Re: [RFC PATCH v3 17/36] pflash_cfi01/tdx: Introduce ram_mode of pflash for TDVF

[Xiaoyao Li]

On 3/24/2022 3:58 PM, Gerd Hoffmann wrote:
>    Hi,
>
> > > > Well, if persistent vars are not supported anyway there is little reason
> > > > to split the firmware into CODE and VARS files.  You can use just use
> > > > OVMF.fd with a single pflash device.  libvirt recently got support for
> > > > that.
> > >
> > > Agreed.
> >
> > The purpose of using split firmware is that people can share the same
> > code.fd while using different vars.fd
>
> Using different vars.fd files is pointless though when changes are never
> written back ...

Yes, I agree on this.

Off the topic. If we really want to NVRAM capability to TDX guest, 1) we 
can use the PV interface issue MMIO write in OVMF, like what SEV does in 
OVMF. 2) map OVMF as shared, thus existing pflash works well.

However, both options will expose the content to VMM, which loses 
confidentiality.

> take care,
>    Gerd