Reviewed-by: Ray Ni <ray...@intel.com>
Thanks,
Ray
> -----Original Message-----
> From: Wu, Jiaxin <jiaxin...@intel.com>
> Sent: Friday, December 15, 2023 5:55 PM
> To: devel@edk2.groups.io
> Cc: Laszlo Ersek <ler...@redhat.com>; Dong, Eric <eric.d...@intel.com>; Ni,
> Ray <ray...@intel.com>; Zeng, Star <star.z...@intel.com>; Kumar, Rahul R
> <rahul.r.ku...@intel.com>; Gerd Hoffmann <kra...@redhat.com>
> Subject: [PATCH v4 1/8] UefiCpuPkg/PiSmmCpuDxeSmm: Optimize
> Semaphore Sync between BSP and AP
>
> This patch is to define 3 new functions (WaitForBsp & ReleaseBsp &
> ReleaseOneAp) used for the semaphore sync between BSP & AP. With the
> change, BSP and AP Sync flow will be easy understand as below:
> BSP: ReleaseAllAPs or ReleaseOneAp --> AP: WaitForBsp
> BSP: WaitForAllAPs <-- AP: ReleaseBsp
>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Ray Ni <ray...@intel.com>
> Cc: Zeng Star <star.z...@intel.com>
> Cc: Rahul Kumar <rahul1.ku...@intel.com>
> Cc: Gerd Hoffmann <kra...@redhat.com>
> Signed-off-by: Jiaxin Wu <jiaxin...@intel.com>
> Reviewed-by: Laszlo Ersek <ler...@redhat.com>
> ---
> UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 72
> ++++++++++++++++++++++++++++-------
> 1 file changed, 58 insertions(+), 14 deletions(-)
>
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> index b279f5dfcc..54542262a2 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> @@ -120,10 +120,11 @@ LockdownSemaphore (
>
> return Value;
> }
>
> /**
> + Used for BSP to wait all APs.
> Wait all APs to performs an atomic compare exchange operation to
> release semaphore.
>
> @param NumberOfAPs AP number
>
> **/
> @@ -139,10 +140,11 @@ WaitForAllAPs (
> WaitForSemaphore (mSmmMpSyncData->CpuData[BspIndex].Run);
> }
> }
>
> /**
> + Used for BSP to release all APs.
> Performs an atomic compare exchange operation to release semaphore
> for each AP.
>
> **/
> VOID
> @@ -157,10 +159,52 @@ ReleaseAllAPs (
> ReleaseSemaphore (mSmmMpSyncData->CpuData[Index].Run);
> }
> }
> }
>
> +/**
> + Used for BSP to release one AP.
> +
> + @param ApSem IN: 32-bit unsigned integer
> + OUT: original integer + 1
> +**/
> +VOID
> +ReleaseOneAp (
> + IN OUT volatile UINT32 *ApSem
> + )
> +{
> + ReleaseSemaphore (ApSem);
> +}
> +
> +/**
> + Used for AP to wait BSP.
> +
> + @param ApSem IN: 32-bit unsigned integer
> + OUT: original integer - 1
> +**/
> +VOID
> +WaitForBsp (
> + IN OUT volatile UINT32 *ApSem
> + )
> +{
> + WaitForSemaphore (ApSem);
> +}
> +
> +/**
> + Used for AP to release BSP.
> +
> + @param BspSem IN: 32-bit unsigned integer
> + OUT: original integer + 1
> +**/
> +VOID
> +ReleaseBsp (
> + IN OUT volatile UINT32 *BspSem
> + )
> +{
> + ReleaseSemaphore (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]
> @@ -632,11 +676,11 @@ BSPHandler (
> // Signal all APs it's time for backup MTRRs
> //
> ReleaseAllAPs ();
>
> //
> - // WaitForSemaphore() may wait for ever if an AP happens to enter
> SMM at
> + // WaitForAllAPs() may wait for ever if an AP happens to enter SMM
> at
> // exactly this point. Please make sure PcdCpuSmmMaxSyncLoops
> has been set
> // to a large enough value to avoid this situation.
> // Note: For HT capable CPUs, threads within a core share the same
> set of MTRRs.
> // We do the backup first and then set MTRR to avoid race condition
> for threads
> // in the same core.
> @@ -652,11 +696,11 @@ BSPHandler (
> // Let all processors program SMM MTRRs together
> //
> ReleaseAllAPs ();
>
> //
> - // WaitForSemaphore() may wait for ever if an AP happens to enter
> SMM at
> + // WaitForAllAPs() may wait for ever if an AP happens to enter SMM
> at
> // exactly this point. Please make sure PcdCpuSmmMaxSyncLoops
> has been set
> // to a large enough value to avoid this situation.
> //
> ReplaceOSMtrrs (CpuIndex);
>
> @@ -898,50 +942,50 @@ 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 +1021,16 @@ 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 +1038,26 @@ 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.
>
> @@ -1277,11 +1321,11 @@ InternalSmmStartupThisAp (
> mSmmMpSyncData->CpuData[CpuIndex].Status = CpuStatus;
> if (mSmmMpSyncData->CpuData[CpuIndex].Status != NULL) {
> *mSmmMpSyncData->CpuData[CpuIndex].Status = EFI_NOT_READY;
> }
>
> - ReleaseSemaphore (mSmmMpSyncData->CpuData[CpuIndex].Run);
> + ReleaseOneAp (mSmmMpSyncData->CpuData[CpuIndex].Run);
>
> if (Token == NULL) {
> AcquireSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);
> ReleaseSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);
> }
> --
> 2.16.2.windows.1
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