Re: [RFC 04/37] KVM: s390: protvirt: Add initial lifecycle handling

[Cornelia Huck <cohuck@redhat.com>]

On Thu, 24 Oct 2019 07:40:26 -0400
Janosch Frank <frankja@linux.ibm.com> wrote:

> +/*
> + * Generic cmd executor for calls that only transport the cpu or guest
> + * handle and the command.
> + */
> +static inline int uv_cmd_nodata(u64 handle, u16 cmd, u32 *ret)
> +{
> +	int rc;
> +	struct uv_cb_nodata uvcb = {
> +		.header.cmd = cmd,
> +		.header.len = sizeof(uvcb),
> +		.handle = handle,
> +	};
> +
> +	WARN(!handle, "No handle provided to Ultravisor call cmd %x\n", cmd);
> +	rc = uv_call(0, (u64)&uvcb);
> +	if (ret)
> +		*ret = *(u32 *)&uvcb.header.rc;
> +	return rc ? -EINVAL : 0;

Why go ahead with doing the uv call if it doesn't have a handle anyway?
Or why warn, if you already know it is going to fail? I assume this can
only happen if you have a logic error in the kvm code?

> +}