* [edk2-devel] [PATCH v1] UefiCpuPkg/SmmCpu: Refine semaphore sync between BSP and AP
@ 2023-08-09 9:04 Wu, Jiaxin
0 siblings, 0 replies; 2+ messages in thread
From: Wu, Jiaxin @ 2023-08-09 9:04 UTC (permalink / raw)
To: devel; +Cc: Eric Dong, Ray Ni, Zeng Star, Rahul Kumar, Gerd Hoffmann
For SMM CPU semaphore sync, there is no need atomic semaphore
operation, just use the flag to indicate it has complete the
wait/release. Based on this, this patch is to refine 2 functions
(WaitForAllAPs & ReleaseAllAPs) and define 2 new functions
(WaitForBsp & ReleaseBsp) used for the semaphore sync between
BSP & AP.
Sync flow like below:
1. BSP to Release All APs ---> 1. AP to Wait BSP
ReleaseAllAPs () WaitForBsp
2. BSP to Wait All APs <--- 2. AP to Release BSP
WaitForAllAPs () ReleaseBsp
With this change, SMM CPU semaphore sync for SMI exit performance
will be significant improved.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zeng Star <star.zeng@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
---
UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 68 ++++++++++++++++++++++++++---------
1 file changed, 51 insertions(+), 17 deletions(-)
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index 25d058c5b9..0bf460e81c 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -120,11 +120,11 @@ LockdownSemaphore (
return Value;
}
/**
- Wait all APs to performs an atomic compare exchange operation to release semaphore.
+ Used for BSP to wait all APs.
@param NumberOfAPs AP number
**/
VOID
@@ -133,18 +133,19 @@ WaitForAllAPs (
)
{
UINTN BspIndex;
BspIndex = mSmmMpSyncData->BspIndex;
- while (NumberOfAPs-- > 0) {
- WaitForSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ while (NumberOfAPs != *mSmmMpSyncData->CpuData[BspIndex].Run) {
+ CpuPause ();
}
+
+ *mSmmMpSyncData->CpuData[BspIndex].Run = 0;
}
/**
- Performs an atomic compare exchange operation to release semaphore
- for each AP.
+ Used for BSP to release all APs.
**/
VOID
ReleaseAllAPs (
VOID
@@ -152,15 +153,48 @@ ReleaseAllAPs (
{
UINTN Index;
for (Index = 0; Index < mMaxNumberOfCpus; Index++) {
if (IsPresentAp (Index)) {
- ReleaseSemaphore (mSmmMpSyncData->CpuData[Index].Run);
+ ASSERT (*mSmmMpSyncData->CpuData[Index].Run == 0);
+ *mSmmMpSyncData->CpuData[Index].Run = 1;
}
}
}
+/**
+ Used for Ap to wait BSP.
+
+ @param ApSem IN: 32-bit unsigned integer
+ OUT: original integer 0
+**/
+VOID
+WaitForBsp (
+ IN OUT volatile UINT32 *ApSem
+ )
+{
+ while (*ApSem == 0) {
+ CpuPause ();
+ }
+
+ *ApSem = 0;
+}
+
+/**
+ Used for Ap to release BSP.
+
+ @param BspSem IN: 32-bit unsigned integer
+ OUT: original integer + 1
+**/
+VOID
+ReleaseBsp (
+ IN OUT volatile UINT32 *BspSem
+ )
+{
+ InterlockedIncrement (BspSem);
+}
+
/**
Check whether the index of CPU perform the package level register
programming during System Management Mode initialization.
