Re: [PATCH v2 0/4] Enable page table write protection

["Wang, Jian J" <jian.j.wang@intel.com>]

It's for sharing the pool between the DxeIpl and CpuDxe. If we don't care about 
wasting a little bit memory, it's ok to drop this definition. CpuDxe can reserve
a block of memory for page table for its own uses.

> -----Original Message-----
> From: Yao, Jiewen
> Sent: Tuesday, December 05, 2017 10:27 AM
> To: Wang, Jian J <jian.j.wang@intel.com>; Zeng, Star <star.zeng@intel.com>;
> edk2-devel@lists.01.org
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Dong, Eric <eric.dong@intel.com>
> Subject: RE: [edk2] [PATCH v2 0/4] Enable page table write protection
> 
> I do not suggest we define PAGE_TABLE_POOL_HEADER.
> If we can figure out other way, that will be better.
> 
> Thank you
> Yao Jiewen
> 
> 
> > -----Original Message-----
> > From: Wang, Jian J
> > Sent: Monday, December 4, 2017 5:26 PM
> > To: Zeng, Star <star.zeng@intel.com>; edk2-devel@lists.01.org
> > Cc: Yao, Jiewen <jiewen.yao@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>;
> Dong,
> > Eric <eric.dong@intel.com>
> > Subject: RE: [edk2] [PATCH v2 0/4] Enable page table write protection
> >
> > That means we can't share page table pool between DxeIpl and CpuDxe. If this
> is
> > acceptable, I can remove them.
> >
> > > -----Original Message-----
> > > From: Zeng, Star
> > > Sent: Monday, December 04, 2017 5:11 PM
> > > To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> > > Cc: Yao, Jiewen <jiewen.yao@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>;
> > Dong,
> > > Eric <eric.dong@intel.com>; Zeng, Star <star.zeng@intel.com>
> > > Subject: RE: [edk2] [PATCH v2 0/4] Enable page table write protection
> > >
> > > Recommend to not introduce the new header file and PCDs as new
> interfaces,
> > > but handle the page table pool separately in DxeIpl and CpuDxe.
> > >
> > > Thanks,
> > > Star
> > > -----Original Message-----
> > > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Jian
> > J
> > > Wang
> > > Sent: Monday, December 4, 2017 4:36 PM
> > > To: edk2-devel@lists.01.org
> > > Subject: [edk2] [PATCH v2 0/4] Enable page table write protection
> > >
> > > > v2 changes:
> > > >  a. Enable protection on any newly added page table after DxeIpl.
> > > >  b. Introduce page table pool concept to make page table allocation
> > > >     and protection easier and error free.
> > >
> > > Write Protect feature (CR0.WP) is always enabled in driver
> > UefiCpuPkg/CpuDxe.
> > > But the memory pages used for page table are not set as read-only in the
> driver
> > > DxeIplPeim, after the paging is setup. This might jeopardize the page table
> > > integrity if there's buffer overflow occured in other part of system.
> > >
> > > This patch series will change this situation by clearing R/W bit in page
> attribute
> > > of the pages used as page table.
> > >
> > > Validation works include booting Windows (10/server 2016) and Linux
> > > (Fedora/Ubuntu) on OVMF and Intel real platform.
> > >
> > > Jian J Wang (4):
> > >   MdeModulePkg/MdeModulePkg.dec: Add new PCDs and Guid
> > >   MdeModulePkg/PageTablePool.h: Page table pool GUID definition file
> > >   MdeModulePkg/DxeIpl: Mark page table as read-only
> > >   UefiCpuPkg/CpuDxe: Enable protection for newly added page table
> > >
> > >  MdeModulePkg/Core/DxeIplPeim/DxeIpl.h            |  34 +++
> > >  MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf          |   3 +
> > >  MdeModulePkg/Core/DxeIplPeim/Ia32/DxeLoadFunc.c  |   8 +-
> > >  MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 315
> > > +++++++++++++++++++++-
> > > MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.h |  15 ++
> > >  MdeModulePkg/Include/Guid/PageTablePool.h        |  53 ++++
> > >  MdeModulePkg/MdeModulePkg.dec                    |  28 ++
> > >  UefiCpuPkg/CpuDxe/CpuDxe.c                       |  17 +-
> > >  UefiCpuPkg/CpuDxe/CpuDxe.h                       |   2 +
> > >  UefiCpuPkg/CpuDxe/CpuDxe.inf                     |   3 +
> > >  UefiCpuPkg/CpuDxe/CpuPageTable.c                 | 329
> > > ++++++++++++++++++++++-
> > >  UefiCpuPkg/CpuDxe/CpuPageTable.h                 |  22 ++
> > >  12 files changed, 816 insertions(+), 13 deletions(-)  create mode 100644
> > > MdeModulePkg/Include/Guid/PageTablePool.h
> > >
> > > --
> > > 2.14.1.windows.1
> > >
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