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From: "Lendacky, Thomas" <thomas.lendacky@amd.com>
To: devel@edk2.groups.io
Cc: Brijesh Singh <brijesh.singh@amd.com>,
	James Bottomley <jejb@linux.ibm.com>,
	Jordan Justen <jordan.l.justen@intel.com>,
	Laszlo Ersek <lersek@redhat.com>,
	Ard Biesheuvel <ard.biesheuvel@arm.com>
Subject: [PATCH v3 05/15] OvmfPkg/ResetVector: Save the encryption mask at boot time
Date: Thu,  7 Jan 2021 12:48:15 -0600	[thread overview]
Message-ID: <2609724859cf21f0c6d45bc323e94465dca4e621.1610045305.git.thomas.lendacky@amd.com> (raw)
In-Reply-To: <cover.1610045305.git.thomas.lendacky@amd.com>

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

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108

The early assembler code performs validation for some of the SEV-related
information, specifically the encryption bit position. To avoid having to
re-validate the encryption bit position as the system proceeds through its
boot phases, save the validated encryption bit position in the SEV-ES work
area for use by later phases.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 OvmfPkg/Include/Library/MemEncryptSevLib.h |  2 ++
 OvmfPkg/ResetVector/Ia32/PageTables64.asm  | 10 +++++++++-
 OvmfPkg/ResetVector/ResetVector.nasmb      |  1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/OvmfPkg/Include/Library/MemEncryptSevLib.h b/OvmfPkg/Include/Library/MemEncryptSevLib.h
index dc09c61e58bb..a2c70aa550fe 100644
--- a/OvmfPkg/Include/Library/MemEncryptSevLib.h
+++ b/OvmfPkg/Include/Library/MemEncryptSevLib.h
@@ -29,6 +29,8 @@ typedef struct _SEC_SEV_ES_WORK_AREA {
   UINT8    Reserved1[7];
 
   UINT64   RandomData;
+
+  UINT64   EncryptionMask;
 } SEC_SEV_ES_WORK_AREA;
 
 /**
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
index a1771dfdec23..5fae8986d9da 100644
--- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
+++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
@@ -145,7 +145,7 @@ GetSevEncBit:
 
     ; The encryption bit position is always above 31
     sub       ebx, 32
-    jns       SevExit
+    jns       SevSaveMask
 
     ; Encryption bit was reported as 31 or below, enter a HLT loop
 SevEncBitLowHlt:
@@ -153,6 +153,14 @@ SevEncBitLowHlt:
     hlt
     jmp       SevEncBitLowHlt
 
+SevSaveMask:
+    xor       edx, edx
+    bts       edx, ebx
+
+    mov       dword[SEV_ES_WORK_AREA_ENC_MASK], 0
+    mov       dword[SEV_ES_WORK_AREA_ENC_MASK + 4], edx
+    jmp       SevExit
+
 NoSev:
     ;
     ; Perform an SEV-ES sanity check by seeing if a #VC exception occurred.
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
index d3aa87982959..5fbacaed5f9d 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -74,6 +74,7 @@
   %define GHCB_SIZE (FixedPcdGet32 (PcdOvmfSecGhcbSize))
   %define SEV_ES_WORK_AREA (FixedPcdGet32 (PcdSevEsWorkAreaBase))
   %define SEV_ES_WORK_AREA_RDRAND (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 8)
+  %define SEV_ES_WORK_AREA_ENC_MASK (FixedPcdGet32 (PcdSevEsWorkAreaBase) + 16)
   %define SEV_ES_VC_TOP_OF_STACK (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase) + FixedPcdGet32 (PcdOvmfSecPeiTempRamSize))
 %include "Ia32/Flat32ToFlat64.asm"
 %include "Ia32/PageTables64.asm"
-- 
2.30.0


  parent reply	other threads:[~2021-01-07 18:50 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-07 18:48 [PATCH v3 00/15] SEV-ES security mitigations Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 01/15] Ovmf/ResetVector: Simplify and consolidate the SEV features checks Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 02/15] OvmfPkg/Sec: Move SEV-ES SEC workarea definition to common header file Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 03/15] OvmfPkg/ResetVector: Validate the encryption bit position for SEV/SEV-ES Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 04/15] OvmfPkg/ResetVector: Perform a simple SEV-ES sanity check Lendacky, Thomas
2021-01-07 18:48 ` Lendacky, Thomas [this message]
2021-01-07 18:48 ` [PATCH v3 06/15] OvmfPkg/MemEncryptSevLib: Add an interface to retrieve the encryption mask Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 07/15] OvmfPkg: Obtain SEV encryption mask with the new MemEncryptSevLib API Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 08/15] OvmfPkg/AmdSevDxe: Clear encryption bit on PCIe MMCONFIG range Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 09/15] OvmfPkg/VmgExitLib: Check for an explicit DR7 cached value Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 10/15] OvmfPkg/MemEncryptSevLib: Coding style fixes in prep for SEC library Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 11/15] OvmfPkg/MemEncryptSevLib: Make the MemEncryptSevLib available for SEC Lendacky, Thomas
2021-01-07 19:08   ` [edk2-devel] " Laszlo Ersek
2021-01-07 18:48 ` [PATCH v3 12/15] OvmfPkg/MemEncryptSevLib: Address range encryption state interface Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 13/15] OvmfPkg/VmgExitLib: Support nested #VCs Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 14/15] OvmfPkg/PlatformPei: Reserve GHCB backup pages if S3 is supported Lendacky, Thomas
2021-01-07 18:48 ` [PATCH v3 15/15] OvfmPkg/VmgExitLib: Validate #VC MMIO is to un-encrypted memory Lendacky, Thomas
2021-01-07 19:41 ` [edk2-devel] [PATCH v3 00/15] SEV-ES security mitigations Laszlo Ersek
2021-01-07 19:50   ` Lendacky, Thomas

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