Re: [PATCH v7 26/27] KVM: Document errors for KVM_GET_ONE_REG and KVM_SET_ONE_REG

Andrew Jones
2019-04-03T20:28:05Z

On Fri, Mar 29, 2019 at 01:00:51PM +0000, Dave Martin wrote:
> KVM_GET_ONE_REG and KVM_SET_ONE_REG return some error codes that
> are not documented (but hopefully not surprising either). To give
> an indication of what these may mean, this patch adds brief
> documentation.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> ---
> Documentation/virtual/kvm/api.txt | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 2d4f7ce..cd920dd 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1871,6 +1871,9 @@ Architectures: all
> Type: vcpu ioctl
> Parameters: struct kvm_one_reg (in)
> Returns: 0 on success, negative value on failure
> +Errors:
> +  ENOENT:   no such register
> +  EINVAL:   other errors, such as bad size encoding for a known register
>
> struct kvm_one_reg {
> __u64 id;
> @@ -2192,6 +2195,9 @@ Architectures: all
> Type: vcpu ioctl
> Parameters: struct kvm_one_reg (in and out)
> Returns: 0 on success, negative value on failure
> +Errors:
> +  ENOENT:   no such register
> +  EINVAL:   other errors, such as bad size encoding for a known register
>
> This ioctl allows to receive the value of a single register implemented
> in a vcpu. The register to read is indicated by the "id" field of the
> --
> 2.1.4
>

Are we sure all architectures have these, and only these errors? A quick
grep indicates not. I'm not sure we can document this easily here due to
it addressing all architectures at once. Maybe we could add arch-specific
subsections, but I'm not sure it's worth it.

drew