[RFC PATCH v5 28/28] OvmfPkg/AmdSev: expose the SNP reserved pages through configuration table

["Brijesh Singh" <brijesh.singh@amd.com>]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

Now that both the secrets and cpuid pages are reserved in the HOB,
extract the location details through fixed PCD and make it available
to the guest OS through the configuration table.

Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/OvmfPkg.dec                           |  1 +
 OvmfPkg/AmdSevDxe/AmdSevDxe.inf               |  7 ++++++
 .../Guid/ConfidentialComputingSecret.h        | 18 +++++++++++++++
 OvmfPkg/AmdSevDxe/AmdSevDxe.c                 | 23 +++++++++++++++++++
 4 files changed, 49 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index afc559d74335..42ad88fc5622 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -122,6 +122,7 @@ [Guids]
   gQemuKernelLoaderFsMediaGuid          = {0x1428f772, 0xb64a, 0x441e, {0xb8, 0xc3, 0x9e, 0xbd, 0xd7, 0xf8, 0x93, 0xc7}}
   gGrubFileGuid                         = {0xb5ae312c, 0xbc8a, 0x43b1, {0x9c, 0x62, 0xeb, 0xb8, 0x26, 0xdd, 0x5d, 0x07}}
   gConfidentialComputingSecretGuid      = {0xadf956ad, 0xe98c, 0x484c, {0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47}}
+  gConfidentialComputingBlobGuid        = {0x067b1f5f, 0xcf26, 0x44c5, {0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42}}
 
 [Ppis]
   # PPI whose presence in the PPI database signals that the TPM base address
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
index 0676fcc5b6a4..ee1f8e4ff09a 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
@@ -42,6 +42,13 @@ [FeaturePcd]
 
 [FixedPcd]
   gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+
+[Guids]
+  gConfidentialComputingBlobGuid
 
 [Pcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
diff --git a/OvmfPkg/Include/Guid/ConfidentialComputingSecret.h b/OvmfPkg/Include/Guid/ConfidentialComputingSecret.h
index 7026fc5b089f..aa1a3b015437 100644
--- a/OvmfPkg/Include/Guid/ConfidentialComputingSecret.h
+++ b/OvmfPkg/Include/Guid/ConfidentialComputingSecret.h
@@ -18,11 +18,29 @@
     { 0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47 }, \
   }
 
+#define CONFIDENTIAL_COMPUTING_BLOB_GUID                \
+  { 0x067b1f5f,                                         \
+    0xcf26,                                             \
+    0x44c5,                                             \
+    { 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42 }, \
+  }
+
 typedef struct {
   UINT64 Base;
   UINT64 Size;
 } CONFIDENTIAL_COMPUTING_SECRET_LOCATION;
 
+typedef struct {
+  UINT32  Header;
+  UINT16  Version;
+  UINT16  Reserved1;
+  UINT64  SecretsPhysicalAddress;
+  UINT32  SecretsSize;
+  UINT64  CpuidPhysicalAddress;
+  UINT32  CpuidLSize;
+} CONFIDENTIAL_COMPUTING_BLOB_LOCATION;
+
 extern EFI_GUID gConfidentialComputingSecretGuid;
+extern EFI_GUID gConfidentialComputingBlobGuid;
 
 #endif // SEV_LAUNCH_SECRET_H_
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
index c66c4e9b9272..c59cc28cf6f5 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.c
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
@@ -17,8 +17,20 @@
 #include <Library/DxeServicesTableLib.h>
 #include <Library/MemEncryptSevLib.h>
 #include <Library/MemoryAllocationLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Guid/ConfidentialComputingSecret.h>
 #include <Library/PcdLib.h>
 
+STATIC CONFIDENTIAL_COMPUTING_BLOB_LOCATION mSnpBootDxeTable = {
+  SIGNATURE_32('A','M','D','E'),
+  1,
+  0,
+  (UINT64)(UINTN) FixedPcdGet32 (PcdOvmfSnpSecretsBase),
+  FixedPcdGet32 (PcdOvmfSnpSecretsSize),
+  (UINT64)(UINTN) FixedPcdGet32 (PcdOvmfSnpCpuidBase),
+  FixedPcdGet32 (PcdOvmfSnpCpuidSize),
+};
+
 EFI_STATUS
 EFIAPI
 AmdSevDxeEntryPoint (
@@ -130,5 +142,16 @@ AmdSevDxeEntryPoint (
     }
   }
 
+  //
+  // If its SEV-SNP active guest then install the CONFIDENTIAL_COMPUTING_BLOB.
+  // It contains the location for both the Secrets and CPUID page.
+  //
+  if (MemEncryptSevSnpIsEnabled ()) {
+    return gBS->InstallConfigurationTable (
+                  &gConfidentialComputingBlobGuid,
+                  &mSnpBootDxeTable
+                  );
+  }
+
   return EFI_SUCCESS;
 }
-- 
2.17.1