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UefiCpuPkg/CpuExceptionHandler: Add base support for the #VC exception 

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

Add base support to handle #VC exceptions. Update the common exception
handlers to invoke the VmgExitHandleVc () function of the VmgExitLib
library when a #VC is encountered. A non-zero return code will propagate
to the targeted exception handler.

Under SEV-ES, a DR7 read or write intercept generates a #VC exception.
To avoid exception recursion, a #VC exception will not try to read and
push the actual debug registers into the EFI_SYSTEM_CONTEXT_X64 struct
and instead push zeroes. The #VC exception handler does not make use of
the debug registers from the saved context and the exception processing
exit code does not attempt to restore the debug register values.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Tom Lendacky 2020-08-12 15:21:36 -05:00 committed by mergify[bot]
parent 3a4a6ead32
commit 5277540e37
10 changed files with 86 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
UefiCpuPkg/Library/CpuExceptionHandlerLib/CpuExceptionCommon.c
View File

@ -14,7 +14,7 @@
//
// 1 means an error code will be pushed, otherwise 0
//
CONST UINT32 mErrorCodeFlag = 0x00227d00;
CONST UINT32 mErrorCodeFlag = 0x20227d00;
//
// Define the maximum message length
@ -45,6 +45,14 @@ CONST CHAR8 *mExceptionNameStr[] = {
"#XM - SIMD floating-point",
"#VE - Virtualization",
"#CP - Control Protection"
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"Reserved",
"#VC - VMM Communication",
};
#define EXCEPTION_KNOWN_NAME_NUM (sizeof (mExceptionNameStr) / sizeof (CHAR8 *))

1
UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeCpuExceptionHandlerLib.inf
View File

@ -57,3 +57,4 @@
PeCoffGetEntryPointLib
MemoryAllocationLib
DebugLib
VmgExitLib

1
UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuExceptionHandlerLib.inf
View File

@ -52,6 +52,7 @@
HobLib
MemoryAllocationLib
SynchronizationLib
VmgExitLib
[Pcd]
gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard # CONSUMES

20
UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiDxeSmmCpuException.c
View File

@ -6,8 +6,9 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "CpuExceptionCommon.h"
#include <Library/DebugLib.h>
#include <Library/VmgExitLib.h>
#include "CpuExceptionCommon.h"
/**
Internal worker function for common exception handler.
@ -27,6 +28,23 @@ CommonExceptionHandlerWorker (
RESERVED_VECTORS_DATA *ReservedVectors;
EFI_CPU_INTERRUPT_HANDLER *ExternalInterruptHandler;
if (ExceptionType == VC_EXCEPTION) {
EFI_STATUS Status;
//
// #VC needs to be handled immediately upon enabling exception handling
// and therefore can't use the RegisterCpuInterruptHandler() interface.
//
// Handle the #VC:
// On EFI_SUCCESS - Exception has been handled, return
// On other - ExceptionType contains (possibly new) exception
// value
//
Status = VmgExitHandleVc (&ExceptionType, SystemContext);
if (!EFI_ERROR (Status)) {
return;
}
}
ExceptionHandlerContext = (EXCEPTION_HANDLER_CONTEXT *) (UINTN) (SystemContext.SystemContextIa32);
ReservedVectors = ExceptionHandlerData->ReservedVectors;
ExternalInterruptHandler = ExceptionHandlerData->ExternalInterruptHandler;

19
UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuException.c
View File

@ -7,6 +7,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <PiPei.h>
#include <Library/VmgExitLib.h>
#include "CpuExceptionCommon.h"
CONST UINTN mDoFarReturnFlag = 0;
@ -24,6 +25,24 @@ CommonExceptionHandler (
IN EFI_SYSTEM_CONTEXT SystemContext
)
{
if (ExceptionType == VC_EXCEPTION) {
EFI_STATUS Status;
//
// #VC needs to be handled immediately upon enabling exception handling
// and therefore can't use the RegisterCpuInterruptHandler() interface
// (which isn't supported under Sec and Pei anyway).
//
// Handle the #VC:
// On EFI_SUCCESS - Exception has been handled, return
// On other - ExceptionType contains (possibly new) exception
// value
//
Status = VmgExitHandleVc (&ExceptionType, SystemContext);
if (!EFI_ERROR (Status)) {
return;
}
}
//
// Initialize the serial port before dumping.
//

1
UefiCpuPkg/Library/CpuExceptionHandlerLib/SecPeiCpuExceptionHandlerLib.inf
View File

@ -48,3 +48,4 @@
PrintLib
LocalApicLib
PeCoffGetEntryPointLib
VmgExitLib

1
UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmCpuExceptionHandlerLib.inf
View File

@ -51,4 +51,5 @@
LocalApicLib
PeCoffGetEntryPointLib
DebugLib
VmgExitLib

17
UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.nasm
View File

@ -18,6 +18,8 @@
; CommonExceptionHandler()
;
%define VC_EXCEPTION 29
extern ASM_PFX(mErrorCodeFlag) ; Error code flags for exceptions
extern ASM_PFX(mDoFarReturnFlag) ; Do far return flag
extern ASM_PFX(CommonExceptionHandler)
@ -224,6 +226,9 @@ HasErrorCode:
push rax
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
cmp qword [rbp + 8], VC_EXCEPTION
je VcDebugRegs ; For SEV-ES (#VC) Debug registers ignored
mov rax, dr7
push rax
mov rax, dr6
@ -236,7 +241,19 @@ HasErrorCode:
push rax
mov rax, dr0
push rax
jmp DrFinish
VcDebugRegs:
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7 are skipped for #VC to avoid exception recursion
xor rax, rax
push rax
push rax
push rax
push rax
push rax
push rax
DrFinish:
;; FX_SAVE_STATE_X64 FxSaveState;
sub rsp, 512
mov rdi, rsp

17
UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/Xcode5ExceptionHandlerAsm.nasm
View File

@ -18,6 +18,8 @@
; CommonExceptionHandler()
;
%define VC_EXCEPTION 29
extern ASM_PFX(mErrorCodeFlag) ; Error code flags for exceptions
extern ASM_PFX(mDoFarReturnFlag) ; Do far return flag
extern ASM_PFX(CommonExceptionHandler)
@ -225,6 +227,9 @@ HasErrorCode:
push rax
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
cmp qword [rbp + 8], VC_EXCEPTION
je VcDebugRegs ; For SEV-ES (#VC) Debug registers ignored
mov rax, dr7
push rax
mov rax, dr6
@ -237,7 +242,19 @@ HasErrorCode:
push rax
mov rax, dr0
push rax
jmp DrFinish
VcDebugRegs:
;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7 are skipped for #VC to avoid exception recursion
xor rax, rax
push rax
push rax
push rax
push rax
push rax
push rax
DrFinish:
;; FX_SAVE_STATE_X64 FxSaveState;
sub rsp, 512
mov rdi, rsp

1
UefiCpuPkg/Library/CpuExceptionHandlerLib/Xcode5SecPeiCpuExceptionHandlerLib.inf
View File

@ -53,3 +53,4 @@
PrintLib
LocalApicLib
PeCoffGetEntryPointLib
VmgExitLib