On 08/22/2018 05:34 PM, Pierre Morel wrote: > On 22/08/2018 17:11, Christian Borntraeger wrote: >> >> >> On 08/22/2018 01:03 PM, Pierre Morel wrote: >>>> That's interesting. >>>> >>>>> IMHO this quote is quite a half-full half-empty cup one: >>>>> * it mandates the set of usage domains is a subset of the set >>>>> of the control domains, but >>>>> * it speaks of independent controls, namely about the 'usage domain index' >>>>> and the 'control domain index list' and makes the enforcement of the rule >>>>> a job of the administrator (instead of codifying it in the controls). >>>> I'm wondering if a configuration with a usage domain that is not also a >>>> control domain is rejected outright? Anybody tried that? :) >>> >>> Yes, and no it is not. >>> We can use a queue (usage domain) to a AP card for SHA-512 or RSA without >>> having to define the queue as a control domain. >> >> Huh? My HMC allows to add a domain as >> - control only domain >> - control and usage domain. >> >> But I am not able to configure a usage-only domain for my LPAR. That seems to match >> the current code, no? >> > > Yes, it may not be configurable by the HMC but if we start a guest with no control domain it is not a problem to access the hardware through the usage domain. > > I tested this a long time ago, but tested again today to be sure on my LPAR. > > AFAIU adding a control only domain and a control and usage domain > allows say: > control and usage domain 1 > control only domain 2 > > Allow to send a message to domain 2 using queue 1 > > Allow also to send a domain modifying message to domain 1 using queue 1 > > control domain are domain which are controlled So you have changed the code to not automatically make a usage domain a control domain in the bitfield (and you could still use it as a usage domain). Correct? I think this is probably expected. the "usage implies control" seems to be a convention implemented by HMC (lpar) and z/VM but millicode offers the bits to have usage-only domains. As LPAR and z/VM will always enable any usage-domain to also be a control domain we should do the same. > It seems that the HMC enforce the LPARs to have access to their usage domain (AFAIU from Harald)
