Unverified Commit c3bcc65d authored Jul 04, 2023 by Alexandre Ghiti Committed by Palmer Dabbelt Aug 04, 2023

riscv: Start of DRAM should at least be aligned on PMD size for the direct mapping



So that we do not end up mapping the whole linear mapping using 4K
pages, which is slow at boot time, and also very likely at runtime.

So make sure we align the start of DRAM on a PMD boundary.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reported-by: Song Shuai <suagrfillet@gmail.com>
Fixes: 3335068f ("riscv: Use PUD/P4D/PGD pages for the linear mapping")
Tested-by: Song Shuai <suagrfillet@gmail.com>
Link: https://lore.kernel.org/r/20230704121837.248976-1-alexghiti@rivosinc.com


Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

parent f8069826

arch/riscv/mm/init.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -214,8 +214,13 @@ static void __init setup_bootmem(void)
		memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);

		phys_ram_end = memblock_end_of_DRAM();

		/*
		* Make sure we align the start of the memory on a PMD boundary so that
		* at worst, we map the linear mapping with PMD mappings.
		*/
		if (!IS_ENABLED(CONFIG_XIP_KERNEL))
		phys_ram_base = memblock_start_of_DRAM();
		phys_ram_base = memblock_start_of_DRAM() & PMD_MASK;

		/*
		* In 64-bit, any use of __va/__pa before this point is wrong as we