Re: [PATCH v6 3/4] RISC-V: mm: Update pgtable comment documentation

Alexandre Ghiti
2023-07-20T07:01:15Z

On Fri, Jul 14, 2023 at 6:56 PM Charlie Jenkins <charlie@rivosinc.com> wrote:
>
> sv57 is supported in the kernel so pgtable.h should reflect that.
>
> Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
> arch/riscv/include/asm/pgtable.h | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index e13f5872bfe9..28660bab754c 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -840,14 +840,16 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32.
> * Note that PGDIR_SIZE must evenly divide TASK_SIZE.
> * Task size is:
> - * - 0x9fc00000 (~2.5GB) for RV32.
> - * - 0x4000000000 ( 256GB) for RV64 using SV39 mmu
> - * - 0x800000000000 ( 128TB) for RV64 using SV48 mmu
> + * - 0x9fc00000 (~2.5GB) for RV32.
> + * - 0x4000000000 ( 256GB) for RV64 using SV39 mmu
> + * - 0x800000000000 ( 128TB) for RV64 using SV48 mmu
> + * - 0x100000000000000 ( 64PB) for RV64 using SV57 mmu
> *
> * Note that PGDIR_SIZE must evenly divide TASK_SIZE since "RISC-V
> * Instruction Set Manual Volume II: Privileged Architecture" states that
> * "load and store effective addresses, which are 64bits, must have bits
> * 63–48 all equal to bit 47, or else a page-fault exception will occur."
> + * Similarly for SV57, bits 63–57 must be equal to bit 56.
> */
> #ifdef CONFIG_64BIT
> #define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2)
> --
> 2.41.0
>

You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex