* [edk2-devel] [Patch V5 1/2] UefiCpuPkg/MpInitLib: Enable execute disable bit.
2023-11-20 4:18 [edk2-devel] [Patch V5 0/2] UefiCpuPkg/MpInitLib: Enable execute disable bit Yuanhao Xie
@ 2023-11-20 4:18 ` Yuanhao Xie
2023-11-20 4:18 ` [edk2-devel] [Patch V5 2/2] UefiCpuPkg/MpInitLib: Update the comments of _CPU_MP_DATA Yuanhao Xie
1 sibling, 0 replies; 3+ messages in thread
From: Yuanhao Xie @ 2023-11-20 4:18 UTC (permalink / raw)
To: devel
Cc: Yuanhao Xie, Laszlo Ersek, Eric Dong, Ray Ni, Rahul Kumar,
Gerd Hoffmann
From: Yuanhao Xie <yuanhao.xie@intel.com>
This patch synchronizes the No-Execute bit in the IA32_EFER
register for the APs before the RestoreVolatileRegisters operation.
The commit 964a4f0, titled "Eliminate the second INIT-SIPI-SIPI
sequence," replaces the second INIT-SIPI-SIPI sequence with the BSP
calling the SwitchApContext function to initiate a specialized start-up
signal, waking up APs in the DXE instead of using INIT-SIPI-SIPI.
Due to this change, the logic for "Enable execute disable bit" in
MpFuncs.nasm is no longer executed. However, to ensure the proper setup
of the page table, it is necessary to synchronize the IA32_EFER.NXE for
APs before executing RestoreVolatileRegisters .
Based on SDM:
If IA32_EFER.NXE is set to 1, it signifies execute-disable, meaning
instruction fetches are not allowed from the 4-KByte page controlled by
this entry. Conversely, if it is set to 0, it is reserved.
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Cc: Laszlo Ersek lersek@redhat.com
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
---
UefiCpuPkg/Library/MpInitLib/MpLib.c | 14 +++++++++++---
UefiCpuPkg/Library/MpInitLib/MpLib.h | 1 +
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index 9a6ec5db5c..f29e66a14f 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -910,9 +910,16 @@ DxeApEntryPoint (
CPU_MP_DATA *CpuMpData
)
{
- UINTN ProcessorNumber;
+ UINTN ProcessorNumber;
+ MSR_IA32_EFER_REGISTER EferMsr;
GetProcessorNumber (CpuMpData, &ProcessorNumber);
+ if (CpuMpData->EnableExecuteDisableForSwitchContext) {
+ EferMsr.Uint64 = AsmReadMsr64 (MSR_IA32_EFER);
+ EferMsr.Bits.NXE = 1;
+ AsmWriteMsr64 (MSR_IA32_EFER, EferMsr.Uint64);
+ }
+
RestoreVolatileRegisters (&CpuMpData->CpuData[0].VolatileRegisters, FALSE);
InterlockedIncrement ((UINT32 *)&CpuMpData->FinishedCount);
PlaceAPInMwaitLoopOrRunLoop (
@@ -2188,8 +2195,9 @@ MpInitLibInitialize (
if (MpHandOff->WaitLoopExecutionMode == sizeof (VOID *)) {
ASSERT (CpuMpData->ApLoopMode != ApInHltLoop);
- CpuMpData->FinishedCount = 0;
- CpuMpData->InitFlag = ApInitDone;
+ CpuMpData->FinishedCount = 0;
+ CpuMpData->InitFlag = ApInitDone;
+ CpuMpData->EnableExecuteDisableForSwitchContext = IsBspExecuteDisableEnabled ();
SaveCpuMpData (CpuMpData);
//
// In scenarios where both the PEI and DXE phases run in the same
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index 763db4963d..0afac7c78c 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -270,6 +270,7 @@ struct _CPU_MP_DATA {
UINT64 TotalTime;
EFI_EVENT WaitEvent;
UINTN **FailedCpuList;
+ BOOLEAN EnableExecuteDisableForSwitchContext
AP_INIT_STATE InitFlag;
BOOLEAN SwitchBspFlag;
--
2.39.1.windows.1
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^ permalink raw reply related [flat|nested] 3+ messages in thread* [edk2-devel] [Patch V5 2/2] UefiCpuPkg/MpInitLib: Update the comments of _CPU_MP_DATA.
2023-11-20 4:18 [edk2-devel] [Patch V5 0/2] UefiCpuPkg/MpInitLib: Enable execute disable bit Yuanhao Xie
2023-11-20 4:18 ` [edk2-devel] [Patch V5 1/2] " Yuanhao Xie
@ 2023-11-20 4:18 ` Yuanhao Xie
1 sibling, 0 replies; 3+ messages in thread
From: Yuanhao Xie @ 2023-11-20 4:18 UTC (permalink / raw)
To: devel; +Cc: xieyuanh, Eric Dong, Ray Ni, Rahul Kumar, Gerd Hoffmann
No functional changes in this patch.
Updated the comments of _CPU_MP_DATA to delcared that duplications in
CpuMpData are present to avoid to be direct accessed and comprehended
in assembly code. CpuMpData: Intended for use in C code while
ExchangeInfo are used in assembly code in this module.
Signed-off-by: Yuanhao Xie <yuanhao.xie@intel.com>
Cc: Laszlo Ersek lersek@redhat.com
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
---
UefiCpuPkg/Library/MpInitLib/MpLib.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index 0afac7c78c..242935816c 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -239,7 +239,11 @@ typedef struct {
#pragma pack()
//
-// CPU MP Data save in memory
+// CPU MP Data save in memory, and intended for use in C code.
+// There are some duplicated fields, such as XD status, between
+// CpuMpData and ExchangeInfo. These duplications in CpuMpData
+// are present to avoid to be direct accessed and comprehended
+// in assembly code.
//
struct _CPU_MP_DATA {
UINT64 CpuInfoInHob;
--
2.39.1.windows.1
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