Re: [PATCH v14 00/46] SEV-ES guest support

Laszlo Ersek

On 08/07/20 21:38, Lendacky, Thomas wrote:
From: Tom Lendacky <thomas.lendacky@...>

This patch series provides support for running EDK2/OVMF under SEV-ES.

Secure Encrypted Virtualization - Encrypted State (SEV-ES) expands on the
SEV support to protect the guest register state from the hypervisor. See
"AMD64 Architecture Programmer's Manual Volume 2: System Programming",
section "15.35 Encrypted State (SEV-ES)" [1].

In order to allow a hypervisor to perform functions on behalf of a guest,
there is architectural support for notifying a guest's operating system
when certain types of VMEXITs are about to occur. This allows the guest to
selectively share information with the hypervisor to satisfy the requested
function. The notification is performed using a new exception, the VMM
Communication exception (#VC). The information is shared through the
Guest-Hypervisor Communication Block (GHCB) using the VMGEXIT instruction.
The GHCB format and the protocol for using it is documented in "SEV-ES
Guest-Hypervisor Communication Block Standardization" [2].

The main areas of the EDK2 code that are updated to support SEV-ES are
around the exception handling support and the AP boot support.

Exception support is required starting in Sec, continuing through Pei
and into Dxe in order to handle #VC exceptions that are generated. Each
AP requires it's own GHCB page as well as a page to hold values specific
to that AP.

AP booting poses some interesting challenges. The INIT-SIPI-SIPI sequence
is typically used to boot the APs. However, the hypervisor is not allowed
to update the guest registers. The GHCB document [2] talks about how SMP
booting under SEV-ES is performed.

Since the GHCB page must be a shared (unencrypted) page, the processor
must be running in long mode in order for the guest and hypervisor to
communicate with each other. As a result, SEV-ES is only supported under
the X64 architecture.

This series adds a new library requirement for the VmgExitLib library
against the UefiCpuPkg CpuExceptionHandlerLib library and the UefiCpuPkg
MpInitLib library. The edk2-platforms repo requires updates/patches to
add the new library requirement. To accomodate that, this series could be
split between:

patch number 10:
UefiPayloadPkg: Prepare UefiPayloadPkg to use the VmgExitLib library

and patch number 11:
UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC exception

The updates to edk2-platforms can be applied at the split.



These patches are based on commit:
9565ab67c209 ("ShellPkg: smbiosview - Change some type 17 field values format")

A version of the tree can be found at:

Cc: Andrew Fish <afish@...>
Cc: Anthony Perard <anthony.perard@...>
Cc: Ard Biesheuvel <ard.biesheuvel@...>
Cc: Benjamin You <>
Cc: Dandan Bi <>
Cc: Eric Dong <eric.dong@...>
Cc: Guo Dong <guo.dong@...>
Cc: Hao A Wu <hao.a.wu@...>
Cc: Jian J Wang <>
Cc: Jordan Justen <jordan.l.justen@...>
Cc: Julien Grall <julien@...>
Cc: Laszlo Ersek <lersek@...>
Cc: Leif Lindholm <leif@...>
Cc: Liming Gao <liming.gao@...>
Cc: Maurice Ma <>
Cc: Michael D Kinney <michael.d.kinney@...>
Cc: Ray Ni <>

Changes since v13:
- Fixup the AsmRelocateApLoop() call site so IA32 successfully boots APs.
Do this by appending the three new parameters without altering the
original parameter passing order.
- Minor updates to description text and help text to expand the GHCB

Changes since v12:
- Change IA32 VMGEXIT .nasm file to issue an int 3. Depending on the
version of NASM, the "BITS 64" trick to get NASM to recognize the
VMMCALL instruction (VMGEXIT is a REP VMMCALL) caused an error. Since
SEV-ES is X64 only, VMGEXIT should never be called in IA32.

Changes since v11:
- Make the XGETBV and VMGEXIT .nasm files buildable for all environments
and remove the updates that add these instructions to GccInline.c

Changes since v10:
- Fix conflicts around GccInline.c file after moving to latest commit
- Fix conflicts with OVMF PCD values after moving to latest commit

Changes since v9:
- Fixed bit field declarations in the GHCB structure to use UINT32
and not UINT64.
- Fixed a warning produced by VS2019 in the instruction parsing code
by expliciting casting a bit shift to an INT64.
- Sorted section entries in the OVMF VmgExitLib INF file.
- Moved the new Maintainers.txt entry so entries remain sorted.
- Documentation style fixes for return values.
- Miscellaneous code style fixes.

