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

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

I haven't got time to do it in automatic way. V1 may need a shell app to
check it, but current implementation might not need it because we now
have 2 or 3 continuous 2MB pages to hold all page tables. We just
need to verify the page attribute of those 2 or 3 page tables. It's easy
to do it in a JTAG debugger manually.

> -----Original Message-----
> From: Yao, Jiewen
> Sent: Tuesday, December 05, 2017 10:32 AM
> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> Cc: Yao, Jiewen <jiewen.yao@intel.com>
> Subject: RE: [edk2] [PATCH v2 0/4] Enable page table write protection
> 
> Hi Jian
> In V1 review, I suggest to test in UEFI shell env to make sure all page table is
> read only, with PageTable split in CPU driver.
> 
> May I know if that is done?
> 
> Thank you
> Yao Jiewen
> 
> > -----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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