Subject: [PATCH v2 04/10] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

From: [email-masked] (Christoffer Dall)
Date: Mon, 13 Apr 2015 14:12:31 +0200

On Tue, Mar 31, 2015 at 04:08:02PM +0100, Alex Benn?e wrote:
> This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
> ioctl. Currently any operation flag will return EINVAL. Actual
> functionality will be added with further patches.
> 
> Signed-off-by: Alex Benn?e <[email-masked]>.
> 
> ---
> v2
>   - simplified form of the ioctl (stuff will go into setup_debug)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index b112efc..06c5064 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2604,7 +2604,7 @@ handled.
>  4.87 KVM_SET_GUEST_DEBUG
>  
>  Capability: KVM_CAP_SET_GUEST_DEBUG
> -Architectures: x86, s390, ppc
> +Architectures: x86, s390, ppc, arm64
>  Type: vcpu ioctl
>  Parameters: struct kvm_guest_debug (in)
>  Returns: 0 on success; -1 on error
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 5560f74..445933d 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -183,6 +183,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_ARM_PSCI:
>  	case KVM_CAP_ARM_PSCI_0_2:
>  	case KVM_CAP_READONLY_MEM:
> +	case KVM_CAP_SET_GUEST_DEBUG:
>  		r = 1;
>  		break;

shouldn't you wait with advertising this capability until you've
implemented support for it?

Thanks,
-Christoffer