Changes since v8:
- Move IOIO exit info definitions into Ghcb.h file
- Add a macro for calculating IO instruction bytes (IOIO_DATA_BYTES)
- Exception handler support for debug registers
- Moved the DRx register saving changes into the UefiCpuPkg patch for
base #VC support in CpuExceptionHandlerLib.
- OvmfPkg VmgExitLib
- Remove the .uni file
- Update .inf file:
- New file location for VmgExitVcHandler.c
- Add additional Packages and LibraryClasses
- Introduce a header file to hold the #VC instruction parsing related
- Include additional #defines for instruction decoding to replace
hard coded values for things like instruction prefixes and escapes.
- Replace hardcoded CPUID values with values from existing header files
and use existing CR4 definition for accessing CR4 data.
- Change the type used for obtaining data addresses in the instruction
- Switch from INTN to UINT64 and use compiler conversions and casting
to perform the correct address calculation
- ResetVector code:
- Revert some inadvertant changes introduced in v7 for reserving the
SEV-ES work area memory and for checking the status of SEV-ES.
- AP Booting
- Provide support for non-broadcast INIT-SIPI-SIPI AP boot (minimize
code duplication by creating a function to set the AP jump table
vector address).
- Fix file/directory entry in maintainer changes.
- Various coding style fixes
- Commenting, if statements, etc.
- Various documentation style fixes

Changes since v7:
- Reserve the SEV-ES workarea when S3 is enabled
- Fix warnings issued by the Visual Studio compiler
- Create a NULL VmgExitLib instance that is used for VMGEXIT
related operations as well as #VC handling. Then create the full
VmgExitLib support only in OvmfPkg - where it will be used. This
removes a bunch of implementation code from platforms that will
not be using the functionality.
- Remove single use interfaces from the VmgExitLib (VmgMmioWrite
and VmgSetApJumpTable)

Changes since v6:
- Add function comments to all functions, including local functions
- Add function parameter direction to all functions (in/out)
- Add support for MMIO MOVZX/MOVSX instructions
- Ensure the per-CPU variable page remains encrypted
- Coding-style fixes as identified by Ecc

Changes since v5:
- Remove extraneous VmgExitLib usage
- Miscellaneous changes to address feedback (coding style, etc.)

Changes since v4:
- Move the SEV-ES protocol negotiation out of the SEC exception handler
and into the SecMain.c file. As a result:
- Move the SecGhcb related PCDs out of UefiCpuPkg and into OvmfPkg
- Combine SecAMDSevVcHandler.c and PeiDxeAMDSevVcHandler.c into a
single AMDSevVcHandler.c
- Consolidate VmgExitLib usage into common LibraryClasses sections
- Add documentation comments to the VmgExitLib functions

Changes since v3:
- Remove the need for the MP library finalization routine. The AP
jump table address will be held by the hypervisor rather than
communicated via the GHCB MSR. This removes some fragility around
the UEFI to OS transition.
- Rename the SEV-ES RIP reset area to SEV-ES workarea and use it to
communicate the SEV-ES status, so that SEC CPU exception handling is
only established for an SEV-ES guest.
- Fix SMM build breakageAdd around QemuFlashPtrWrite().
- Fix SMM build breakage by adding VC exception support the SMM CPU
exception handling.
- Add memory fencing around the invocation of AsmVmgExit().
- Clarify comments around the SEV-ES AP reset RIP values and usage.
- Move some PCD definitions from MdeModulePkg to UefiCpuPkg.
- Remove the 16-bit code selector definition from MdeModulePkg

Changes since v2:
- Added a way to locate the SEV-ES fixed AP RIP address for starting
AP's to avoid updating the actual flash image (build time location
that is identified with a GUID value).
- Create a VmgExit library to replace static inline functions.
- Move some PCDs to the appropriate packages
- Add support for writing to QEMU flash under SEV-ES
- Add additional MMIO opcode support
- Cleaned up the GHCB MSR CPUID protocol support

Changes since v1:
- Patches reworked to be more specific to the component/area being updated
and order of definition/usage
- Created a library for VMGEXIT-related functions to replace use of inline
- Allocation method for GDT changed from AllocatePool to AllocatePages
- Early caching only enabled for SEV-ES guests
- Ensure AP loop mode set to halt loop mode for SEV-ES guests
- Reserved SEC GHCB-related memory areas when S3 is enabled

