Re: [PATCH v6 00/29] Add AMD Secure Nested Paging (SEV-SNP) support

["Min Xu" <min.m.xu@intel.com>]

On September 7, 2021 10:37 AM, Jiewen Yao wrote:
> 
> 0008-UefiCpuPkg-Define-the-SEV-SNP-specific-dynamic-PCDs
> I really don't like the idea to use BOOL PcdSevEsIsEnabled and
> PcdSevSnpIsEnabled.
> Can we define *one* PCD - such as PcdConfidentialComputingCategory?
> We can assign range 0x0000~0xFFFF to AMD SEV, 0x10000~0x1FFFF to Intel TDX.
> Then SEV=0x0000, SEV-ES=0x0001, SEV-SNP=0x0002, and TDX=0x10000 later.
> I really don't want to keep adding PCD endlessly in the future, like
> PcdSevXXXIsEnabled, PcdSevYYYIsEnabled, PcdTdxIsEnabled, PcdTdx20Enabled,
> PcdTdx30Enabled, ......
> 
We have CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER definition in OvmfPkg\Include\WorkArea.h like below:
typedef struct _CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER {
  UINT8                   GuestType;   // 0 - legacy guest, 1 - SEV guest, 2 - tdx guest
  UINT8                   Reserved1[3];
} CONFIDENTIAL_COMPUTING_WORK_AREA_HEADER;

Can we define the PcdConfidentialComputingCategory like below:
  ## This dynamic PCD indicates the Confidential Computing Category
  #  [7:0]     Confidential Computing Category  (0 - Non-Cc, 1 - AmdSev, 2 - IntelTdx)
  #  [15:8]   Sub-Category (defined by each vendor, SEV-ES, SEV-SNP, or TDX-1.0, TDX-2.0, etc)
  #  [31:16] Reserved
  # @Prompt Confidential Computing Category
  gUefiCpuPkgTokenSpaceGuid.PcdConfidentialComputingCategory|0|UINT32|0x60000018

Thanks!
Min