Alexandre Ghiti 8153b2622b platform/lib: Set no-map attribute on all PMP regions ... This reverts commit 6966ad0abe ("platform/lib: Allow the OS to map the regions that are protected by PMP"). It was thought at the time of this commit that allowing the kernel to map PMP protected regions was safe but it is actually not: for example, the hibernation process will try to access any linear mapping page and then will fault on such mapped PMP regions [1]. Another issue is that the device tree specification [2] states that a !no-map region must be declared as EfiBootServicesData/Code in the EFI memory map which would make the PMP protected regions reclaimable by the kernel. And to circumvent this, RISC-V edk2 diverges from the DT specification to declare those regions as EfiReserved. The no-map attribute was removed to allow the kernel to use hugepages larger than 2MB to map the linear mapping to improve the performance but actually a recent talk from Mike Rapoport [3] stated that the performance benefit was marginal. For all those reasons, let's mark all the PMP protected regions as "no-map". [1] https://lore.kernel.org/linux-riscv/CAAYs2=gQvkhTeioMmqRDVGjdtNF_vhB+vm_1dHJxPNi75YDQ_Q@mail.gmail.com/ [2] "3.5.4 /reserved-memory and UEFI" https://github.com/devicetree-org/devicetree-specification/releases/download/v0.4-rc1/devicetree-specification-v0.4-rc1.pdf [3] https://lwn.net/Articles/931406/ Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Reviewed-by: Atish Patra <atishp@rivosinc.com> Reviewed-by: Xiang W <wxjstz@126.com>		2023-06-15 18:27:17 +05:30
..
fu540.c	platform/lib: Set no-map attribute on all PMP regions	2023-06-15 18:27:17 +05:30
fu740.c	treewide: Replace TRUE/FALSE with true/false	2023-01-06 17:26:35 +05:30
objects.mk	platform: generic: Use kconfig for enabling/disabling overrides	2022-08-08 09:34:14 +05:30