[PATCH v2 16/17] KVM: arm64: Allow userspace to request KVM_ARM_VCPU_EL2*

[Ganapatrao Kulkarni]

Hi Marc,

On 08-04-2025 04:22 pm, Marc Zyngier wrote:
> Since we're (almost) feature complete, let's allow userspace to
> request KVM_ARM_VCPU_EL2* by bumping KVM_VCPU_MAX_FEATURES up.
> 
> We also now advertise the features to userspace with new capabilities.
> 
> It's going to be great...
> 
> Reviewed-by: Oliver Upton <oliver.upton at linux.dev>
> Reviewed-by: Joey Gouly <joey.gouly at arm.com>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>   arch/arm64/include/asm/kvm_host.h | 2 +-
>   arch/arm64/kvm/arm.c              | 6 ++++++
>   include/uapi/linux/kvm.h          | 2 ++
>   3 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index b2c535036a06b..79e175a16d356 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -39,7 +39,7 @@
>   
>   #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
>   
> -#define KVM_VCPU_MAX_FEATURES 7
> +#define KVM_VCPU_MAX_FEATURES 9
>   #define KVM_VCPU_VALID_FEATURES	(BIT(KVM_VCPU_MAX_FEATURES) - 1)
>   
>   #define KVM_REQ_SLEEP \
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 5287435873609..b021ce1e42c5c 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -368,6 +368,12 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>   	case KVM_CAP_ARM_EL1_32BIT:
>   		r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);
>   		break;
> +	case KVM_CAP_ARM_EL2:
> +		r = cpus_have_final_cap(ARM64_HAS_NESTED_VIRT);
> +		break;
> +	case KVM_CAP_ARM_EL2_E2H0:
> +		r = cpus_have_final_cap(ARM64_HAS_HCR_NV1);
> +		break;
>   	case KVM_CAP_GUEST_DEBUG_HW_BPS:
>   		r = get_num_brps();
>   		break;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index b6ae8ad8934b5..c9d4a908976e8 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -930,6 +930,8 @@ struct kvm_enable_cap {
>   #define KVM_CAP_X86_APIC_BUS_CYCLES_NS 237
>   #define KVM_CAP_X86_GUEST_MODE 238
>   #define KVM_CAP_ARM_WRITABLE_IMP_ID_REGS 239
> +#define KVM_CAP_ARM_EL2 240
> +#define KVM_CAP_ARM_EL2_E2H0 241
>   
>   struct kvm_irq_routing_irqchip {
>   	__u32 irqchip;

After applying PATCH 16/17 (this patch) and PATCH 2/17 on top of
6.15-rc1, I could boot L1 then L2.
Glad to see that the majority of NV patches are merged upstream!!.

Please feel free to add,
Reviewed-by: Ganapatrao Kulkarni <gankulkarni at os.amperecomputing.com>

-- 
Thanks,
Ganapat/GK