On Fri, Apr 12, 2019 at 05:28:17PM +0100, Dave Martin wrote:
> The current error code documentation for KVM_GET_ONE_REG and
> KVM_SET_ONE_REG could be read as implying that all architectures
> implement these error codes, or that KVM guararntees which error
guarantees
> code is returned in a particular situation.
>
> Because this is not really the case, this patch waters down the
> documentation explicitly to remove such guarantees.
>
> EPERM is marked as arm64-specific, since for now arm64 really is
> the only architecture that yields this error code for the
> finalization-required case. Keeping this as a distinct error code
> is useful however for debugging due to the statefulness of the API
> in this instance.
>
> No functional change.
>
> Suggested-by: Andrew Jones <drjones@xxxxxxxxxx>
> Fixes: 395f562f2b4c ("KVM: Document errors for KVM_GET_ONE_REG and KVM_SET_ONE_REG")
> Fixes: 50036ad06b7f ("KVM: arm64/sve: Document KVM API extensions for SVE")
> Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
> ---
> Documentation/virtual/kvm/api.txt | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index b115b23..74c51c7 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1873,8 +1873,10 @@ Parameters: struct kvm_one_reg (in)
> Returns: 0 on success, negative value on failure
> Errors:
> ENOENT: no such register
> - EPERM: register access forbidden for architecture-dependent reasons
> - EINVAL: other errors, such as bad size encoding for a known register
> + EINVAL: invalid register ID, or no such register
> + EPERM: (arm64) register access not allowed before vcpu finalization
> +(These error codes are indicative only: do not rely on a specific error
> +code being returned in a specific situation.)
>
> struct kvm_one_reg {
> __u64 id;
> @@ -2258,10 +2260,12 @@ Architectures: all
> Type: vcpu ioctl
> Parameters: struct kvm_one_reg (in and out)
> Returns: 0 on success, negative value on failure
> -Errors:
> +Errors include:
> ENOENT: no such register
> - EPERM: register access forbidden for architecture-dependent reasons
> - EINVAL: other errors, such as bad size encoding for a known register
> + EINVAL: invalid register ID, or no such register
> + EPERM: (arm64) register access not allowed before vcpu finalization
> +(These error codes are indicative only: do not rely on a specific error
> +code being returned in a specific situation.)
>
> 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
>
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
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