ACK: [SRU][K][PATCH 1/1] UBUNTU: SAUCE: riscv: mm: Force disable sv57

[Dimitri John Ledkov]

Acked-by: Dimitri John Ledkov <dimitri.ledkov at canonical.com>

On Mon, 10 Oct 2022 at 12:28, Emil Renner Berthing
<emil.renner.berthing at canonical.com> wrote:
>
> From: Alexandre Ghiti <alexandre.ghiti at canonical.com>
>
> BugLink: https://launchpad.net/bugs/1991790
>
> The Kinetic userspace is not yet ready for 5-level page tables. Eg. Go
> programs use too many of the higher bits for pointer tagging.
> So force disable sv57 even on Qemu which advertices support for it.
>
> Signed-off-by: Alexandre Ghiti <alexandre.ghiti at canonical.com>
> Signed-off-by: Emil Renner Berthing <emil.renner.berthing at canonical.com>
> ---
>  arch/riscv/mm/init.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 2c4a64e97aec..18a0c70ed313 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
>                 disable_pgtable_l4();
>         }
>
> +       /* UBUNTU: Force disable sv57 and fallback to sv48 */
> +       if (pgtable_l5_enabled)
> +               disable_pgtable_l5();
> +
>         memset(early_pg_dir, 0, PAGE_SIZE);
>         memset(early_p4d, 0, PAGE_SIZE);
>         memset(early_pud, 0, PAGE_SIZE);
> --
> 2.37.2
>
>
> --
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> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team



-- 
okurrr,

Dimitri