Hi Tom,

On 08/07/20 21:38, Lendacky, Thomas wrote:

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

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

VMGEXIT is a new instruction used for Hypervisor/Guest communication when
running as an SEV-ES guest. A VMGEXIT will cause an automatic exit (AE)
to occur, resulting in a #VMEXIT with an exit code value of 0x403.

Since SEV-ES is only supported in X64, provide the necessary X64 support
to execute the VMGEXIT instruction, which is coded as "rep vmmcall". For
IA32, since "vmmcall" is not supported in NASM 32-bit mode and VMGEXIT
should never be called, provide a stub implementation that is identical
to CpuBreakpoint().

Cc: Michael D Kinney <michael.d.kinney@...>
Cc: Liming Gao <liming.gao@...>
Reviewed-by: Liming Gao <liming.gao@...>
Signed-off-by: Tom Lendacky <thomas.lendacky@...>
---
MdePkg/Library/BaseLib/BaseLib.inf | 2 ++
MdePkg/Include/Library/BaseLib.h | 14 +++++++++
MdePkg/Library/BaseLib/Ia32/VmgExit.nasm | 38 ++++++++++++++++++++++++
MdePkg/Library/BaseLib/X64/VmgExit.nasm | 32 ++++++++++++++++++++
4 files changed, 86 insertions(+)
create mode 100644 MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
create mode 100644 MdePkg/Library/BaseLib/X64/VmgExit.nasm

this patch is identical to the one in v13, but you forgot to pick up my:

Reviewed-by: Laszlo Ersek <lersek@...>

from:

https://edk2.groups.io/g/devel/message/63568
http://mid.mail-archive.com/98ff9331-c73b-07f9-de49-f08365c6e003@redhat.com

Liming, when you push this series, please add my R-b to the commit
message on this patch.

Thanks
Laszlo

diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf
index 3b93b5db8d24..3b85c56c3c03 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -184,6 +184,7 @@ [Sources.Ia32]
Ia32/DisableCache.nasm| GCC
Ia32/RdRand.nasm
Ia32/XGetBv.nasm
+ Ia32/VmgExit.nasm

Ia32/DivS64x64Remainder.c
Ia32/InternalSwitchStack.c | MSFT
@@ -317,6 +318,7 @@ [Sources.X64]
X64/DisablePaging64.nasm
X64/RdRand.nasm
X64/XGetBv.nasm
+ X64/VmgExit.nasm
ChkStkGcc.c | GCC

[Sources.EBC]
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 7edf0051a0a0..04fb329eaabb 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -7848,6 +7848,20 @@ AsmXGetBv (
);


+/**
+ Executes a VMGEXIT instruction (VMMCALL with a REP prefix)
+
+ Executes a VMGEXIT instruction. This function is only available on IA-32 and
+ x64.
+
+**/
+VOID
+EFIAPI
+AsmVmgExit (
+ VOID
+ );
+
+
/**
Patch the immediate operand of an IA32 or X64 instruction such that the byte,
word, dword or qword operand is encoded at the end of the instruction's
diff --git a/MdePkg/Library/BaseLib/Ia32/VmgExit.nasm b/MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
new file mode 100644
index 000000000000..69f7fbf3506a
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
@@ -0,0 +1,38 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+; VmgExit.Asm
+;
+; Abstract:
+;
+; AsmVmgExit function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+ SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; AsmVmgExit (
+; VOID
+; );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmVmgExit)
+ASM_PFX(AsmVmgExit):
+;
+; NASM doesn't support the vmmcall instruction in 32-bit mode and NASM versions
+; before 2.12 cannot translate the 64-bit "rep vmmcall" instruction into elf32
+; format. Given that VMGEXIT does not make sense on IA32, provide a stub
+; implementation that is identical to CpuBreakpoint(). In practice, AsmVmgExit()
+; should never be called on IA32.
+;
+ int 3
+ ret
+
diff --git a/MdePkg/Library/BaseLib/X64/VmgExit.nasm b/MdePkg/Library/BaseLib/X64/VmgExit.nasm
new file mode 100644
index 000000000000..26f034593c67
--- /dev/null
+++ b/MdePkg/Library/BaseLib/X64/VmgExit.nasm
@@ -0,0 +1,32 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+; VmgExit.Asm
+;
+; Abstract:
+;
+; AsmVmgExit function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+ DEFAULT REL
+ SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; AsmVmgExit (
+; VOID
+; );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmVmgExit)
+ASM_PFX(AsmVmgExit):
+ rep vmmcall
+ ret
+