OvmfPkg/SmmAccess: close and lock SMRAM at default SMBASE
During normal boot, when EFI_DXE_SMM_READY_TO_LOCK_PROTOCOL is installed
by platform BDS, the SMM IPL locks SMRAM (TSEG) through
EFI_SMM_ACCESS2_PROTOCOL.Lock(). See SmmIplReadyToLockEventNotify() in
"MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c".
During S3 resume, S3Resume2Pei locks SMRAM (TSEG) through
PEI_SMM_ACCESS_PPI.Lock(), before executing the boot script. See
S3ResumeExecuteBootScript() in
"UefiCpuPkg/Universal/Acpi/S3Resume2Pei/S3Resume.c".
Those are precisely the places where the SMRAM at the default SMBASE
should be locked too. Add such an action to SmramAccessLock().
Notes:
- The SMRAM at the default SMBASE doesn't support the "closed and
unlocked" state (and so it can't be closed without locking it, and it
cannot be opened after closing it).
- The SMRAM at the default SMBASE isn't (and shouldn't) be exposed with
another EFI_SMRAM_DESCRIPTOR in the GetCapabilities() members of
EFI_SMM_ACCESS2_PROTOCOL / PEI_SMM_ACCESS_PPI. That's because the SMRAM
in question is not "general purpose"; it's only QEMU's solution to
protect the initial SMI handler from the OS, when a VCPU is hot-plugged.
Consequently, the state of the SMRAM at the default SMBASE is not
reflected in the "OpenState" / "LockState" fields of the protocol and
PPI.
- An alternative to extending SmramAccessLock() would be to register an
EFI_DXE_SMM_READY_TO_LOCK_PROTOCOL notify in SmmAccess2Dxe (for locking
at normal boot), and an EDKII_S3_SMM_INIT_DONE_GUID PPI notify in
SmmAccessPei (for locking at S3 resume).
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Message-Id: <
20200129214412.2361-10-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>