Re: [PATCH 3/3] RISC-V: KVM: Decouple vector prctl state from VM ISA

[Andy Chiu]

On Wed, Oct 07, 2026 at 01:51:18AM -0700, Samuel Holland wrote:
> The ability to prevent userspace from executing vector instructions was
> provided as a escape hatch for software that was broken by adding vector
> state to the signal context. This was hooked up to KVM so a process that
> could not use V in userspace also could not create a KVM VM with V in
> the ISA.
> 
> Remove this connection as it does not really help with any compatibility
> concerns. A VMM that does not understand V will not include it in the
> virtual machine's ISA.
> 
> Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>

Reviewed-by: Andy Chiu <tchiu@xxxxxxxxxxxxxxx>

> ---
> 
>  arch/riscv/kvm/isa.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/arch/riscv/kvm/isa.c b/arch/riscv/kvm/isa.c
> index 971f44655100a..447c778bf850e 100644
> --- a/arch/riscv/kvm/isa.c
> +++ b/arch/riscv/kvm/isa.c
> @@ -9,7 +9,6 @@
>  #include <linux/nospec.h>
>  #include <linux/pgtable.h>
>  #include <asm/kvm_isa.h>
> -#include <asm/vector.h>
>  
>  #define KVM_ISA_EXT_ARR(ext)		\
>  [KVM_RISCV_ISA_EXT_##ext] = RISCV_ISA_EXT_##ext
> @@ -159,8 +158,6 @@ bool kvm_riscv_isa_enable_allowed(unsigned long ext)
>  		 * Guest OS can use Svadu only when host OS enable Svadu.
>  		 */
>  		return arch_has_hw_pte_young();
> -	case KVM_RISCV_ISA_EXT_V:
> -		return riscv_v_vstate_ctrl_user_allowed();
>  	default:
>  		break;
>  	}
> -- 
> 2.52.0
>