Re: [PATCH V2 01/10] OvmfPkg: Add Tdx measurement data structure in WorkArea

["Gerd Hoffmann" <kraxel@redhat.com>]

On Thu, Jan 19, 2023 at 11:28:13AM +0800, Min Xu wrote:
> From: Min M Xu <min.m.xu@intel.com>
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4243
> 
> From the perspective of security any external input should be measured
> and extended to some registers (TPM PCRs or TDX RTMR registers).
> 
> There are below 2 external input in a Td guest:
>  - TdHob
>  - Configuration FV (CFV)
> 
> TdHob contains the resource information passed from VMM, such as
> unaccepted memory region. CFV contains the configurations, such as
> secure boot variables.
> 
> TdHob and CFV should be measured and extended to RTMRs before they're
> consumed. TdHob is consumed in the very early stage of boot process.
> At that moment the memory service is not ready. Cfv is consumed in
> PlatformPei to initialize the EmuVariableNvStore. To make the
> implementation simple and clean, these 2 external input are measured
> and extended to RTMRs in SEC phase. That is to say the tdx measurement
> is only supported in SEC phase.
> 
> After the measurement the hash values are stored in WorkArea. Then after
> the Hob service is available, these 2 measurement values are retrieved
> and GuidHobs for these 2 tdx measurements are generated.
> 
> This patch defines the structure of TDX_MEASUREMENTS_DATA in
> SEC_TDX_WORK_AREA to store above 2 tdx measurements. It can be extended
> to store more tdx measurements if needed in the future.

Acked-by: Gerd Hoffmann <kraxel@redhat.com>