On Wed, Feb 01, 2023 at 03:12:40PM -0800, Atish Patra wrote:
> Currently the probe function just checks if an SBI extension is
> registered or not. However, the extension may not want to advertise
> itself depending on some other condition.
> An additional extension specific probe function will allow
> extensions to decide if they want to be advertised to the caller or
> not. Any extension that does not require additional dependency checks
> can avoid implementing this function.
>
> Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
> Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
> ---
> arch/riscv/include/asm/kvm_vcpu_sbi.h | 3 +++
> arch/riscv/kvm/vcpu_sbi_base.c | 13 +++++++++++--
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> index f79478a..45ba341 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -29,6 +29,9 @@ struct kvm_vcpu_sbi_extension {
> int (*handler)(struct kvm_vcpu *vcpu, struct kvm_run *run,
> unsigned long *out_val, struct kvm_cpu_trap *utrap,
> bool *exit);
> +
> + /* Extension specific probe function */
> + unsigned long (*probe)(struct kvm_vcpu *vcpu);
> };
>
> void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);
> diff --git a/arch/riscv/kvm/vcpu_sbi_base.c b/arch/riscv/kvm/vcpu_sbi_base.c
> index 5d65c63..846d518 100644
> --- a/arch/riscv/kvm/vcpu_sbi_base.c
> +++ b/arch/riscv/kvm/vcpu_sbi_base.c
> @@ -19,6 +19,7 @@ static int kvm_sbi_ext_base_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> {
> int ret = 0;
> struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
> + const struct kvm_vcpu_sbi_extension *sbi_ext;
>
> switch (cp->a6) {
> case SBI_EXT_BASE_GET_SPEC_VERSION:
> @@ -43,8 +44,16 @@ static int kvm_sbi_ext_base_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> */
> kvm_riscv_vcpu_sbi_forward(vcpu, run);
> *exit = true;
> - } else
> - *out_val = kvm_vcpu_sbi_find_ext(cp->a0) ? 1 : 0;
> + } else {
> + sbi_ext = kvm_vcpu_sbi_find_ext(cp->a0);
> + if (sbi_ext) {
> + if (sbi_ext->probe)
> + *out_val = sbi_ext->probe(vcpu);
> + else
> + *out_val = 1;
> + } else
> + *out_val = 0;
Conor points out elsewhere that we need {} on both arms if one arm needs
it. We actually don't need {} on either arm, though, or even the if, if
we rewrite as
*out_val = sbi_ext && sbi_ext->probe ? sbi_ext->probe(vcpu) : !!sbi_ext;
Thanks,
drew
> + }
> break;
> case SBI_EXT_BASE_GET_MVENDORID:
> *out_val = vcpu->arch.mvendorid;
> --
> 2.25.1
>
