[PATCH v2 3/3] RISC-V: KVM: Reset the SBI extension when disable it

[Anup Patel]

On Mon, Jul 6, 2026 at 7:42 AM Inochi Amaoto <inochiama at gmail.com> wrote:
>
> The SBI extension validation callback can only fix the parameter if
> the extension is enabled. However, if the extension is disabled after
> modifty some parameters, the state of the extension is still broken.
>
> Reset the extension when the extenion is disabled so it can have

s/extenion/extension/

> a clear context.
>
> Signed-off-by: Inochi Amaoto <inochiama at gmail.com>
> ---
>  arch/riscv/kvm/vcpu_sbi.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> index b737e9a7a12a..3eb7b7c57059 100644
> --- a/arch/riscv/kvm/vcpu_sbi.c
> +++ b/arch/riscv/kvm/vcpu_sbi.c
> @@ -221,6 +221,7 @@ static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu,
>  {
>         struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
>         const struct kvm_riscv_sbi_extension_entry *sext;
> +       const struct kvm_vcpu_sbi_extension *ext;
>
>         if (reg_val != 1 && reg_val != 0)
>                 return -EINVAL;
> @@ -229,6 +230,15 @@ static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu,
>         if (!sext || scontext->ext_status[sext->ext_idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE)
>                 return -ENOENT;
>
> +       ext = sext->ext_ptr;
> +
> +       if (!reg_val && scontext->ext_status[sext->ext_idx] == KVM_RISCV_SBI_EXT_STATUS_ENABLED) {
> +               if (ext->reset) {
> +                       ext->reset(vcpu);
> +                       vcpu->arch.csr_dirty = true;

Let's not blindly set "csr_dirty" when any SBI extension is disabled,
instead we should set "csr_dirtry" in kvm_sbi_ext_fwft_reset() (just
like we do in kvm_sbi_ext_fwft_set_reg()).

> +               }
> +       }
> +
>         scontext->ext_status[sext->ext_idx] = (reg_val) ?
>                         KVM_RISCV_SBI_EXT_STATUS_ENABLED :
>                         KVM_RISCV_SBI_EXT_STATUS_DISABLED;
> --
> 2.55.0
>

Regards,
Anup