Messages in this thread | | | Subject | Re: [PATCH v7 03/15] s390/zcrypt: driver callback to indicate resource in use | From | Tony Krowiak <> | Date | Mon, 27 Apr 2020 17:36:28 -0400 |
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On 4/24/20 2:23 PM, Halil Pasic wrote: > On Fri, 24 Apr 2020 13:07:38 -0400 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> >> On 4/23/20 11:33 PM, Halil Pasic wrote: >>> On Thu, 16 Apr 2020 11:37:21 +0200 >>> Cornelia Huck <cohuck@redhat.com> wrote: >>> >>>> On Wed, 15 Apr 2020 13:10:10 -0400 >>>> Tony Krowiak <akrowiak@linux.ibm.com> wrote: >>>> >>>>> On 4/14/20 8:58 AM, Cornelia Huck wrote: >>>>>> On Tue, 7 Apr 2020 15:20:03 -0400 >>>>>> Tony Krowiak <akrowiak@linux.ibm.com> wrote: >>>>>>> + >>>>>>> + if (ap_drv->in_use) >>>>>>> + if (ap_drv->in_use(newapm, ap_perms.aqm)) >>>>>> Can we log the offending apm somewhere, preferably with additional info >>>>>> that allows the admin to figure out why an error was returned? >>>>> One of the things on my TODO list is to add logging to the vfio_ap >>>>> module which will track all significant activity within the device >>>>> driver. I plan to do that with a patch or set of patches specifically >>>>> put together for that purpose. Having said that, the best place to >>>>> log this would be in the in_use callback in the vfio_ap device driver >>>>> (see next patch) where the APQNs that are in use can be identified. >>>>> For now, I will log a message to the dmesg log indicating which >>>>> APQNs are in use by the matrix mdev. >>>> Sounds reasonable. My main issue was what an admin was supposed to do >>>> until logging was in place :) >>> Logging may not be the right answer here. Imagine somebody wants to build >>> a nice web-tool for managing this stuff at scale -- e.g. something HMC. I >>> don't think the solution is to let this tool parse the kernel messages >>> and try to relate that to its own transactions. >> I don't believe there is no right or wrong answer here; I simply don't >> see the relevance of discussing a tool in this context. We are talking >> about a sysfs attribute interface here, so - correct me if I'm >> mistaken - our options for notifying the user that a queue is in use are >> limited to the return code from the sysfs interface and logging. I would >> expect that a tool would have to do something similar to the callback >> implemented in the vfio_ap device driver and check the APQNs >> removed against the APQNs assigned to the mdevs to determine which >> is in use. >> > We are talking interface design. The relevance of discussing a tool is > that any userspace tool must come by with whatever interface we come up > now. IMHO thinking about the usage (and the client code) is very helpful > in avoiding broken interface designs. AFAIK this is one of the basic > ideas behind test driven development.
What can a sysfs interface, such as apmask/aqmask, do other than reply with a return code given sysfs attributes that store data can only return a count? I'm sorry, but I still don't see the relevance.
> > Regards, > Halil
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