Subject: [PATCH v5 4/7] support user space to query RAS extension feature

From: [email-masked] (Jonathan Cameron)
Date: Tue, 22 Aug 2017 08:56:44 +0100

On Fri, 18 Aug 2017 22:11:54 +0800
Dongjiu Geng <[email-masked]> wrote:

> In armv8.2 RAS extension, it adds virtual SError exception
> syndrome registeri(VSESR_EL2), user space will specify that
> value. so user space will check whether CPU feature has RAS
> extension. if has, it will specify the virtual SError syndrome
> value. Otherwise, it will not set. This patch adds this support

In the armv8.2 RAS extension, a virtual SError exception syndrome
registeri(VSESR_EL) is added.  This value may be specified from userspace.
Userspace will want to check if the CPU has the RAS extension.
If it has, it wil specify the virtual SError syndrome value, otherwise
it will not be set.  This patch adds support for querying the availability
of this extension.

Code is fine.
> 
> Signed-off-by: Dongjiu Geng <[email-masked]>
> ---
>  arch/arm64/kvm/reset.c   | 3 +++
>  include/uapi/linux/kvm.h | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index 3256b9228e75..b7313ee028e9 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -77,6 +77,9 @@ int kvm_arch_dev_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ARM_PMU_V3:
>  		r = kvm_arm_support_pmu_v3();
>  		break;
> +	case KVM_CAP_ARM_RAS_EXTENSION:
> +		r = cpus_have_const_cap(ARM64_HAS_RAS_EXTN);
> +		break;
>  	case KVM_CAP_SET_GUEST_DEBUG:
>  	case KVM_CAP_VCPU_ATTRIBUTES:
>  		r = 1;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 6cd63c18708a..5a2a338cae57 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -929,6 +929,7 @@ struct kvm_ppc_resize_hpt {
>  #define KVM_CAP_PPC_SMT_POSSIBLE 147
>  #define KVM_CAP_HYPERV_SYNIC2 148
>  #define KVM_CAP_HYPERV_VP_INDEX 149
> +#define KVM_CAP_ARM_RAS_EXTENSION 150
>  
>  #ifdef KVM_CAP_IRQ_ROUTING
>