Re: [RFC PATCH v1 4/5] OvmfPkg/BaseIoLibIntrinsic: import BaseIoLibIntrinsic package

["Duran, Leo" <leo.duran@amd.com>]

OK, what I'm hearing is:
- Let's leave the Fifo routines in BaseIoLib (as we currently have)
- And let's add the SEV checks to BaseIoLib, so that OvmPkg (et al) can consume it as-is

If so, I could put a patch-set together for that... Please confirm.
BTW, I'd try to minimize the need for CPUID (e.g., check it once and cache the result)

Leo

> -----Original Message-----
> From: Gao, Liming [mailto:liming.gao@intel.com]
> Sent: Wednesday, March 08, 2017 7:48 PM
> To: Justen, Jordan L <jordan.l.justen@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>; edk2-devel@lists.01.org; Brijesh Singh
> <brijesh.ksingh@gmail.com>; Laszlo Ersek <lersek@redhat.com>
> Cc: Lendacky, Thomas <Thomas.Lendacky@amd.com>; Duran, Leo
> <leo.duran@amd.com>; brijesh.sing@amd.com
> Subject: RE: [RFC PATCH v1 4/5] OvmfPkg/BaseIoLibIntrinsic: import
> BaseIoLibIntrinsic package
> 
> 
> 
> > -----Original Message-----
> > From: Justen, Jordan L
> > Sent: Thursday, March 9, 2017 2:59 AM
> > To: Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
> > <michael.d.kinney@intel.com>; edk2-devel@lists.01.org; Brijesh Singh
> > <brijesh.ksingh@gmail.com>; Laszlo Ersek <lersek@redhat.com>
> > Cc: Thomas.Lendacky@amd.com; leo.duran@amd.com;
> brijesh.sing@amd.com
> > Subject: RE: [RFC PATCH v1 4/5] OvmfPkg/BaseIoLibIntrinsic: import
> > BaseIoLibIntrinsic package
> >
> > On 2017-03-08 07:41:58, Gao, Liming wrote:
> > >
> > > >-----Original Message-----
> > > >From: Justen, Jordan L
> > >
> > > >One other thought is, should we consider a DxeSmm alternative .inf
> > > >for BaseIoLibIntrinsic.inf? In that case we could use a global
> > > >variable to help out. Maybe this could prevent the concern that
> > > >might drive a new PCD to be added?
> > > >
> > > >-Jordan
> > > Current patch has stored the check state into data section. In PEI
> > > phase, the data section can't be written. So, every call will check
> > > CpuId. In DXE and SMM phase, the data section can be written. The
> > > first call will cache the check state. So, no DxeSmm INF is
> > > required.
> > >
> >
> > I don't think we can attempt to write a variable to memory in generic
> > SEC/PEI code. Some flash memory treat memory writes as an I/O for
> > programming purposes. I think we added
> > PcdGuidedExtractHandlerTableAddress for this reason. This is why I
> > suggested that maybe we could add a DXE/SMM .inf where we could
> assume
> > writeable global variables exit.
> >
> > -Jordan
> 
> I get your point. So, I suggest to always check SEV in BaseIoLib. If people
> meet with the performance issue, DXE/SMM version IoLib can be added
> later.
>