[PATCH v8 31/32] 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: Michael Roth <michael.roth@amd.com>
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: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/OvmfPkg.dec                           |  1 +
 OvmfPkg/AmdSevDxe/AmdSevDxe.inf               |  7 ++++
 .../Guid/ConfidentialComputingSevSnpBlob.h    | 33 +++++++++++++++++++
 OvmfPkg/AmdSevDxe/AmdSevDxe.c                 | 23 +++++++++++++
 4 files changed, 64 insertions(+)
 create mode 100644 OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 052784c18864..aabe81d5c63e 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -124,6 +124,7 @@ [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}}
+  gConfidentialComputingSevSnpBlobGuid  = {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..9acf860cf25e 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
@@ -42,6 +42,13 @@ [FeaturePcd]
 
 [FixedPcd]
   gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+
+[Guids]
+  gConfidentialComputingSevSnpBlobGuid
 
 [Pcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
diff --git a/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h b/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h
new file mode 100644
index 000000000000..c98e7a1dcccd
--- /dev/null
+++ b/OvmfPkg/Include/Guid/ConfidentialComputingSevSnpBlob.h
@@ -0,0 +1,33 @@
+ /** @file
+   UEFI Configuration Table for exposing the SEV-SNP launch blob.
+
+   Copyright (c) 2021, Advanced Micro Devices Inc. All right reserved.
+
+   SPDX-License-Identifier: BSD-2-Clause-Patent
+ **/
+
+#ifndef CONFIDENTIAL_COMPUTING_SEV_SNP_BLOB_H_
+#define CONFIDENTIAL_COMPUTING_SEV_SNP_BLOB_H_
+
+#include <Uefi/UefiBaseType.h>
+
+#define CONFIDENTIAL_COMPUTING_SNP_BLOB_GUID            \
+  { 0x067b1f5f,                                         \
+    0xcf26,                                             \
+    0x44c5,                                             \
+    { 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42 }, \
+  }
+
+typedef struct {
+  UINT32  Header;
+  UINT16  Version;
+  UINT16  Reserved1;
+  UINT64  SecretsPhysicalAddress;
+  UINT32  SecretsSize;
+  UINT64  CpuidPhysicalAddress;
+  UINT32  CpuidLSize;
+} CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION;
+
+extern EFI_GUID gConfidentialComputingSevSnpBlobGuid;
+
+#endif
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
index c66c4e9b9272..6e1ba35e02b8 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/ConfidentialComputingSevSnpBlob.h>
 #include <Library/PcdLib.h>
 
+STATIC CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION mSnpBootDxeTable = {
+  SIGNATURE_32('A','M','D','E'),
+  1,
+  0,
+  (UINT64)(UINTN) FixedPcdGet32 (PcdOvmfSnpSecretsBase),
+  FixedPcdGet32 (PcdOvmfSnpSecretsSize),
+  (UINT64)(UINTN) FixedPcdGet32 (PcdOvmfCpuidBase),
+  FixedPcdGet32 (PcdOvmfCpuidSize),
+};
+
 EFI_STATUS
 EFIAPI
 AmdSevDxeEntryPoint (
@@ -130,5 +142,16 @@ AmdSevDxeEntryPoint (
     }
   }
 
+  //
+  // If its SEV-SNP active guest then install the CONFIDENTIAL_COMPUTING_SEV_SNP_BLOB.
+  // It contains the location for both the Secrets and CPUID page.
+  //
+  if (MemEncryptSevSnpIsEnabled ()) {
+    return gBS->InstallConfigurationTable (
+                  &gConfidentialComputingSevSnpBlobGuid,
+                  &mSnpBootDxeTable
+                  );
+  }
+
   return EFI_SUCCESS;
 }
-- 
2.25.1