From 8486218eb60d6ec324e8ae4286547bf857b9dd83 Mon Sep 17 00:00:00 2001 From: Alexandre Ghiti Date: Tue, 4 Jul 2023 14:18:37 +0200 Subject: [PATCH] riscv: Start of DRAM should at least be aligned on PMD size for the direct mapping commit c3bcc65d4d2e8292c435322cbc34c318d06b8b6c upstream. 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 Reported-by: Song Shuai Fixes: 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear mapping") Tested-by: Song Shuai Link: https://lore.kernel.org/r/20230704121837.248976-1-alexghiti@rivosinc.com Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- arch/riscv/mm/init.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 93e7bb9f67fd..b3495bbd0f7d 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -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