Our UEFI guest firmware takes ownership of the emulated NOR flash in
order to support the variable runtime services, and it does not expect
the OS to interfere with the underlying storage directly. So disable
the NOR flash DT nodes as we discover them, in a way similar to how we
disable the PL031 RTC in the device tree when we attach our RTC runtime
driver to it.
Note that this also hides the NOR flash bank that carries the UEFI
executable code, but this is not intended to be updatable from inside
the guest anyway, and if it was, we should use capsule update to do so.
Also, the first -pflash argument that defines the backing for this flash
bank is often issued with the 'readonly' modifier, in order to prevent
any changes whatsoever to be made to the executable firmware image by
the guest.
This issue has become relevant due to the following Linux changes,
which enable the flash driver stack for default build configurations
targetting arm64 and 32-bit ARM.
ce693fc2a877
("arm64: defconfig: Enable flash device drivers for QorIQ boards", 2020-03-16).
5f068190cc10
("ARM: multi_v7_defconfig: Enable support for CFI NOR FLASH", 2019-04-03)
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
The primary FV contains the firmware boot image, which is not
runtime updatable in our case. So exposing it to the NOR flash
driver is undesirable, since it may attempt to modify the NOR
flash contents. It is also rather pointless, since we don't
keep anything there that we care to expose. (the SEC and PEI
phase modules are not executable from DXE context, and the
contents of the embedded DXE phase FV are exposed by the DXE
core directly via the FVB2 protocol)
So let's disregard the NOR flash block that covers the primary
FV.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
NorFlashQemuLib is one of the last remaining drivers in ArmVirtPkg
that are not based on the device tree received from QEMU.
For ArmVirtQemu, this does not really matter, given that the NOR
flash banks are always the same: the PEI code is linked to execute
in place from flash bank #0, and the fixed varstore PCDs refer to
flash bank #1 directly.
However, ArmVirtQemuKernel can execute at any offset, permitting it
to be used as an intermediary loader when running QEMU with secure
world emulation enabled, in which case NOR flash bank #0 is secure
only and contains the secure world firmware. In this case,
NorFlashQemuLib should not expose the first flash bank at all.
To prevent introducing too much internal knowledge about which flash
bank is accessible under which circumstances, let's switch to using
the DTB to decide which flash banks to expose to the NOR flash driver.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Now that the PL031 RTC driver library no longer depends on the ARM
platform specific ArmPlatformSysConfigLib, we no longer need to
implement ArmPlatform.h or have a resolution for that library.
This allows us to get rid of a rather dodgy practice of including
platform headers using compiler flags, which is a bad idea at various
levels.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Ard Biesheuvel
Michael D Kinney
Ard Biesheuvel
Laszlo Ersek
Olivier Martin