Re: [PATCH 0/6] MdeModulePkg/VariableSmm: fix MOR / MorLock inconsistency

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

Thanks. Laszlo.
This patch looks good to me in general.

One minor comment is below:
MorLockInitAtEndOfDxe()
+  if (!mMorLockInitializationRequired) {
+    //
+    // The EFI_SMM_FAULT_TOLERANT_WRITE_PROTOCOL has never been installed, thus
+    // the variable write service is unavailable. Do nothing.
+    //
+    return;
+  }
I think it is an illegal case. I would add ASSERT before return.


And I hope Ladi can help us double confirm if this patch fixed the device guard problem. :-)

Thank you
Yao Jiewen


> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Wednesday, October 4, 2017 5:28 AM
> To: edk2-devel-01 <edk2-devel@lists.01.org>
> Cc: Dong, Eric <eric.dong@intel.com>; Yao, Jiewen <jiewen.yao@intel.com>; Ladi
> Prosek <lprosek@redhat.com>; Zeng, Star <star.zeng@intel.com>
> Subject: [PATCH 0/6] MdeModulePkg/VariableSmm: fix MOR / MorLock
> inconsistency
> 
> Repo:   https://github.com/lersek/edk2.git
> Branch: mor_lock_init_at_end_of_dxe
> 
> This patch set fixes the issue reported in the following items:
> 
> * Inconsistent MOR control variables exposed by OVMF, breaks Windows
>   Device Guard
> 
>   https://bugzilla.redhat.com/show_bug.cgi?id=1496170
> 
> * VariableSmm MorLockInit(): create MORLock only if / after MOR exists
> 
>   https://bugzilla.tianocore.org/show_bug.cgi?id=727
> 
> Patches #1 through #3 are cleanups.
> 
> Patch #4 is a small helper patch for patch #5.
> 
> Patch #5 is the actual fix, following Jiewen's suggestions from the
> edk2-devel thread
> 
> * [edk2] multiple levels of support for MOR / MORLock
> 
>   https://lists.01.org/pipermail/edk2-devel/2017-September/015444.html
>   https://lists.01.org/pipermail/edk2-devel/2017-October/015530.html
> 
> Patch #6 is a workaround for some OSes (minimally Fedora 24-26, and some
> Debian versions) that create the MOR variable even if the platform
> doesn't offer it up-front. This patch also follows Jiewen's suggestion
> from the same edk2-devel thread.
> 
> (
> 
> BTW, at Paolo's recommendation, I've now reported this kernel issue for
> Fedora, under
> 
> * incorrect downstream-only Platform Reset Attack Mitigation patch in
>   the F24-F26 kernels
> 
>   https://bugzilla.redhat.com/show_bug.cgi?id=1498159
> 
> )
> 
> I've checked this set for basic regressions, using OVMF, normal boot and
> S3 suspend/resume:
> 
> * Q35, SMM, IA32:
>   - Fedora 25 -- verified patch #6 specifically
> 
> * i440fx, no SMM, X64:
>   - Fedora 24
> 
> * Q35, SMM, IA32X64:
>   - Fedora 26 -- verified patch #6 specifically
>   - Windows 7
>   - Windows 8.1
>   - Windows 10
>   - Windows Server 2008 R2
>   - Windows Server 2012 R2
> 
> I didn't / couldn't test this set in the following two environments:
> 
> - on platforms where TcgMor.inf is included in the firmware, and the MOR
>   variable exists genuinely,
> 
> - in the nested virt setup where Ladi reported the Device Guard
>   breakage. (If I understand correctly, ATM this requires additional
>   host kernel (KVM) patches.)
> 
> Test results / feedback from those envs would be appreciated.
> 
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Ladi Prosek <lprosek@redhat.com>
> Cc: Star Zeng <star.zeng@intel.com>
> 
> Thanks,
> Laszlo
> 
> Laszlo Ersek (6):
>   MdeModulePkg/Variable/RuntimeDxe: move SecureBootHook() decl to new
>     header
>   MdeModulePkg/Variable/RuntimeDxe: move MOR func. declarations to
>     header
>   MdeModulePkg/Variable/RuntimeDxe: introduce MorLockInitAtEndOfDxe()
>     hook
>   MdeModulePkg/Variable/RuntimeDxe: permit MorLock deletion for passthru
>     req
>   MdeModulePkg/Variable/RuntimeDxe: delay MorLock creation until
>     EndOfDxe
>   MdeModulePkg/Variable/RuntimeDxe: delete and lock OS-created MOR
>     variable
> 
>  MdeModulePkg/Universal/Variable/RuntimeDxe/Measurement.c
> |   2 +
>  MdeModulePkg/Universal/Variable/RuntimeDxe/PrivilegePolymorphic.h    |
> 89 ++++++++++
>  MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockDxe.c
> |  45 +++--
>  MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c
> | 173 ++++++++++++++++++--
>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c                |
> 51 ------
>  MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.h                |
> 2 +
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableDxe.c             |
> 2 +
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe.inf    |
> 1 +
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.c
> |   2 +
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmm.inf
> |   4 +
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
> |  16 +-
>  MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.inf
> |   1 +
>  12 files changed, 294 insertions(+), 94 deletions(-)
>  create mode 100644
> MdeModulePkg/Universal/Variable/RuntimeDxe/PrivilegePolymorphic.h
> 
> --
> 2.14.1.3.gb7cf6e02401b