Tom Lendacky (46):
MdeModulePkg: Create PCDs to be used in support of SEV-ES
UefiCpuPkg: Create PCD to be used in support of SEV-ES
MdePkg: Add the MSR definition for the GHCB register
MdePkg: Add a structure definition for the GHCB
MdeModulePkg/DxeIplPeim: Support GHCB pages when creating page tables
MdePkg/BaseLib: Add support for the XGETBV instruction
MdePkg/BaseLib: Add support for the VMGEXIT instruction
UefiCpuPkg: Implement library support for VMGEXIT
OvmfPkg: Prepare OvmfPkg to use the VmgExitLib library
UefiPayloadPkg: Prepare UefiPayloadPkg to use the VmgExitLib library
UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC exception
OvmfPkg/VmgExitLib: Implement library support for VmgExitLib in OVMF
OvmfPkg/VmgExitLib: Add support for IOIO_PROT NAE events
OvmfPkg/VmgExitLib: Support string IO for IOIO_PROT NAE events
OvmfPkg/VmgExitLib: Add support for CPUID NAE events
OvmfPkg/VmgExitLib: Add support for MSR_PROT NAE events
OvmfPkg/VmgExitLib: Add support for NPF NAE events (MMIO)
OvmfPkg/VmgExitLib: Add support for WBINVD NAE events
OvmfPkg/VmgExitLib: Add support for RDTSC NAE events
OvmfPkg/VmgExitLib: Add support for RDPMC NAE events
OvmfPkg/VmgExitLib: Add support for INVD NAE events
OvmfPkg/VmgExitLib: Add support for VMMCALL NAE events
OvmfPkg/VmgExitLib: Add support for RDTSCP NAE events
OvmfPkg/VmgExitLib: Add support for MONITOR/MONITORX NAE events
OvmfPkg/VmgExitLib: Add support for MWAIT/MWAITX NAE events
OvmfPkg/VmgExitLib: Add support for DR7 Read/Write NAE events
OvmfPkg/MemEncryptSevLib: Add an SEV-ES guest indicator function
OvmfPkg: Add support to perform SEV-ES initialization
OvmfPkg: Create a GHCB page for use during Sec phase
OvmfPkg/PlatformPei: Reserve GHCB-related areas if S3 is supported
OvmfPkg: Create GHCB pages for use during Pei and Dxe phase
OvmfPkg/PlatformPei: Move early GDT into ram when SEV-ES is enabled
UefiCpuPkg: Create an SEV-ES workarea PCD
OvmfPkg: Reserve a page in memory for the SEV-ES usage
OvmfPkg/PlatformPei: Reserve SEV-ES work area if S3 is supported
OvmfPkg/ResetVector: Add support for a 32-bit SEV check
OvmfPkg/Sec: Add #VC exception handling for Sec phase
OvmfPkg/Sec: Enable cache early to speed up booting
OvmfPkg/QemuFlashFvbServicesRuntimeDxe: Bypass flash detection with
UefiCpuPkg: Add a 16-bit protected mode code segment descriptor
UefiCpuPkg/MpInitLib: Add CPU MP data flag to indicate if SEV-ES is
UefiCpuPkg: Allow AP booting under SEV-ES
OvmfPkg: Use the SEV-ES work area for the SEV-ES AP reset vector
OvmfPkg: Move the GHCB allocations into reserved memory
UefiCpuPkg/MpInitLib: Prepare SEV-ES guest APs for OS use
Maintainers.txt: Add reviewers for the OvmfPkg SEV-related files

