[PATCH 5/9] RISC-V: KVM: Provide UAPI for Zicboz block size

[Anup Patel]

On Thu, Oct 27, 2022 at 6:34 PM Andrew Jones <ajones at ventanamicro.com> wrote:
>
> We're about to allow guests to use the Zicboz extension. KVM
> userspace needs to know the cache block size in order to
> properly advertise it to the guest. Provide a virtual config
> register for userspace to get it with the GET_ONE_REG API, but
> setting it cannot be supported, so disallow SET_ONE_REG.
>
> Signed-off-by: Andrew Jones <ajones at ventanamicro.com>

Looks good to me.

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

Regards,
Anup

> ---
>  arch/riscv/include/uapi/asm/kvm.h | 1 +
>  arch/riscv/kvm/vcpu.c             | 7 +++++++
>  2 files changed, 8 insertions(+)
>
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index 8985ff234c01..4bbf55cb2b70 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -49,6 +49,7 @@ struct kvm_sregs {
>  struct kvm_riscv_config {
>         unsigned long isa;
>         unsigned long zicbom_block_size;
> +       unsigned long zicboz_block_size;
>  };
>
>  /* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 71ebbc4821f0..18a739070b51 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -270,6 +270,11 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
>                         return -EINVAL;
>                 reg_val = riscv_cbom_block_size;
>                 break;
> +       case KVM_REG_RISCV_CONFIG_REG(zicboz_block_size):
> +               if (!riscv_isa_extension_available(vcpu->arch.isa, ZICBOZ))
> +                       return -EINVAL;
> +               reg_val = riscv_cboz_block_size;
> +               break;
>         default:
>                 return -EINVAL;
>         }
> @@ -329,6 +334,8 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
>                 break;
>         case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
>                 return -EOPNOTSUPP;
> +       case KVM_REG_RISCV_CONFIG_REG(zicboz_block_size):
> +               return -EOPNOTSUPP;
>         default:
>                 return -EINVAL;
>         }
> --
> 2.37.3
>
>
> --
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