Reviewed-by: Feng Tian <feng.t...@intel.com> Thanks Feng
-----Original Message----- From: Laszlo Ersek [mailto:ler...@redhat.com] Sent: Wednesday, November 30, 2016 4:48 PM To: Fan, Jeff <jeff....@intel.com>; edk2-de...@ml01.01.org Cc: Kinney, Michael D <michael.d.kin...@intel.com>; Tian, Feng <feng.t...@intel.com>; Yao, Jiewen <jiewen....@intel.com> Subject: Re: [edk2] [PATCH] UefiCpuPkg/PiSmmCpuDxeSmm: Clear some semaphores on S3 boot path On 11/30/16 01:43, Fan, Jeff wrote: > Laszlo, > > Thanks your comments. I added my comments as below in [Jeff] Thanks for your answers. Acked-by: Laszlo Ersek <ler...@redhat.com> Tested-by: Laszlo Ersek <ler...@redhat.com> Cheers Laszlo > -----Original Message----- > From: Laszlo Ersek [mailto:ler...@redhat.com] > Sent: Wednesday, November 30, 2016 4:49 AM > To: Fan, Jeff; edk2-de...@ml01.01.org > Cc: Kinney, Michael D; Yao, Jiewen; Tian, Feng > Subject: Re: [edk2] [PATCH] UefiCpuPkg/PiSmmCpuDxeSmm: Clear some > semaphores on S3 boot path > > On 11/29/16 08:51, Jeff Fan wrote: >> Some semaphores are not cleared on S3 boot path. For example, >> mSmmMpSyncData->CpuData[CpuIndex].Present. It may still keeps the >> mSmmMpSyncData->value set at >> SMM runtime during S3 resume. It may causes BSP have the wrong >> judgement on SMM AP's present state. >> >> We have one related fix at e78a2a49ee6b0c0d7c6997c87ace31d7761cf636. >> But that is not completed. >> >> This fix is to clear Busy/Run/Present semaphores in InitializeMpSyncData(). >> >> Cc: Laszlo Ersek <ler...@redhat.com> >> Cc: Feng Tian <feng.t...@intel.com> >> Cc: Jiewen Yao <jiewen....@intel.com> >> Cc: Michael D Kinney <michael.d.kin...@intel.com> >> Contributed-under: TianoCore Contribution Agreement 1.0 >> Signed-off-by: Jeff Fan <jeff....@intel.com> >> --- >> UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c >> b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c >> index cfbf59e..a873b68 100644 >> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c >> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c >> @@ -1357,6 +1357,9 @@ InitializeMpSyncData ( >> (UINT32 *)((UINTN)mSmmCpuSemaphores.SemaphoreCpu.Run + >> mSemaphoreSize * CpuIndex); >> mSmmMpSyncData->CpuData[CpuIndex].Present = >> (BOOLEAN *)((UINTN)mSmmCpuSemaphores.SemaphoreCpu.Present + >> mSemaphoreSize * CpuIndex); >> + *(mSmmMpSyncData->CpuData[CpuIndex].Busy) = 0; >> + *(mSmmMpSyncData->CpuData[CpuIndex].Run) = 0; >> + *(mSmmMpSyncData->CpuData[CpuIndex].Present) = FALSE; >> } >> } >> } >> > > Even after this patch, the values pointed-to by the following fields of > SemaphoreGlobal are not cleared: PFLock, CodeAccessCheckLock, > MemoryMappedLock. Is that okay? > > The values pointed-to by the following fields of SemaphoreMsr are not cleared > either: Msr, AvailableCounter. Is that okay? > > [Jeff] We need to clear the data in > SMM_CPU_DATA_BLOCK/SMM_DISPATCHER_MP_SYNC_DATA and semaphores pointed by the > field in those 2 structures. However, the other spinlock located in > SemaphoreBlock needn't to be cleared. > > Can we imitate e78a2a49ee6b0c0d7c6997c87ace31d7761cf636 here; namely, > can we save "SemaphoreBlock" and "TotalSize" from > InitializeSmmCpuSemaphores() in global variables (in SMRAM), and then just do > another ZeroMem() here? That would cover the currently listed objects > (*Counter, *InsideSmm, *AllCpusInSync), and everything else too, in a > future-proof way. > > [Jeff] This issue is that ZeroMem only clear all the fields in structure and > needn't o clear the buffer pointed by these fields. > > In fact, I wonder if the ZeroMem() could be moved into > InitializeMpSyncData() from InitializeSmmCpuSemaphores(). > > [Jeff] If we cleared all semaphores(including Spinlock), we need to > re-initialize them again. I do not think there is some reasonable usage case > to let spinlock keep the garbage value. > > Of course, if some pointed-to objects must not be cleared, then the > ZeroMem() is not appropriate. > > [Jeff] Agree. > > Thanks! > Laszlo > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
