[edk2-devel] [PATCH RFC v3 20/22] OvmfPkg/AmdSev: expose the SNP reserved pages through configuration table

[Brijesh Singh]

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 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: Laszlo Ersek <lersek at redhat.com>
Cc: Erdem Aktas <erdemaktas at google.com>
Signed-off-by: Brijesh Singh <brijesh.singh at amd.com>
---
 OvmfPkg/OvmfPkg.dec                           |  1 +
 OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf        |  4 ++++
 .../Guid/ConfidentialComputingSecret.h        | 18 +++++++++++++++
 OvmfPkg/AmdSev/SecretDxe/SecretDxe.c          | 22 +++++++++++++++++++
 4 files changed, 45 insertions(+)

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 4da2d2de9df0..89476c6a68d2 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -126,6 +126,7 @@ [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/AmdSev/SecretDxe/SecretDxe.inf b/OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf
index 40bda7ff846c..d15194b368f5 100644
--- a/OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf
+++ b/OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf
@@ -23,13 +23,17 @@ [Packages]
   MdePkg/MdePkg.dec
 
 [LibraryClasses]
+  MemEncryptSevLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
 
 [Guids]
   gConfidentialComputingSecretGuid
+  gConfidentialComputingBlobGuid
 
 [FixedPcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpCpuidSize
   gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase
   gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize
 
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/AmdSev/SecretDxe/SecretDxe.c b/OvmfPkg/AmdSev/SecretDxe/SecretDxe.c
index 308022b5b25e..0c0f511d4ca0 100644
--- a/OvmfPkg/AmdSev/SecretDxe/SecretDxe.c
+++ b/OvmfPkg/AmdSev/SecretDxe/SecretDxe.c
@@ -6,6 +6,7 @@
 **/
 #include <PiDxe.h>
 #include <Library/UefiBootServicesTableLib.h>
+#include <Library/MemEncryptSevLib.h>
 #include <Guid/ConfidentialComputingSecret.h>
 
 STATIC CONFIDENTIAL_COMPUTING_SECRET_LOCATION mSecretDxeTable = {
@@ -13,6 +14,16 @@ STATIC CONFIDENTIAL_COMPUTING_SECRET_LOCATION mSecretDxeTable = {
   FixedPcdGet32 (PcdSevLaunchSecretSize),
 };
 
+STATIC CONFIDENTIAL_COMPUTING_BLOB_LOCATION mSnpBootDxeTable = {
+  SIGNATURE_32('A','M','D','E'),
+  1,
+  0,
+  (UINT64)(UINTN) FixedPcdGet32 (PcdSevLaunchSecretBase),
+  FixedPcdGet32 (PcdSevLaunchSecretSize),
+  (UINT64)(UINTN) FixedPcdGet32 (PcdOvmfSnpCpuidBase),
+  FixedPcdGet32 (PcdOvmfSnpCpuidSize),
+};
+
 EFI_STATUS
 EFIAPI
 InitializeSecretDxe(
@@ -20,6 +31,17 @@ InitializeSecretDxe(
   IN EFI_SYSTEM_TABLE     *SystemTable
   )
 {
+  //
+  // 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 gBS->InstallConfigurationTable (
                 &gConfidentialComputingSecretGuid,
                 &mSecretDxeTable
-- 
2.17.1



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