Re: [PATCH] ArmVirtPkg/ArmVirtQemu: use non-accelerated CopyMem for VariableRuntimeDxe

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 16 November 2017 at 01:01, Shannon Zhao <zhaoshenglong@huawei.com> wrote:
>
>
> On 2017/11/15 22:03, Ard Biesheuvel wrote:
>> On 15 November 2017 at 13:51, Laszlo Ersek <lersek@redhat.com> wrote:
>>> > On 11/14/17 11:22, Ard Biesheuvel wrote:
>>>> >> The VariableRuntimeDxe driver may use CopyMem () on NOR flash regions,
>>>> >> assuming such regions always have full memory semantics. Given that
>>>> >> those regions cannot be mapped as ordinary memory on ARM (due to the
>>>> >> fact that the NOR flash requires device semantics while in write mode)
>>>> >> this prevents us from using BaseMemoryLibOptDxe in VariableRuntimeDxe,
>>>> >> since it may use unaligned accesses and/or DC ZVA instructions, both
>>>> >> of which are incompatible with mappings using device semantics.
>>>> >>
>>>> >> Note that there is no way we can work around this by changing the
>>>> >> mapping type between 'memory' and 'device' when switching from read to
>>>> >> write mode and back, because the runtime mapping is created by the OS,
>>>> >> and cannot be changed at will.
>>>> >>
>>>> >> So let's just switch to the unaccelerated version of BaseMemoryLib which
>>>> >> does not have the same problem.
>>>> >>
>>>> >> Contributed-under: TianoCore Contribution Agreement 1.1
>>>> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> >> ---
>>>> >>  ArmVirtPkg/ArmVirtQemu.dsc       | 2 ++
>>>> >>  ArmVirtPkg/ArmVirtQemuKernel.dsc | 2 ++
>>>> >>  2 files changed, 4 insertions(+)
>>>> >>
>>>> >> diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc
>>>> >> index 8a60b61f2aa6..7b220d6e3c31 100644
>>>> >> --- a/ArmVirtPkg/ArmVirtQemu.dsc
>>>> >> +++ b/ArmVirtPkg/ArmVirtQemu.dsc
>>>> >> @@ -261,6 +261,8 @@ [Components.common]
>>>> >>    MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf {
>>>> >>      <LibraryClasses>
>>>> >>        NULL|MdeModulePkg/Library/VarCheckUefiLib/VarCheckUefiLib.inf
>>>> >> +      # don't use unaligned CopyMem () on the UEFI varstore NOR flash region
>>>> >> +      BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
>>>> >>    }
>>>> >>  !if $(SECURE_BOOT_ENABLE) == TRUE
>>>> >>    MdeModulePkg/Universal/SecurityStubDxe/SecurityStubDxe.inf {
>>>> >> diff --git a/ArmVirtPkg/ArmVirtQemuKernel.dsc b/ArmVirtPkg/ArmVirtQemuKernel.dsc
>>>> >> index 9a31ec93ca06..7c032e1b07e0 100644
>>>> >> --- a/ArmVirtPkg/ArmVirtQemuKernel.dsc
>>>> >> +++ b/ArmVirtPkg/ArmVirtQemuKernel.dsc
>>>> >> @@ -252,6 +252,8 @@ [Components.common]
>>>> >>    MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf {
>>>> >>      <LibraryClasses>
>>>> >>        NULL|MdeModulePkg/Library/VarCheckUefiLib/VarCheckUefiLib.inf
>>>> >> +      # don't use unaligned CopyMem () on the UEFI varstore NOR flash region
>>>> >> +      BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
>>>> >>    }
>>>> >>  !if $(SECURE_BOOT_ENABLE) == TRUE
>>>> >>    MdeModulePkg/Universal/SecurityStubDxe/SecurityStubDxe.inf {
>>>> >>
>>> >
>>> > Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>> >
>>> > Given that we've never seen the symptom reported by Shannon, I must
>>> > think Shannon is using some kind of new hardware. May I ask what
>>> > hardware that is?
>>> >
>> I think this is equally likely to occur in any KVM hardware
>> virtualization context. It is simply a regression after moving to the
>> OptDxe BaseMemoryLib flavor.
>
> Exactly. I'm using Huawei D05. It works well when I use a older edk2
> while fails when updating to UDK2017 branch.
>
> Tested-by: Shannon Zhao <zhaoshenglong@huawei.com>
>

Pushed as 44d71c217ccb

Thanks.