Re: [PATCH 3/3] OvmfPkg: Initialize NvVarStore with Configuration FV in Td guest

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

On Wed, Jun 22, 2022 at 02:02:00AM +0000, Xu, Min M wrote:
> On June 20, 2022 7:01 PM, Gerd Hoffman wrote:
> > 
> > There is PcdEmuVariableNvStoreReserved for that.  How about just copying
> > the store to ram, then set PcdEmuVariableNvStoreReserved to the location
> > and let the existing logic handle it?

> There is ReserveEmuVariableNvStore in PlatformPei/Platform.c. This
> function is called to allocate storage for NV Variables.
> PcdEmuVariableNvStoreReserved is set in that function too. So we can
> copy the content to that reserved storage if it is tdx guest. Then we
> let the exiting logic to handle it. So I would like to extract
> ReserveEmuVariableNvStore to PlatformReserveEmuVariableNvStore (in
> PlatformInitLib) and call it in both PlatformPei/Platform.c and
> PeilesssStartup.c.

Moving the ReserveEmuVariableNvStore() function to PlatformInitLib make
sense.  Will be a bit more than pure code motion though, we probably
need a new variable in the platforminfo struct because PeilesssStartup.c
can't set PCDs.

Copying over the content in PlatformInitLib makes sense too, probably
best as separate function.

> > Also why limit this to tdx?
> Because I am not sure if other platforms need such operation. So in
> current stage it is limit to tdx.

I think the code should copy over the varstore in case the
SECURE_BOOT_ENABLE option is set.  That is the actual use case and it
makes sense without TDX too.

take care,
  Gerd