL.
>>>> The userspace
>>>> +should update the return value before resuming the vCPU according to TDX GHCI
>>>> +spec.
>>>>
>>> I don't quite follow.  Why userspace should "update" the return value?
>> Because only userspace knows whether the request has been queued successfully.
>>
>> According to GHCI, TDG.VP.VMCALL<GetQuote> API allows one TD to issue multiple
>> requests. This is implementation specific as to how many concurrent requests
>> are allowed.  The TD should be able to handle TDG.VP.VMCALL_RETRY if it chooses
>> to issue multiple requests simultaneously.
>> So the userspace may set the return code as TDG.VP.VMCALL_RETRY.
> OK.  How about just say:
>
> The 'ret' field represents the return value of the GetQuote request.  KVM only
> bridges the request to userspace VMM after sanity checks, and the userspace VMM
> is responsible for setting up the return value since only userspace knows
> whether the request has been queued successfully or not.
>
This looks good to me.
Regarding the sanity checks, I would appreciate inputs from others.