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

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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: 3335068f8721 ("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>
This commit is contained in:
Alexandre Ghiti 2023-07-04 14:18:37 +02:00 committed by Palmer Dabbelt
parent f8069826eb
commit c3bcc65d4d
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1 changed files with 6 additions and 1 deletions
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7
arch/riscv/mm/init.c
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@ -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