On a MM system, the main UEFI variable logic resides in MMRAM. In
that case, the variable policy logic in `VarCheckPolicyLib`, such as
`VarCheckPolicyLibStandaloneMm` is linked against the MM driver also
in that case `VariableStandaloneMm`.
The MM variable driver indicates its presence to the RT DXE driver
via `gEfiSmmVariableProtocolGuid` to indicate variable read support
is available from MM. This triggers installation of the variable
architectural protocol in DXE.
Today, variable policy is initialized by calling
`VariablePolicySmmDxeMain()` in `VariableSmmRuntimeInitialize()`. In
turn, this installs `gEdkiiVariablePolicyProtocolGuid`. Functions in
`gEdkiiVariablePolicyProtocolGuid` may trigger MMIs. However, it is
possible that the MM variable driver which is linked against the code
with the variable policy MMI handlers (i.e. `VarCheckPolicyLib`) is
not loaded yet.
Therefore, this change moves invocation of
`VariablePolicySmmDxeMain()` to `SmmVariableReady()` which is called
on installation of `gEfiSmmVariableProtocolGuid` indicating variable
MM services are ready. `gEdkiiVariablePolicyProtocolGuid` is still
installed prior to the variable architectural protocol being
installed.
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
1428b94fc0