[PATCH] lib: sbi: sbi_mpxy_set_shmem adds parameter check

[Anup Patel]

On Wed, Mar 19, 2025 at 6:07 PM Xiang W <wxjstz at 126.com> wrote:
>
> Shared memory needs to be accessed in M-Mode, and the high address of
> physical memory should be 0

The patch subject and description needs to be improved but I will take care
of it at the time of merging this patch.

>
> Signed-off-by: Xiang W <wxjstz at 126.com>
> ---
>  lib/sbi/sbi_mpxy.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/lib/sbi/sbi_mpxy.c b/lib/sbi/sbi_mpxy.c
> index c5d9d1bb..7d4d26ab 100644
> --- a/lib/sbi/sbi_mpxy.c
> +++ b/lib/sbi/sbi_mpxy.c
> @@ -287,6 +287,20 @@ int sbi_mpxy_set_shmem(unsigned long shmem_phys_lo,
>         if (shmem_phys_lo & ~PAGE_MASK)
>                 return SBI_ERR_INVALID_PARAM;
>
> +       /*
> +       * On RV32, the M-mode can only access the first 4GB of
> +       * the physical address space because M-mode does not have
> +       * MMU to access full 34-bit physical address space.
> +       * So fail if the upper 32 bits of the physical address
> +       * is non-zero on RV32.
> +       *
> +       * On RV64, kernel sets upper 64bit address part to zero.
> +       * So fail if the upper 64bit of the physical address
> +       * is non-zero on RV64.
> +       */
> +       if (shmem_phys_hi)
> +               return SBI_ERR_INVALID_PARAM;

The error code should be SBI_ERR_INVALID_ADDRESS to align
with the SBI spec. I will address this at the time of merging this
patch.

> +
>         if (!sbi_domain_check_addr_range(sbi_domain_thishart_ptr(),
>                                 SHMEM_PHYS_ADDR(shmem_phys_hi, shmem_phys_lo),
>                                 mpxy_shmem_size, PRV_S,
> --
> 2.47.2
>

Reviewed-by: Anup Patel <anup at brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup