Re: [Xen-devel] [PATCH v7 1/6] x86/domain: remove the 'oos_off' flag

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.09.2019 15:06, Paul Durrant wrote:
>> From: Jan Beulich <jbeulich@xxxxxxxx>
>> Sent: 02 September 2019 13:34
>>
>> On 30.08.2019 10:29, Paul Durrant wrote:
>>> --- a/xen/common/domain.c
>>> +++ b/xen/common/domain.c
>>> @@ -313,11 +313,19 @@ static int sanitise_domain_config(struct 
>>> xen_domctl_createdomain *config)
>>>          return -EINVAL;
>>>      }
>>>
>>> -    if ( !(config->flags & XEN_DOMCTL_CDF_hvm_guest) &&
>>> -         (config->flags & XEN_DOMCTL_CDF_hap) )
>>> +    if ( !(config->flags & XEN_DOMCTL_CDF_hvm_guest) )
>>>      {
>>> -        dprintk(XENLOG_INFO, "HAP requested for non-HVM guest\n");
>>> -        return -EINVAL;
>>> +        if ( config->flags & XEN_DOMCTL_CDF_hap )
>>> +        {
>>> +            dprintk(XENLOG_INFO, "HAP requested for non-HVM guest\n");
>>> +            return -EINVAL;
>>> +        }
>>> +
>>> +        /*
>>> +         * It is only meaningful for XEN_DOMCTL_CDF_oos_off to be clear
>>> +         * for HVM guests.
>>> +         */
>>> +        config->flags |= XEN_DOMCTL_CDF_oos_off;
>>
>> ... I wonder whether this last part wouldn't better belong into
>> x86's arch_sanitise_domain_config(). Arm, to the contrary, should
>> force/require the bit to be uniformly off.
>>
> 
> I'm sure I had a reason for doing it like this but it's sufficiently long
> ago now that I've forgotten what it was*. Would it be ok to take the code
> as-is and I'll investigate whether this can be tidied up?

Well, with this pending question I'm less inclined to stop waiting for
the outstanding acks.

> [ * I suspect it was concern over breaking existing tool-stacks by
> requiring them to set a flag that previously they did not need to, but
> I'm not sure that was the only reason ]

Seems rather unlikely to me, as there wouldn't be any difference (from
tool stack perspective) if the adjustment was done by per-arch code.

Jan

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