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References: <20230714165508.94561-1-charlie@rivosinc.com> <20230714165508.94561-4-charlie@rivosinc.com>
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From:   Alexandre Ghiti <alexghiti@rivosinc.com>
Date:   Thu, 20 Jul 2023 09:00:46 +0200
Message-ID: <CAHVXubhUdtiP_G4PwsmQTkKbsQ0PuL-Xjtyowz9iXDeDPeiHFA@mail.gmail.com>
Subject: Re: [PATCH v6 3/4] RISC-V: mm: Update pgtable comment documentation
To:     Charlie Jenkins <charlie@rivosinc.com>
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        conor@kernel.org, paul.walmsley@sifive.com, palmer@rivosinc.com,
        aou@eecs.berkeley.edu, anup@brainfault.org,
        konstantin@linuxfoundation.org, linux-doc@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
        mick@ics.forth.gr, jrtc27@jrtc27.com, rdunlap@infradead.org
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On Fri, Jul 14, 2023 at 6:56=E2=80=AFPM Charlie Jenkins <charlie@rivosinc.c=
om> 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/pg=
table.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 p=
te)
>   * 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 tha=
t
>   * "load and store effective addresses, which are 64bits, must have bits
>   * 63=E2=80=9348 all equal to bit 47, or else a page-fault exception wil=
l occur."
> + * Similarly for SV57, bits 63=E2=80=9357 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