MdeModulePkg/MdeModulePkg.dec | 9 +
OvmfPkg/OvmfPkg.dec | 9 +
UefiCpuPkg/UefiCpuPkg.dec | 17 +
OvmfPkg/OvmfPkgIa32.dsc | 6 +
OvmfPkg/OvmfPkgIa32X64.dsc | 6 +
OvmfPkg/OvmfPkgX64.dsc | 6 +
OvmfPkg/OvmfXen.dsc | 1 +
UefiCpuPkg/UefiCpuPkg.dsc | 2 +
UefiPayloadPkg/UefiPayloadPkgIa32.dsc | 2 +
UefiPayloadPkg/UefiPayloadPkgIa32X64.dsc | 2 +
OvmfPkg/OvmfPkgX64.fdf | 9 +
MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf | 2 +
MdePkg/Library/BaseLib/BaseLib.inf | 4 +
OvmfPkg/Library/VmgExitLib/VmgExitLib.inf | 36 +
OvmfPkg/PlatformPei/PlatformPei.inf | 9 +
.../FvbServicesRuntimeDxe.inf | 2 +
OvmfPkg/ResetVector/ResetVector.inf | 8 +
OvmfPkg/Sec/SecMain.inf | 4 +
.../DxeCpuExceptionHandlerLib.inf | 1 +
.../PeiCpuExceptionHandlerLib.inf | 1 +
.../SecPeiCpuExceptionHandlerLib.inf | 1 +
.../SmmCpuExceptionHandlerLib.inf | 1 +
.../Xcode5SecPeiCpuExceptionHandlerLib.inf | 1 +
UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf | 4 +
UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf | 4 +
.../Library/VmgExitLibNull/VmgExitLibNull.inf | 27 +
.../Core/DxeIplPeim/X64/VirtualMemory.h | 12 +-
MdePkg/Include/Library/BaseLib.h | 31 +
MdePkg/Include/Register/Amd/Fam17Msr.h | 46 +
MdePkg/Include/Register/Amd/Ghcb.h | 166 ++
.../IndustryStandard/InstructionParsing.h | 83 +
OvmfPkg/Include/Library/MemEncryptSevLib.h | 12 +
.../QemuFlash.h | 13 +
UefiCpuPkg/CpuDxe/CpuGdt.h | 4 +-
UefiCpuPkg/Include/Library/VmgExitLib.h | 103 +
UefiCpuPkg/Library/MpInitLib/MpLib.h | 68 +-
.../Core/DxeIplPeim/Ia32/DxeLoadFunc.c | 4 +-
.../Core/DxeIplPeim/X64/DxeLoadFunc.c | 11 +-
.../Core/DxeIplPeim/X64/VirtualMemory.c | 57 +-
.../MemEncryptSevLibInternal.c | 75 +-
OvmfPkg/Library/VmgExitLib/VmgExitLib.c | 159 ++
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 1716 +++++++++++++++++
OvmfPkg/PlatformPei/AmdSev.c | 89 +
OvmfPkg/PlatformPei/MemDetect.c | 43 +
.../QemuFlash.c | 23 +-
.../QemuFlashDxe.c | 40 +
.../QemuFlashSmm.c | 16 +
OvmfPkg/Sec/SecMain.c | 188 +-
UefiCpuPkg/CpuDxe/CpuGdt.c | 8 +-
.../CpuExceptionCommon.c | 10 +-
.../PeiDxeSmmCpuException.c | 20 +-
.../SecPeiCpuException.c | 19 +
UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 120 +-
UefiCpuPkg/Library/MpInitLib/MpLib.c | 337 +++-
UefiCpuPkg/Library/MpInitLib/PeiMpLib.c | 19 +
.../Library/VmgExitLibNull/VmgExitLibNull.c | 121 ++
UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c | 2 +-
Maintainers.txt | 10 +
MdeModulePkg/MdeModulePkg.uni | 8 +
MdePkg/Library/BaseLib/Ia32/VmgExit.nasm | 38 +
MdePkg/Library/BaseLib/Ia32/XGetBv.nasm | 31 +
MdePkg/Library/BaseLib/X64/VmgExit.nasm | 32 +
MdePkg/Library/BaseLib/X64/XGetBv.nasm | 34 +
OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm | 100 +
OvmfPkg/ResetVector/Ia32/PageTables64.asm | 351 +++-
OvmfPkg/ResetVector/ResetVector.nasmb | 20 +
.../X64/ExceptionHandlerAsm.nasm | 17 +
.../X64/Xcode5ExceptionHandlerAsm.nasm | 17 +
UefiCpuPkg/Library/MpInitLib/Ia32/ | 2 +-
.../Library/MpInitLib/Ia32/MpFuncs.nasm | 20 +-
UefiCpuPkg/Library/MpInitLib/X64/ | 4 +-
UefiCpuPkg/Library/MpInitLib/X64/MpFuncs.nasm | 369 +++-
.../Library/VmgExitLibNull/VmgExitLibNull.uni | 15 +
.../ResetVector/Vtf0/Ia16/Real16ToFlat32.asm | 9 +
UefiCpuPkg/UefiCpuPkg.uni | 11 +
75 files changed, 4777 insertions(+), 100 deletions(-)
create mode 100644 OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
create mode 100644 UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.inf
create mode 100644 MdePkg/Include/Register/Amd/Ghcb.h
create mode 100644 OvmfPkg/Include/IndustryStandard/InstructionParsing.h
create mode 100644 UefiCpuPkg/Include/Library/VmgExitLib.h
create mode 100644 OvmfPkg/Library/VmgExitLib/VmgExitLib.c
create mode 100644 OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
create mode 100644 UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.c
create mode 100644 MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
create mode 100644 MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
create mode 100644 MdePkg/Library/BaseLib/X64/VmgExit.nasm
create mode 100644 MdePkg/Library/BaseLib/X64/XGetBv.nasm
create mode 100644 OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm
create mode 100644 UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.uni
For all patches except #10 ("UefiPayloadPkg: Prepare UefiPayloadPkg to
use the VmgExitLib library") and #46 ("Maintainers.txt: Add reviewers
for the OvmfPkg SEV-related files"):

Regression-tested-by: Laszlo Ersek <lersek@...>


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