Re: [Patch 0/2] Separate semaphore container.

["Dong, Eric" <eric.dong@intel.com>]

Hi Stewards:
 
Since this is a bug fix, and the risk for this release is small. I plan to push this serial changes before edk2-stable201811 tag.

If you have any concern, please raise here. 

Thanks,
Eric

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Eric
> Dong
> Sent: Thursday, November 8, 2018 10:58 AM
> To: edk2-devel@lists.01.org
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Laszlo Ersek <lersek@redhat.com>
> Subject: [edk2] [Patch 0/2] Separate semaphore container.
> 
> In current implementation, core level semaphore use same container with
> package level semaphore. This design will let the core level semaphore not
> works as expected in below case:
> 1. Feature A has CPU_FEATURE_CORE_BEFORE dependence with Feature B.
> 2. Feature C has CPU_FEATURE_PACKAGE_AFTER dependence with Feature B.
> in this case an core level semaphore will be add between A and B, and an
> package level semaphore will be add between B and C.
> 
> For a CPU has one package, two cores and 4 threads. Execute like below:
> 
>   Thread 1          Thread 2    .....     Thread 4
> ReleaseSemaph(1,2)  -|
> WaitForSemaph(1(2)) -|<-----------------------These two are Core Semaph
>                   ReleaseSemaph(1,2) -|
>                   WaitForSemaph(2)   -| <---  Core Semaph
> 
> ReleaseSemaph (1,2,3,4) -|
> WaitForSemaph (1(4))    -| <----------------  Package Semaph
> 
>                                       ReleaseSemaph(3,4)
>                                       WaitForSemaph(4(2)) <- Core Semaph
> 
> In above case, for thread 4, when it executes a core semaphore, i will found
> WaitForSemaph(4(2)) is met because Thread 1 has execute a package
> semaphore and ReleaseSemaph(4) for it before. This is not an expect behavior.
> Thread 4 should wait for thread 3 to do this.
> 
> Fix this issue by separate the semaphore container for core level and package
> level.
> 
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> 
> Eric Dong (2):
>   UefiCpuPkg/RegisterCpuFeaturesLib: Separate semaphore container.
>   UefiCpuPkg/PiSmmCpuDxeSmm: Separate semaphore container.
> 
>  .../RegisterCpuFeaturesLib/CpuFeaturesInitialize.c  |  9 ++++++---
>  .../RegisterCpuFeaturesLib/RegisterCpuFeatures.h    |  7 ++++---
>  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c                   | 21 ++++++++++++++-------
>  3 files changed, 24 insertions(+), 13 deletions(-)
> 
> --
> 2.15.0.windows.1
> 
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