The DecompressMemFvs() function in "OvmfPkg/Sec/SecMain.c" uses more
memory, temporarily, than what PEIFV and DXEFV will ultimately need.
First, it uses an output buffer for decompression, second, the
decompression itself needs a scratch buffer (and this scratch buffer is
the highest area that SEC uses).
DecompressMemFvs() used to be called on normal boots only (ie. not on S3
resume), which is why the decompression output buffer and the scratch
buffer were allowed to scribble over RAM. However, we'll soon start to
worry during S3 resume that the runtime OS might tamper with the
pre-decompressed PEIFV, and we'll decompress the firmware volumes on S3
resume too, from pristine flash. For this we'll need to know the end of
the scratch buffer in advance, so we can prepare a non-malicious OS for
it.
Calculate the end of the scratch buffer statically in the FDF files, and
assert in DecompressMemFvs() that the runtime decompression will match it.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19036 6f19259b-4bc3-4df7-8a09-765794883524
OVMF_VARS.fd and OVMF_CODE.fd split the variable store and the firmware
code in separate files.
The PCDs' values continue to depend only on FD_SIZE_1MB vs. FD_SIZE_2MB.
With the split files, it must be ensured on the QEMU command line that
OVMF_VARS.fd and OVMF_CODE.fd be contiguously mapped so that they end
exactly at 4GB. See QEMU commit 637a5acb (first released in v2.0.0).
In this patch we must take care to assign each PCD only once.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15670 6f19259b-4bc3-4df7-8a09-765794883524
Laszlo Ersek