[edk2-devel] [RFC PATCH 18/19] OvmfPkg/MemEncryptSevLib: Validate the memory during set or clear enc attribute
Brijesh Singh
brijesh.singh at amd.com
Wed Mar 24 15:32:14 UTC 2021
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275
The MemEncryptSev{Set,Clear}PageEncMask() functions are used to set or
clear the memory encryption attribute in the page table. When SEV-SNP is
active, we also need to validate or invalidate the pages and update the
RMP entry.
Before clearing the encryption attribute we need to invalidate the memory,
and then make the page shared in the RMP entry. Similarly, after setting
the encryption attribute in the page table, we add the memory as private
in the RMP entry and validate it.
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>
Signed-off-by: Brijesh Singh <brijesh.singh at amd.com>
---
OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf | 3 ++
OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf | 1 +
OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeSnpSetPageState.c | 32 +++++++++++++++++
OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c | 36 ++++++++++++++++++--
OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpSetPageState.h | 27 +++++++++++++++
5 files changed, 97 insertions(+), 2 deletions(-)
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
index f2e162d680..fa8f7719a7 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLib.inf
@@ -36,6 +36,8 @@
[Sources.X64]
X64/MemEncryptSevLib.c
X64/PeiDxeVirtualMemory.c
+ X64/SnpPageStateChangeInternal.c
+ X64/PeiDxeSnpSetPageState.c
X64/VirtualMemory.c
X64/VirtualMemory.h
@@ -49,6 +51,7 @@
DebugLib
MemoryAllocationLib
PcdLib
+ VmgExitLib
[FeaturePcd]
gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
index cb9dd2bb21..d16ec44954 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
@@ -37,6 +37,7 @@
[Sources.X64]
X64/MemEncryptSevLib.c
X64/PeiDxeVirtualMemory.c
+ X64/PeiDxeSnpSetPageState.c
X64/PeiSnpSystemRamValidate.c
X64/SnpPageStateTrack.c
X64/SnpPageStateChangeInternal.c
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeSnpSetPageState.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeSnpSetPageState.c
new file mode 100644
index 0000000000..0a3d58ac22
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeSnpSetPageState.c
@@ -0,0 +1,32 @@
+/** @file
+
+ SEV-SNP Page Validation functions.
+
+ Copyright (c) 2020 - 2021, AMD Incorporated. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Library/BaseLib.h>
+
+#include "PeiSnpPageStateChange.h"
+
+VOID
+SnpSetMemoryPrivate (
+ IN PHYSICAL_ADDRESS PhysicalAddress,
+ IN UINTN Length
+ )
+{
+ SetPageStateInternal (PhysicalAddress, EFI_SIZE_TO_PAGES (Length), SevSnpPagePrivate, FALSE);
+}
+
+VOID
+SnpSetMemoryShared (
+ IN PHYSICAL_ADDRESS PhysicalAddress,
+ IN UINTN Length
+ )
+{
+ SetPageStateInternal (PhysicalAddress, EFI_SIZE_TO_PAGES (Length), SevSnpPageShared, FALSE);
+}
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
index 33d9bafe9f..26d363d427 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
@@ -17,6 +17,7 @@
#include <Register/Cpuid.h>
#include "VirtualMemory.h"
+#include "SnpSetPageState.h"
STATIC BOOLEAN mAddressEncMaskChecked = FALSE;
STATIC UINT64 mAddressEncMask;
@@ -700,22 +701,34 @@ SetMemoryEncDec (
UINT64 AddressEncMask;
BOOLEAN IsWpEnabled;
RETURN_STATUS Status;
+ BOOLEAN NeedPageStateChange;
+ PHYSICAL_ADDRESS OrigPhysicalAddress;
+ UINTN OrigLength;
//
// Set PageMapLevel4Entry to suppress incorrect compiler/analyzer warnings.
//
PageMapLevel4Entry = NULL;
+ //
+ // When SEV-SNP is active, before clearing the encryption attribute from
+ // the page table we also need to update the RMP entry for the memory
+ // region to make the region shared. And after setting the encryption
+ // attribute, the region must be made private in the RMP table.
+ //
+ NeedPageStateChange = MemEncryptSevSnpIsEnabled ();
+
DEBUG ((
DEBUG_VERBOSE,
- "%a:%a: Cr3Base=0x%Lx Physical=0x%Lx Length=0x%Lx Mode=%a CacheFlush=%u\n",
+ "%a:%a: Cr3Base=0x%Lx Physical=0x%Lx Length=0x%Lx Mode=%a CacheFlush=%u Rmpupdate=%u\n",
gEfiCallerBaseName,
__FUNCTION__,
Cr3BaseAddress,
PhysicalAddress,
(UINT64)Length,
(Mode == SetCBit) ? "Encrypt" : "Decrypt",
- (UINT32)CacheFlush
+ (UINT32)CacheFlush,
+ (UINT32)NeedPageStateChange
));
//
@@ -749,6 +762,18 @@ SetMemoryEncDec (
DisableReadOnlyPageWriteProtect ();
}
+ //
+ // Make the RMP updates before clearing the encryption attribute in the page table.
+ //
+ if (NeedPageStateChange && (Mode == ClearCBit)) {
+ SnpSetMemoryShared (PhysicalAddress, Length);
+ }
+
+ //
+ // Save the values, we need it later during the Page state change.
+ //
+ OrigPhysicalAddress = PhysicalAddress;
+ OrigLength = Length;
Status = EFI_SUCCESS;
while (Length != 0)
@@ -923,6 +948,13 @@ SetMemoryEncDec (
//
CpuFlushTlb();
+ //
+ // Make the RMP updates after setting the encryption attribute in the page table.
+ //
+ if (NeedPageStateChange && (Mode == SetCBit)) {
+ SnpSetMemoryPrivate (OrigPhysicalAddress, OrigLength);
+ }
+
Done:
//
// Restore page table write protection, if any.
diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpSetPageState.h b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpSetPageState.h
new file mode 100644
index 0000000000..0b29bad612
--- /dev/null
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpSetPageState.h
@@ -0,0 +1,27 @@
+/** @file
+
+ SEV-SNP Page Validation functions.
+
+ Copyright (c) 2020 - 2021, AMD Incorporated. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef PEI_DXE_SNP_PAGE_STATE_INTERNAL_H_
+#define PEI_DXE_SNP_PAGE_STATE_INTERNAL_H_
+
+#include "../SnpPageStateChange.h"
+
+VOID
+SnpSetMemoryPrivate (
+ IN PHYSICAL_ADDRESS PhysicalAddress,
+ IN UINTN Length
+ );
+
+VOID
+SnpSetMemoryShared (
+ IN PHYSICAL_ADDRESS PhysicalAddress,
+ IN UINTN Length
+ );
+#endif
--
2.17.1
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#73234): https://edk2.groups.io/g/devel/message/73234
Mute This Topic: https://groups.io/mt/81584595/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-
More information about the edk2-devel-archive
mailing list