[RFC PATCH 03/28] OvmfPkg/MemEncryptSevLib: Add an SEV-ES guest indicator function

Lendacky, Thomas
 

From: Tom Lendacky <thomas.lendacky@...>

Create a function that can be used to determine if the VM is running
as an SEV-ES guest.

Signed-off-by: Tom Lendacky <thomas.lendacky@...>
---
OvmfPkg/Include/Library/MemEncryptSevLib.h | 12 +++
.../MemEncryptSevLibInternal.c | 77 ++++++++++++-------
2 files changed, 62 insertions(+), 27 deletions(-)

diff --git a/OvmfPkg/Include/Library/MemEncryptSevLib.h b/OvmfPkg/Include/Library/MemEncryptSevLib.h
index 64dd6977b0f8..a50a0de9c870 100644
--- a/OvmfPkg/Include/Library/MemEncryptSevLib.h
+++ b/OvmfPkg/Include/Library/MemEncryptSevLib.h
@@ -13,6 +13,18 @@

#include <Base.h>

+/**
+ Returns a boolean to indicate whether SEV-ES is enabled
+
+ @retval TRUE SEV-ES is enabled
+ @retval FALSE SEV-ES is not enabled
+**/
+BOOLEAN
+EFIAPI
+MemEncryptSevEsIsEnabled (
+ VOID
+ );
+
/**
Returns a boolean to indicate whether SEV is enabled

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
index 96a66e373f11..9c1d68e017fe 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/MemEncryptSevLibInternal.c
@@ -20,19 +20,17 @@
#include <Uefi/UefiBaseType.h>

STATIC BOOLEAN mSevStatus = FALSE;
+STATIC BOOLEAN mSevEsStatus = FALSE;
STATIC BOOLEAN mSevStatusChecked = FALSE;

/**

- Returns a boolean to indicate whether SEV is enabled
-
- @retval TRUE SEV is enabled
- @retval FALSE SEV is not enabled
+ Reads and sets the status of SEV features
**/
STATIC
-BOOLEAN
+VOID
EFIAPI
-InternalMemEncryptSevIsEnabled (
+InternalMemEncryptSevStatus (
VOID
)
{
@@ -56,32 +54,57 @@ InternalMemEncryptSevIsEnabled (
//
Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
if (Msr.Bits.SevBit) {
- return TRUE;
+ mSevStatus = TRUE;
+ }
+
+ if (Eax.Bits.SevEsBit) {
+ //
+ // Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)
+ //
+ if (Msr.Bits.SevEsBit) {
+ mSevEsStatus = TRUE;
+ }
}
}
}

- return FALSE;
-}
-
-/**
- Returns a boolean to indicate whether SEV is enabled
-
- @retval TRUE SEV is enabled
- @retval FALSE SEV is not enabled
-**/
-BOOLEAN
-EFIAPI
-MemEncryptSevIsEnabled (
- VOID
- )
-{
- if (mSevStatusChecked) {
- return mSevStatus;
- }
-
- mSevStatus = InternalMemEncryptSevIsEnabled();
mSevStatusChecked = TRUE;
+}
+
+/**
+ Returns a boolean to indicate whether SEV-ES is enabled
+
+ @retval TRUE SEV-ES is enabled
+ @retval FALSE SEV-ES is not enabled
+**/
+BOOLEAN
+EFIAPI
+MemEncryptSevEsIsEnabled (
+ VOID
+ )
+{
+ if (!mSevStatusChecked) {
+ InternalMemEncryptSevStatus();
+ }
+
+ return mSevEsStatus;
+}
+
+/**
+ Returns a boolean to indicate whether SEV is enabled
+
+ @retval TRUE SEV is enabled
+ @retval FALSE SEV is not enabled
+**/
+BOOLEAN
+EFIAPI
+MemEncryptSevIsEnabled (
+ VOID
+ )
+{
+ if (!mSevStatusChecked) {
+ InternalMemEncryptSevStatus();
+ }

return mSevStatus;
}
--
2.17.1

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