The index of Processor specified by mPackageFirstThreadIndex[PackageIndex]
@@ -898,50 +932,50 @@ APHandler (
if ((SyncMode == SmmCpuSyncModeTradition) || SmmCpuFeaturesNeedConfigureMtrrs ()) {
//
// Notify BSP of arrival at this point
//
- ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
}
if (SmmCpuFeaturesNeedConfigureMtrrs ()) {
//
// Wait for the signal from BSP to backup MTRRs
//
- WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
+ WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
//
// Backup OS MTRRs
//
MtrrGetAllMtrrs (&Mtrrs);
//
// Signal BSP the completion of this AP
//
- ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
//
// Wait for BSP's signal to program MTRRs
//
- WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
+ WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
//
// Replace OS MTRRs with SMI MTRRs
//
ReplaceOSMtrrs (CpuIndex);
//
// Signal BSP the completion of this AP
//
- ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
}
while (TRUE) {
//
// Wait for something to happen
//
- WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
+ WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
//
// Check if BSP wants to exit SMM
//
if (!(*mSmmMpSyncData->InsideSmm)) {
@@ -977,16 +1011,16 @@ APHandler (
if (SmmCpuFeaturesNeedConfigureMtrrs ()) {
//
// Notify BSP the readiness of this AP to program MTRRs
//
- ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
//
// Wait for the signal from BSP to program MTRRs
//
- WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
+ WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
//
// Restore OS MTRRs
//
SmmCpuFeaturesReenableSmrr ();
@@ -994,26 +1028,26 @@ APHandler (
}
//
// Notify BSP the readiness of this AP to Reset states/semaphore for this processor
//
- ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
//
// Wait for the signal from BSP to Reset states/semaphore for this processor
//
- WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
+ WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
//
// Reset states/semaphore for this processor
//
*(mSmmMpSyncData->CpuData[CpuIndex].Present) = FALSE;
//
// Notify BSP the readiness of this AP to exit SMM
//
- ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
+ ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
}
/**
Checks whether the input token is the current used token.
--
2.16.2.windows.1
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [edk2-devel] [PATCH v1] UefiCpuPkg/SmmCpu: Refine semaphore sync between BSP and AP
[not found] <1779ABA9805F8956.9264@groups.io>
@ 2023-08-16 0:26 ` Wu, Jiaxin
0 siblings, 0 replies; 2+ messages in thread
From: Wu, Jiaxin @ 2023-08-16 0:26 UTC (permalink / raw)
To: devel@edk2.groups.io, Wu, Jiaxin, Kinney, Michael D
Cc: Dong, Eric, Ni, Ray, Zeng, Star, Kumar, Rahul R, Gerd Hoffmann
+Mike for this review.
> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Wu,
> Jiaxin
> Sent: Wednesday, August 9, 2023 5:04 PM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Zeng, Star
> <star.zeng@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>; Gerd
> Hoffmann <kraxel@redhat.com>
> Subject: [edk2-devel] [PATCH v1] UefiCpuPkg/SmmCpu: Refine semaphore
> sync between BSP and AP
>
> For SMM CPU semaphore sync, there is no need atomic semaphore
> operation, just use the flag to indicate it has complete the
> wait/release. Based on this, this patch is to refine 2 functions
> (WaitForAllAPs & ReleaseAllAPs) and define 2 new functions
> (WaitForBsp & ReleaseBsp) used for the semaphore sync between
> BSP & AP.
>
> Sync flow like below:
> 1. BSP to Release All APs ---> 1. AP to Wait BSP
> ReleaseAllAPs () WaitForBsp
> 2. BSP to Wait All APs <--- 2. AP to Release BSP
> WaitForAllAPs () ReleaseBsp
>
> With this change, SMM CPU semaphore sync for SMI exit performance
> will be significant improved.
>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Zeng Star <star.zeng@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
> ---
> UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 68
> ++++++++++++++++++++++++++---------
> 1 file changed, 51 insertions(+), 17 deletions(-)
>
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> index 25d058c5b9..0bf460e81c 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> @@ -120,11 +120,11 @@ LockdownSemaphore (
>
> return Value;
> }
>
> /**
> - Wait all APs to performs an atomic compare exchange operation to release
> semaphore.
> + Used for BSP to wait all APs.
>
> @param NumberOfAPs AP number
>
> **/
> VOID
> @@ -133,18 +133,19 @@ WaitForAllAPs (
> )
> {
> UINTN BspIndex;
>
> BspIndex = mSmmMpSyncData->BspIndex;
> - while (NumberOfAPs-- > 0) {
> - WaitForSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + while (NumberOfAPs != *mSmmMpSyncData->CpuData[BspIndex].Run) {
> + CpuPause ();
> }
> +
> + *mSmmMpSyncData->CpuData[BspIndex].Run = 0;
> }
>
> /**
> - Performs an atomic compare exchange operation to release semaphore
> - for each AP.
