Re: [edk2-devel] [PATCH v3 1/2] UefiCpuPkg/MpInitLib: Restore IDT context for APs.

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

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Wednesday, April 29, 2020 6:59 PM
> To: devel@edk2.groups.io; Dong, Eric <eric.dong@intel.com>
> Cc: Ni, Ray <ray.ni@intel.com>; Kumar, Chandana C
> <chandana.c.kumar@intel.com>
> Subject: Re: [edk2-devel] [PATCH v3 1/2] UefiCpuPkg/MpInitLib: Restore IDT
> context for APs.
> 
> Hi Eric,
> 
> (1) on the email address list of this patch set, there is a strange item:
> 
> 00000000  16 64 65 76 65 6c 40 65  64 6b 32 2e 67 72 6f 75  |.devel@edk2.grou|
> 00000010  70 73 2e 69 6f                                    |ps.io|
> 
> The first character is U+0016, which seems to stand for SYNCHRONOUS IDLE
> <https://en.wikipedia.org/wiki/Synchronous_Idle>. I think it must have been
> a typo.
> 

I copied the mail address from outlook, maybe some invisible characters caused this error.
 
> (The set was otherwise posted correctly to the list -- the correct list address is
> present, too.)
> 
> Pointing this out just for future postings.
> 
> On 04/24/20 10:47, Dong, Eric wrote:
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2683
> >
> > This patch fixes an assertion because AP can't find the CpuMpData.
> > When AP is waken up through Init-Sipi-Sipi, AP's IDT should be
> > restored to pre-allocated buffer so AP can get the CpuMpData through
> > the IDT base address.
> > Current code already has logic to handle this when CpuMpData->
> > InitFlag is ApInitConfig but misses the logic when CpuMpData->InitFlag
> > is ApInitReconfig.
> > This patch fixes this gap.
> >
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Cc: Chandana Kumar <chandana.c.kumar@intel.com>
> > Signed-off-by: Eric Dong <eric.dong@intel.com>
> > ---
> > V3:
> >   Remove invalid save volatile registers process. Refine restore
> >   volatile registers process.
> >
> > V2:
> >   Enhance code to remove CpuMpData->ApLoopMode == ApInHltLoop
> check.
> >
> >  UefiCpuPkg/Library/MpInitLib/MpLib.c | 34
> > +++++++++++++++++++---------
> >  1 file changed, 23 insertions(+), 11 deletions(-)
> >
> > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > index 64a4c3546e..7fd757b428 100644
> > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > @@ -686,18 +686,31 @@ ApWakeupFunction (
> >          WAKEUP_AP_SIGNAL,
> >          0
> >          );
> > -      if (CpuMpData->ApLoopMode == ApInHltLoop) {
> > -        //
> > -        // Restore AP's volatile registers saved
> > -        //
> > -        RestoreVolatileRegisters (&CpuMpData-
> >CpuData[ProcessorNumber].VolatileRegisters, TRUE);
> > -      } else {
> > +
> > +      if (CpuMpData->InitFlag == ApInitReconfig) {
> >          //
> > -        // The CPU driver might not flush TLB for APs on spot after updating
> > -        // page attributes. AP in mwait loop mode needs to take care of it
> when
> > -        // woken up.
> > +        // ApInitReconfig happens when:
> > +        // 1. AP is re-enabled after it's disabled, in either PEI or DXE phase.
> > +        // 2. AP is initialized in DXE phase.
> 
> (2) git-am complains that the line above has a trailing space character. Please
> remove it before you push the set.

Got it. Will remove it when merge the code.

> 
> > +        // In either case, use the volatile registers value derived from BSP.
> > +        // NOTE: IDTR.BASE stored in CpuMpData-
> >CpuData[0].VolatileRegisters points to a
> > +        //   different IDT shared by all APs.
> >          //
> > -        CpuFlushTlb ();
> > +        RestoreVolatileRegisters (&CpuMpData-
> >CpuData[0].VolatileRegisters, FALSE);
> > +      }  else {
> > +        if (CpuMpData->ApLoopMode == ApInHltLoop) {
> > +          //
> > +          // Restore AP's volatile registers saved before AP is halted
> > +          //
> > +          RestoreVolatileRegisters (&CpuMpData-
> >CpuData[ProcessorNumber].VolatileRegisters, TRUE);
> > +        } else {
> > +          //
> > +          // The CPU driver might not flush TLB for APs on spot after updating
> > +          // page attributes. AP in mwait loop mode needs to take care of it
> when
> > +          // woken up.
> > +          //
> > +          CpuFlushTlb ();
> > +        }
> >        }
> >
> >        if (GetApState (&CpuMpData->CpuData[ProcessorNumber]) ==
> > CpuStateReady) { @@ -1780,7 +1793,6 @@ MpInitLibInitialize (
> >        InitializeSpinLock(&CpuMpData->CpuData[Index].ApLock);
> >        CpuMpData->CpuData[Index].CpuHealthy =
> (CpuInfoInHob[Index].Health == 0)? TRUE:FALSE;
> >        CpuMpData->CpuData[Index].ApFunction = 0;
> > -      CopyMem (&CpuMpData->CpuData[Index].VolatileRegisters,
> &VolatileRegisters, sizeof (CPU_VOLATILE_REGISTERS));
> >      }
> >    }
> >
> >
> 
> For the full series:
> 
> Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
> 
> (For the testing, I used OVMF, with/without SMM, and normal boot and S3.
> With SMM, I also tested CPU hotplug. OVMF doesn't support "microcode
> patching", so maybe it didn't make sense to perform these regression-tests.
> But, "these patches should be harmless regarding <whatever>", are famous
> last words... So I rather wanted to regression-test them, under my use case.)

Thanks for your test! Very appreciate your supports.

> 
> Thanks,
> Laszlo