[PATCH] lib: sbi: Preserve vl and vtype during domain switches

[Anup Patel]

On Fri, Oct 23, 2026 at 5:11 AM whensun
<theodoruswensanfebruanto025 at gmail.com> wrote:
>
> Save vl and vtype as part of the Vector domain context.
>
> Restore both CSRs using vsetvl after restoring the Vector register
> file. Restore vstart after vsetvl because Vector configuration
> instructions reset vstart.
>
> Link: https://github.com/riscv-software-src/opensbi/issues/434
> Signed-off-by: whensun <theodoruswensanfebruanto025 at gmail.com>

Expand your other series "Preserve more S/HS architectural state
across domain switches" to include this patch as well.

Better to call that series "Preserve more architectural state across
domain switches".

> ---
>  include/sbi/sbi_vector.h |  2 ++
>  lib/sbi/sbi_vector.c     | 11 +++++++++++
>  2 files changed, 13 insertions(+)
>
> diff --git a/include/sbi/sbi_vector.h b/include/sbi/sbi_vector.h
> index c14f3174..480f9ac3 100644
> --- a/include/sbi/sbi_vector.h
> +++ b/include/sbi/sbi_vector.h
> @@ -15,6 +15,8 @@
>  struct sbi_vector_context {
>         unsigned long vcsr;
>         unsigned long vstart;
> +       unsigned long vl;
> +       unsigned long vtype;
>
>         /* size depends on VLEN */
>         uint8_t vregs[];
> diff --git a/lib/sbi/sbi_vector.c b/lib/sbi/sbi_vector.c
> index 1f9e01cf..53c2e5a7 100644
> --- a/lib/sbi/sbi_vector.c
> +++ b/lib/sbi/sbi_vector.c
> @@ -33,6 +33,8 @@ void sbi_vector_save(struct sbi_vector_context *dst)
>         /* Step 2: Save CSRs */
>         dst->vcsr = csr_read(vcsr);
>         dst->vstart = csr_read(vstart);
> +       dst->vl = csr_read(vl);
> +       dst->vtype = csr_read(vtype);
>
>         /* Step 3: Save vector registers */
>  #define SAVE_VREG(i)                                                   \
> @@ -86,6 +88,15 @@ void sbi_vector_restore(const struct sbi_vector_context *src)
>
>         /* Step 3: Restore CSR's last */
>         /* Restore CSRs first */
> +       asm volatile(
> +               ".option push\n\t"
> +               ".option arch, +v\n\t"
> +               "vsetvl zero, %0, %1\n\t"
> +               ".option pop\n\t"
> +               :
> +               : "r"(src->vl), "r"(src->vtype)
> +               : "memory");
> +
>         csr_write(vcsr,   src->vcsr);
>         csr_write(vstart, src->vstart);
>
> --
> 2.43.0
>
>
> --
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> opensbi at lists.infradead.org
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Regards,
Anup