UefiCpuPkg: Fix potential spinLock issue in SmmStartupThisAp

Due to needs a tackling the deficiency of the AP API, it's necessary to
ensure that in non-blocking mode previous AP executed command is
finished before starting new one.

To remedy above:
  1) execute AcquireSpinLock instead AcquireSpinLockOrFail - this will
     ensure time "window" to eliminate potential race condition between
     BSP and AP spinLock release in non-blocking mode.
     This also will eliminate possibility to start executing new AP
     function before last is finished.
  2) remove returns EFI_STATUS - EFI_NOT_READY - in new scenario returned
     status is not necessary to caller.

Signed-off-by: Damian Nikodem <damian.nikodem@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Krzysztof Rusocki <krzysztof.rusocki@intel.com>

1 files changed, 2 insertions, 7 deletions

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
index d8d2b6f444..0685637c2b 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
@@ -1235,14 +1235,9 @@ InternalSmmStartupThisAp (
     return EFI_INVALID_PARAMETER;

   }

 

-  if (Token == NULL) {

-    AcquireSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);

-  } else {

-    if (!AcquireSpinLockOrFail (mSmmMpSyncData->CpuData[CpuIndex].Busy)) {

-      DEBUG((DEBUG_ERROR, "Can't acquire mSmmMpSyncData->CpuData[%d].Busy\n", CpuIndex));

-      return EFI_NOT_READY;

-    }

+  AcquireSpinLock (mSmmMpSyncData->CpuData[CpuIndex].Busy);

 

+  if (Token != NULL) {

     *Token = (MM_COMPLETION) CreateToken ();

   }