Re: [PATCH v8 3/6] UefiCpuPkg/SmmBaseHob.h: Add SMM Base HOB Data

["Wu, Jiaxin" <jiaxin.wu@intel.com>]

Thanks Ray, I will update all you mentioned.



> -----Original Message-----
> From: Ni, Ray <ray.ni@intel.com>
> Sent: Thursday, February 16, 2023 12:59 PM
> To: Wu, Jiaxin <jiaxin.wu@intel.com>; devel@edk2.groups.io
> Cc: Dong, Eric <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>;
> Laszlo Ersek <lersek@redhat.com>; Gerd Hoffmann <kraxel@redhat.com>;
> Kumar, Rahul R <rahul.r.kumar@intel.com>
> Subject: RE: [PATCH v8 3/6] UefiCpuPkg/SmmBaseHob.h: Add SMM Base HOB
> Data
> 
> 
> 
> > -----Original Message-----
> > From: Wu, Jiaxin <jiaxin.wu@intel.com>
> > Sent: Thursday, February 16, 2023 10:47 AM
> > To: devel@edk2.groups.io
> > Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Zeng, Star
> > <star.zeng@intel.com>; Laszlo Ersek <lersek@redhat.com>; Gerd Hoffmann
> > <kraxel@redhat.com>; Kumar, Rahul R <rahul.r.kumar@intel.com>
> > Subject: [PATCH v8 3/6] UefiCpuPkg/SmmBaseHob.h: Add SMM Base HOB
> > Data
> >
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4337
> >
> > The default SMBASE for the x86 processor is 0x30000. When
> > SMI happens, CPU runs the SMI handler at SMBASE+0x8000.
> > Also, the SMM save state area is within SMBASE+0x10000.
> >
> > One of the SMM initialization from CPU perspective is to relocate
> > and program the new SMBASE (in TSEG range) for each CPU thread. When
> > the SMBASE relocation happens in a PEI module, the PEI module shall
> > produce the SMM_BASE_HOB in HOB database which tells the
> > PiSmmCpuDxeSmm driver (runs at a later phase) about the new SMBASE
> > for each CPU thread. PiSmmCpuDxeSmm driver installs the SMI handler
> > at the SMM_BASE_HOB.SmBase[Index]+0x8000 for CPU thread Index. When
> > the HOB doesn't exist, PiSmmCpuDxeSmm driver shall relocate and
> > program the new SMBASE itself.
> >
> > This patch adds the SMM Base HOB for any PEI module to do
> > the SmBase relocation ahead of PiSmmCpuDxeSmm driver and
> > store the relocated SmBase address in array for reach
> > Processors.
> >
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Zeng Star <star.zeng@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Cc: Gerd Hoffmann <kraxel@redhat.com>
> > Cc: Rahul Kumar <rahul1.kumar@intel.com>
> > Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
> > ---
> >  UefiCpuPkg/Include/Guid/SmmBaseHob.h | 75
> > ++++++++++++++++++++++++++++++++++++
> >  UefiCpuPkg/UefiCpuPkg.dec            |  5 ++-
> >  2 files changed, 79 insertions(+), 1 deletion(-)
> >  create mode 100644 UefiCpuPkg/Include/Guid/SmmBaseHob.h
> >
> > diff --git a/UefiCpuPkg/Include/Guid/SmmBaseHob.h
> > b/UefiCpuPkg/Include/Guid/SmmBaseHob.h
> > new file mode 100644
> > index 0000000000..9434276991
> > --- /dev/null
> > +++ b/UefiCpuPkg/Include/Guid/SmmBaseHob.h
> > @@ -0,0 +1,75 @@
> > +/** @file
> > +  The Smm Base HOB is used to store the information of:
> > +  * The relocated SmBase address in array for each Processors.
> 
> 1. Processors -> processor.
> 
> > + CPU runs the SMI handler at Smbase+0x8000. Also, the SMM save state
> area is
> 
> 2. better align the term to use processor.
> MP protocol also uses the term "processor"
> 
> > +
> > +  Note:
> > +  1. Smbase relocation process needs to program the vender specific
> > hardware
> > +  interface to set Smbase, it should be in the thread scope. It's doable to
> 
> 3. "it should be in the thread scope" -> "it might be in the thread scope".
> The HOB itself doesn't have "thread scope" requirement.
> With the "thread scope" possibility, following statement looks good to me.
> Just change "should be" to "might be".
> 
> > +#pragma pack(1)
> > +typedef struct {
> > +  ///
> > +  /// CpuIndex tells which CPU range this specific HOB instance described.
> > +  /// If CpuIndex is set to 0, it indicats the HOB describes the CPU from 0 to
> > +  /// NumberOfCpus - 1. The HOB list may contains multiple this HOB
> > instances.
> > +  /// Each HOB instances describe the information for CPU from CpuIndex to
> > +  /// CpuIndex + NumberOfCpus - 1. The instance order in the HOB list is
> > random
> > +  /// so consumer can not assume the CpuIndex of first instance is 0.
> > +  ///
> > +  UINT32    CpuIndex;
> 
> 4. "ProcessorIndex". Please also update the comments to use "processor".