Re: [edk2-devel] [Patch v2 0/6] Add "test then write" mechanism.

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

Hi liming,

This is a bug fix. It is required by 201908 stable tag.

Thanks,
Eric

> -----Original Message-----
> From: Gao, Liming
> Sent: Wednesday, August 14, 2019 3:27 PM
> To: devel@edk2.groups.io; Dong, Eric <eric.dong@intel.com>;
> lersek@redhat.com
> Cc: Ni, Ray <ray.ni@intel.com>; leif.lindholm@linaro.org; afish@apple.com;
> Cetola, Stephano <stephano.cetola@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>
> Subject: RE: [edk2-devel] [Patch v2 0/6] Add "test then write" mechanism.
> 
> Eric:
>   Is this a bug fix or new feature? Dose it catch to this 201908 stable tag?
> 
> Thanks
> Liming
> >-----Original Message-----
> >From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> >Dong, Eric
> >Sent: Tuesday, August 13, 2019 10:29 AM
> >To: devel@edk2.groups.io; lersek@redhat.com
> >Cc: Ni, Ray <ray.ni@intel.com>
> >Subject: Re: [edk2-devel] [Patch v2 0/6] Add "test then write" mechanism.
> >
> >Hi Laszlo,
> >
> >Yes, I already checked IA32 build.
> >
> >As Ray is leaving these days, can you help to review this serial?
> >
> >Thanks,
> >Eric
> >
> >> -----Original Message-----
> >> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> >> Laszlo Ersek
> >> Sent: Monday, August 12, 2019 10:15 PM
> >> To: Dong, Eric <eric.dong@intel.com>; devel@edk2.groups.io
> >> Cc: Ni, Ray <ray.ni@intel.com>
> >> Subject: Re: [edk2-devel] [Patch v2 0/6] Add "test then write" mechanism.
> >>
> >> On 08/12/19 12:31, Eric Dong wrote:
> >> > V2 changes:
> >> > 1. Split CR read/write action in to one discrete patch 2. Keep the
> >> > old logic which continue the process if error found.
> >> >
> >> > Below code is current implementation:
> >> >   if (MsrRegister[ProcessorNumber].Bits.Lock == 0) {
> >> >     CPU_REGISTER_TABLE_WRITE_FIELD (
> >> >       ProcessorNumber,
> >> >       Msr,
> >> >       MSR_IA32_FEATURE_CONTROL,
> >> >       MSR_IA32_FEATURE_CONTROL_REGISTER,
> >> >       Bits.Lock,
> >> >       1
> >> >     );
> >> >   }
> >> >
> >> > With below steps, the Bits.Lock bit will lose its value:
> >> > 1. Trig normal boot, the Bits.Lock is 0. 1 will be added
> >> >    into the register table and then will set to the MSR.
> >> > 2. Trig warm reboot, MSR value preserves. After normal boot phase,
> >> >    the Bits.Lock is 1, so it will not be added into the register
> >> >    table during the warm reboot phase.
> >> > 3. Trig S3 then resume, the Bits.Lock change to 0 and Bits.Lock is
> >> >    not added in register table during normal boot phase. so it's
> >> >    still 0 after resume.
> >> > This is not an expect behavior. The expect result is the value
> >> > should always 1 after booting or resuming from S3.
> >> >
> >> > The root cause for this issue is
> >> > 1. driver bases on current value to insert the "set value action" to
> >> >    the register table.
> >> > 2. Some MSRs may reserve their value during warm reboot. So the
> insert
> >> >    action may be skip after warm reboot.
> >> >
> >> > The solution for this issue is:
> >> > 1. Always add "Test then Set" action for above referred MSRs.
> >> > 2. Detect current value before set new value. Only set new value when
> >> >    current value not same as new value.
> >> >
> >> > Cc: Ray Ni <ray.ni@intel.com>
> >> > Cc: Laszlo Ersek <lersek@redhat.com>
> >> >
> >> > Eric Dong (6):
> >> >   UefiCpuPkg/RegisterCpuFeaturesLib: Add "Test Then Write" Macros.
> >> >   UefiCpuPkg/PiSmmCpuDxeSmm: Combine CR read/write action in one
> >> >     function.
> >> >   UefiCpuPkg/PiSmmCpuDxeSmm: Supports test then write new value
> >logic.
> >> >   UefiCpuPkg/RegisterCpuFeaturesLib: Combine CR read/write action
> >> > in
> >> one
> >> >     function.
> >> >   UefiCpuPkg/RegisterCpuFeaturesLib: Supports test then write new
> value
> >> >     logic.
> >> >   UefiCpuPkg/CpuCommonFeaturesLib: Use new macros.
> >> >
> >> >  UefiCpuPkg/Include/AcpiCpuData.h              |   1 +
> >> >  .../Include/Library/RegisterCpuFeaturesLib.h  |  77 +++++++++-
> >> > .../CpuCommonFeaturesLib/CpuCommonFeatures.h  |  15 --
> >> >  .../CpuCommonFeaturesLib.c                    |   8 +-
> >> >  .../CpuCommonFeaturesLib/FeatureControl.c     | 141 ++++++------------
> >> >  .../CpuCommonFeaturesLib/MachineCheck.c       |  23 ++-
> >> >  .../CpuFeaturesInitialize.c                   | 141 ++++++++++++------
> >> >  .../RegisterCpuFeaturesLib.c                  |  14 +-
> >> >  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c             | 135 +++++++++++----
> --
> >> >  9 files changed, 323 insertions(+), 232 deletions(-)
> >> >
> >>
> >> Please don't forget to build-test this series for IA32 too.
> >>
> >> Thanks
> >> Laszlo
> >>
> >>
> >
> >
> >