Re: [PATCH v6 11/11] Documentation/virt/kvm/api.rst: Explain rc/rrc delivery

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue, 17 May 2022 16:36:29 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> Let's explain in which situations the rc/rrc will set in struct
> kvm_pv_cmd so it's clear that the struct members should be set to
> 0. rc/rrc are independent of the IOCTL return code.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>

Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  Documentation/virt/kvm/api.rst | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 06d1b717b032..7b0993e4106f 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -5067,6 +5067,14 @@ into ESA mode. This reset is a superset of the initial reset.
>  	__u32 reserved[3];
>    };
>  
> +**Ultravisor return codes**
> +The Ultravisor return (reason) codes are provided by the kernel if a
> +Ultravisor call has been executed to achieve the results expected by
> +the command. Therefore they are independent of the IOCTL return
> +code. If KVM changes `rc`, its value will always be greater than 0
> +hence setting it to 0 before issuing a PV command is advised to be
> +able to detect a change of `rc`.
> +
>  **cmd values:**
>  
>  KVM_PV_ENABLE