Re: Subject: [PATCH ovmf 2/5] MdePkg: Add AMD SEV features to PcdConfidentialComputingGuestAttr

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

On Fri, Dec 02, 2022 at 11:26:56PM +1100, Alexey Kardashevskiy wrote:
> 
> 
> On 2/12/22 01:47, Tom Lendacky wrote:
> > Added the subject as somehow it didn't get set.
> > 
> > On 11/30/22 20:35, Alexey Kardashevskiy wrote:
> > > Date: Tue, 22 Nov 2022 16:12:55 +1100
> > > Subject: [PATCH ovmf 2/5] MdePkg: Add AMD SEV features to
> > >   PcdConfidentialComputingGuestAttr
> > > 
> > > PcdConfidentialComputingGuestAttr so far only contained an SEV mode bit
> > > but there are more other features which do not translate to levels
> > > such as DebugSwap or SecureTsc.
> > > 
> > > This adds the features mask and the DebugSwap feature bit to a PCD.
> > > 
> > > Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
> > > ---
> > >   MdePkg/Include/ConfidentialComputingGuestAttr.h | 5 ++++-
> > >   1 file changed, 4 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/MdePkg/Include/ConfidentialComputingGuestAttr.h
> > > b/MdePkg/Include/ConfidentialComputingGuestAttr.h
> > > index 44e6df800207..1fd09a51ea52 100644
> > > --- a/MdePkg/Include/ConfidentialComputingGuestAttr.h
> > > +++ b/MdePkg/Include/ConfidentialComputingGuestAttr.h
> > > @@ -26,12 +26,15 @@ typedef enum {
> > >     CCAttrAmdSev    = 0x100,
> > >     CCAttrAmdSevEs  = 0x101,
> > >     CCAttrAmdSevSnp = 0x102,
> > > +  CCAttrAmdSevFeatureMask      = 0xffff0000,
> > 
> > The PCD for this is 64-bits, should this be 0xffffffffffff0000?
> 
> True but does not that really depend on how greedy I am? :) For now I like
> 16bits and leave the rest for everyone else.

If we want add feature bits to that PCD it should IMHO not be
AmdSev-specific, i.e. we should have something along the lines of:

CCAttrTypeMask     0x000000000000ffff
CCAttrFeatureMask  0xffffffffffff0000

Alternatively use another pcd for the feature bits.

take care,
  Gerd