On 16.10.2023 15:00, Roger Pau Monné wrote:
> On Mon, Oct 16, 2023 at 02:35:44PM +0200, Jan Beulich wrote:
>> On 06.10.2023 15:00, Roger Pau Monne wrote:
>>> --- a/xen/common/domain.c
>>> +++ b/xen/common/domain.c
>>> @@ -1998,6 +1998,10 @@ long common_vcpu_op(int cmd, struct vcpu *v,
>>> XEN_GUEST_HANDLE_PARAM(void) arg)
>>> {
>>> struct vcpu_register_runstate_memory_area area;
>>>
>>> + rc = -ENOSYS;
>>> + if ( 0 /* TODO: Dom's XENFEAT_runstate_phys_area setting */ )
>>> + break;
>>> +
>>> rc = -EFAULT;
>>> if ( copy_from_guest(&area.addr.p, arg, 1) )
>>> break;
>>
>> ENOSYS is not correct here. EPERM, EACCES, or EOPNOTSUPP would all be more
>> correct.
>
> I don't think so, common_vcpu_op() default case does return -ENOSYS,
> and the point of this path is to mimic the behavior of an hypervisor
> that doesn't have the hypercalls implemented, hence -ENOSYS is the
> correct behavior.
Besides that other ENOSYS being wrong too, I question such "mimic-ing".
Imo error codes should be the best representation of the real reason,
not be arbitrarily "made up".
Jan
