This adds support for FVB in order to support a platform independent
and non-volatile variable store on UefiPayloadPkg. The variable store
makes use the SmmStoreLib to provide an unauthenticed variable store.
Since commit bc744f5893fc4d53275ed26dd8d968011c6a09c1 coreboot supports
the SMMSTORE v2 feature. It implements a SMI handler that is able to
write, read and erase pages in the boot media (SPI flash).
The communication is done using a fixed communication buffer that is
allocated in CBMEM. The existence of this optional feature is advertised
by a coreboot table.
When the SMMSTORE feature is not available the variable emulation is used
by setting PcdEmuVariableNvModeEnable to TRUE.
The DXE component provides runtime services and takes care of virtual to
physical mapping the communication buffers between SMM and OS.
The contents of the variable store can be accessed and modified by any
priviledged application. As authentication is done by runtime services
only the store shouldn't be used to store authenticated variables.
Tested on Linux and Windows 10 on real hardware.
Currently this cannot be tested on coreboot and qemu as it doesn't support
the SMMSTORE on qemu.
Cc: Guo Dong <guo.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Maurice Ma <maurice.ma@intel.com>
Cc: Benjamin You <benjamin.you@intel.com>
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Change-Id: I79a234275e25961869edf959cfbf4f8d17df2383
