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

Christoffer Dall
2015-04-13T12:04:41Z

On Tue, Mar 31, 2015 at 04:08:02PM +0100, Alex Bennée 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 Bennée <alex.bennee@linaro.org>.
>
> ---
> 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