Re: [PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page setup for APs

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

You're right. It will be updated to use more accurate wording. Thanks for catching it.

Regards,
Jian


> -----Original Message-----
> From: Yao, Jiewen
> Sent: Friday, December 22, 2017 1:22 PM
> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> Cc: Laszlo Ersek <lersek@redhat.com>; Dong, Eric <eric.dong@intel.com>
> Subject: RE: [edk2] [PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page
> setup for APs
> 
> I do not think we have AP guard page before, right?
> So I suggest we change commit message to be: Add missing Guard page setup
> for APs.
> 
> With commit message update, reviewed-by: Jiewen.yao@intel.com
> 
> 
> > -----Original Message-----
> > From: Wang, Jian J
> > Sent: Friday, December 22, 2017 12:26 PM
> > To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> > Cc: Laszlo Ersek <lersek@redhat.com>; Yao, Jiewen <jiewen.yao@intel.com>;
> > Dong, Eric <eric.dong@intel.com>
> > Subject: RE: [edk2] [PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page
> > setup for APs
> >
> > Hi,
> >
> > Anyone has any comments on this?
> >
> > Regards,
> > Jian
> >
> >
> > > -----Original Message-----
> > > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Jian
> > J
> > > Wang
> > > Sent: Thursday, December 21, 2017 9:27 AM
> > > To: edk2-devel@lists.01.org
> > > Cc: Laszlo Ersek <lersek@redhat.com>; Yao, Jiewen
> <jiewen.yao@intel.com>;
> > > Dong, Eric <eric.dong@intel.com>
> > > Subject: [edk2] [PATCH] UefiCpuPkg/MpInitLib: Fix incorrect Guard page
> setup
> > > for APs
> > >
> > > AP has its own stack for code execution. If PcdCpuStackGuard is enabled,
> > > the page at the bottom of stack of AP will be disabled (NOT PRESENT) to
> > > monitor the stack overflow issue. This requires PcdCpuApStackSize to be
> > > set with value more than one page of memory.
> > >
> > > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > > Cc: Eric Dong <eric.dong@intel.com>
> > > Cc: Laszlo Ersek <lersek@redhat.com>
> > > Contributed-under: TianoCore Contribution Agreement 1.1
> > > Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> > > ---
> > >  UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |  1 +
> > >  UefiCpuPkg/Library/MpInitLib/DxeMpLib.c       | 34
> > > ++++++++++++++++++++++++---
> > >  2 files changed, 32 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> > > b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> > > index 805641b516..e7b9eb4462 100644
> > > --- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> > > +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
> > > @@ -73,4 +73,5 @@
> > >    gUefiCpuPkgTokenSpaceGuid.PcdCpuMicrocodePatchRegionSize
> > ##
> > > CONSUMES
> > >    gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode
> > ## CONSUMES
> > >    gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate
> > ##
> > > SOMETIMES_CONSUMES
> > > +  gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard
> > ##
> > > CONSUMES
> > >
> > > diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> > > b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> > > index 479f8189f6..40c1bf407a 100644
> > > --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> > > +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> > > @@ -17,6 +17,7 @@
> > >  #include <Library/UefiLib.h>
> > >  #include <Library/UefiBootServicesTableLib.h>
> > >  #include <Library/DebugAgentLib.h>
> > > +#include <Library/DxeServicesTableLib.h>
> > >
> > >  #include <Protocol/Timer.h>
> > >
> > > @@ -288,9 +289,12 @@ InitMpGlobalData (
> > >    IN CPU_MP_DATA               *CpuMpData
> > >    )
> > >  {
> > > -  EFI_STATUS                 Status;
> > > -  EFI_PHYSICAL_ADDRESS       Address;
> > > -  UINTN                      ApSafeBufferSize;
> > > +  EFI_STATUS                          Status;
> > > +  EFI_PHYSICAL_ADDRESS                Address;
> > > +  UINTN                               ApSafeBufferSize;
> > > +  UINTN                               Index;
> > > +  EFI_GCD_MEMORY_SPACE_DESCRIPTOR     MemDesc;
> > > +  UINTN                               StackBase;
> > >
> > >    SaveCpuMpData (CpuMpData);
> > >
> > > @@ -301,6 +305,30 @@ InitMpGlobalData (
> > >      return;
> > >    }
> > >
> > > +  if (PcdGetBool (PcdCpuStackGuard)) {
> > > +    //
> > > +    // One extra page at the bottom of the stack is needed for Guard page.
> > > +    //
> > > +    if (CpuMpData->CpuApStackSize <= EFI_PAGE_SIZE) {
> > > +      DEBUG ((DEBUG_ERROR, "PcdCpuApStackSize is not big enough for
> > Stack
> > > Guard!\n"));
> > > +      ASSERT (FALSE);
> > > +    }
> > > +
> > > +    for (Index = 0; Index < CpuMpData->CpuCount; ++Index) {
> > > +      StackBase = CpuMpData->Buffer + Index *
> > CpuMpData->CpuApStackSize;
> > > +
> > > +      Status = gDS->GetMemorySpaceDescriptor (StackBase, &MemDesc);
> > > +      ASSERT_EFI_ERROR (Status);
> > > +
> > > +      Status = gDS->SetMemorySpaceAttributes (
> > > +                      StackBase,
> > > +                      EFI_PAGES_TO_SIZE (1),
> > > +                      MemDesc.Attributes | EFI_MEMORY_RP
> > > +                      );
> > > +      ASSERT_EFI_ERROR (Status);
> > > +    }
> > > +  }
> > > +
> > >    //
> > >    // Avoid APs access invalid buffer data which allocated by BootServices,
> > >    // so we will allocate reserved data for AP loop code. We also need to
> > > --
> > > 2.15.1.windows.2
> > >
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