> + Used for BSP to release all APs.
>
> **/
> VOID
> ReleaseAllAPs (
> VOID
> @@ -152,15 +153,48 @@ ReleaseAllAPs (
> {
> UINTN Index;
>
> for (Index = 0; Index < mMaxNumberOfCpus; Index++) {
> if (IsPresentAp (Index)) {
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[Index].Run);
> + ASSERT (*mSmmMpSyncData->CpuData[Index].Run == 0);
> + *mSmmMpSyncData->CpuData[Index].Run = 1;
> }
> }
> }
>
> +/**
> + Used for Ap to wait BSP.
> +
> + @param ApSem IN: 32-bit unsigned integer
> + OUT: original integer 0
> +**/
> +VOID
> +WaitForBsp (
> + IN OUT volatile UINT32 *ApSem
> + )
> +{
> + while (*ApSem == 0) {
> + CpuPause ();
> + }
> +
> + *ApSem = 0;
> +}
> +
> +/**
> + Used for Ap to release BSP.
> +
> + @param BspSem IN: 32-bit unsigned integer
> + OUT: original integer + 1
> +**/
> +VOID
> +ReleaseBsp (
> + IN OUT volatile UINT32 *BspSem
> + )
> +{
> + InterlockedIncrement (BspSem);
> +}
> +
> /**
> Check whether the index of CPU perform the package level register
> programming during System Management Mode initialization.
>
> The index of Processor specified by
> mPackageFirstThreadIndex[PackageIndex]
> @@ -898,50 +932,50 @@ APHandler (
>
> if ((SyncMode == SmmCpuSyncModeTradition) ||
> SmmCpuFeaturesNeedConfigureMtrrs ()) {
> //
> // Notify BSP of arrival at this point
> //
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
> }
>
> if (SmmCpuFeaturesNeedConfigureMtrrs ()) {
> //
> // Wait for the signal from BSP to backup MTRRs
> //
> - WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
> + WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
>
> //
> // Backup OS MTRRs
> //
> MtrrGetAllMtrrs (&Mtrrs);
>
> //
> // Signal BSP the completion of this AP
> //
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
>
> //
> // Wait for BSP's signal to program MTRRs
> //
> - WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
> + WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
>
> //
> // Replace OS MTRRs with SMI MTRRs
> //
> ReplaceOSMtrrs (CpuIndex);
>
> //
> // Signal BSP the completion of this AP
> //
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
> }
>
> while (TRUE) {
> //
> // Wait for something to happen
> //
> - WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
> + WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
>
> //
> // Check if BSP wants to exit SMM
> //
> if (!(*mSmmMpSyncData->InsideSmm)) {
> @@ -977,16 +1011,16 @@ APHandler (
>
> if (SmmCpuFeaturesNeedConfigureMtrrs ()) {
> //
> // Notify BSP the readiness of this AP to program MTRRs
> //
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
>
> //
> // Wait for the signal from BSP to program MTRRs
> //
> - WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
> + WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
>
> //
> // Restore OS MTRRs
> //
> SmmCpuFeaturesReenableSmrr ();
> @@ -994,26 +1028,26 @@ APHandler (
> }
>
> //
> // Notify BSP the readiness of this AP to Reset states/semaphore for this
> processor
> //
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
>
> //
> // Wait for the signal from BSP to Reset states/semaphore for this processor
> //
> - WaitForSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
> + WaitForBsp (mSmmMpSyncData->CpuData[CpuIndex].Run);
>
> //
> // Reset states/semaphore for this processor
> //
> *(mSmmMpSyncData->CpuData[CpuIndex].Present) = FALSE;
>
> //
> // Notify BSP the readiness of this AP to exit SMM
> //
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> + ReleaseBsp (mSmmMpSyncData->CpuData[BspIndex].Run);
> }
>
> /**
> Checks whether the input token is the current used token.
>
> --
> 2.16.2.windows.1
>
>
>
>
>
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2023-08-09 9:04 [edk2-devel] [PATCH v1] UefiCpuPkg/SmmCpu: Refine semaphore sync between BSP and AP Wu, Jiaxin
[not found] <1779ABA9805F8956.9264@groups.io>
2023-08-16 0:26 ` Wu, Jiaxin
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