[edk2-devel] [PATCH v14 31/32] OvmfPkg/AmdSev: expose the SNP reserved pages through configuration table

[Brijesh Singh via groups.io]

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 at amd.com>
Cc: James Bottomley <jejb at linux.ibm.com>
Cc: Min Xu <min.m.xu at intel.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Tom Lendacky <thomas.lendacky at amd.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Ard Biesheuvel <ardb+tianocore at kernel.org>
Cc: Erdem Aktas <erdemaktas at google.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Acked-by: Gerd Hoffmann <kraxel at redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh at 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 c22b846cd663..769bef0ffa12 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..b328310fd0c2
--- /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 be26dde71f9d..662d3c4ccb0f 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 (
@@ -135,5 +147,16 @@ 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



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