Re: [PATCH] MdeModulePkg/CapsulePei: clean Dcache before consuming capsule data

["Yao, Jiewen" <jiewen.yao@intel.com>]

Thanks. Please also include the note in the final commit message.

Reviewed-by: Jiewen.yao@intel.com


> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Ard
> Biesheuvel
> Sent: Wednesday, June 6, 2018 5:10 AM
> To: edk2-devel@lists.01.org
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>;
> Gao, Liming <liming.gao@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Leif
> Lindholm <leif.lindholm@linaro.org>; Kinney, Michael D
> <michael.d.kinney@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH] MdeModulePkg/CapsulePei: clean Dcache before
> consuming capsule data
> 
> On 6 June 2018 at 11:52, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> > When capsule updates are staged for processing after a warm reboot,
> > they are copied into memory with the MMU and caches enabled. When
> > the capsule PEI gets around to coalescing the capsule, the MMU and
> > caches may still be disabled, and so on architectures where uncached
> > accesses are incoherent with the caches (such as ARM and AARCH64),
> > we may read stale data if we don't clean the caches to memory first.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> 
> Leif asked me to include a note why this cannot be done when
> UpdateCapsule() is called.
> 
> 
> """
> Note that this cache maintenance cannot be done during the invocation
> of UpdateCapsule(), since the ScatterGatherList structures are only
> identified by physical address, and at runtime, the firmware doesn't
> know whether and where this memory is mapped, and cache maintenance
> requires a virtual address.
> """
> 
> > ---
> >  MdeModulePkg/Universal/CapsulePei/CapsulePei.inf           | 1 +
> >  MdeModulePkg/Universal/CapsulePei/Common/CapsuleCoalesce.c | 4 ++++
> >  2 files changed, 5 insertions(+)
> >
> > diff --git a/MdeModulePkg/Universal/CapsulePei/CapsulePei.inf
> b/MdeModulePkg/Universal/CapsulePei/CapsulePei.inf
> > index c54bc21a95a8..594e110d1f8a 100644
> > --- a/MdeModulePkg/Universal/CapsulePei/CapsulePei.inf
> > +++ b/MdeModulePkg/Universal/CapsulePei/CapsulePei.inf
> > @@ -48,6 +48,7 @@ [Packages]
> >
> >  [LibraryClasses]
> >    BaseLib
> > +  CacheMaintenanceLib
> >    HobLib
> >    BaseMemoryLib
> >    PeiServicesLib
> > diff --git a/MdeModulePkg/Universal/CapsulePei/Common/CapsuleCoalesce.c
> b/MdeModulePkg/Universal/CapsulePei/Common/CapsuleCoalesce.c
> > index 3e7054cd38a9..1730f925adc5 100644
> > --- a/MdeModulePkg/Universal/CapsulePei/Common/CapsuleCoalesce.c
> > +++ b/MdeModulePkg/Universal/CapsulePei/Common/CapsuleCoalesce.c
> > @@ -27,6 +27,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY
> KIND, EITHER EXPRESS OR IMPLIED.
> >  #include <Guid/CapsuleVendor.h>
> >
> >  #include <Library/BaseMemoryLib.h>
> > +#include <Library/CacheMaintenanceLib.h>
> >  #include <Library/DebugLib.h>
> >  #include <Library/PrintLib.h>
> >  #include <Library/BaseLib.h>
> > @@ -283,6 +284,9 @@ ValidateCapsuleByMemoryResource (
> >        DEBUG ((EFI_D_INFO, "Address(0x%lx) Size(0x%lx) in
> MemoryResource[0x%x] - Start(0x%lx) Length(0x%lx)\n",
> >                            Address, Size,
> >                            Index, MemoryResource[Index].PhysicalStart,
> MemoryResource[Index].ResourceLength));
> > +
> > +      WriteBackDataCacheRange ((VOID *)(UINTN)Address, Size);
> > +
> >        return TRUE;
> >      }
> >    }
> > --
> > 2.17.0
> >
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