RE: [RFC 11/12] keys/mktme: Add a new key service type for memory encryption keys

["Huang, Kai" <kai.huang@intel.com>]

> > On Sun, Sep 09, 2018 at 08:29:29PM -0700, Huang, Kai wrote:
> > > > + */
> > > > +static int mktme_build_cpumask(void) {
> > > > +	int online_cpu, mktme_cpu;
> > > > +	int online_pkgid, mktme_pkgid = -1;
> > > > +
> > > > +	if (!zalloc_cpumask_var(&mktme_cpumask, GFP_KERNEL))
> > > > +		return -ENOMEM;
> > > > +
> > > > +	for_each_online_cpu(online_cpu) {
> > > > +		online_pkgid = topology_physical_package_id(online_cpu);
> > > > +
> > > > +		for_each_cpu(mktme_cpu, mktme_cpumask) {
> > > > +			mktme_pkgid =
> > > > topology_physical_package_id(mktme_cpu);
> > > > +			if (mktme_pkgid == online_pkgid)
> > > > +				break;
> > > > +		}
> > > > +		if (mktme_pkgid != online_pkgid)
> > > > +			cpumask_set_cpu(online_cpu, mktme_cpumask);
> > > > +	}
> > >
> > > Could we use 'for_each_online_node', 'cpumask_first/next', etc to
> > > simplify the
> > logic?
> >
> > Kai,
> >
> > I tried to simplify it and came up with code that looked like this:
> >
> > 	int lead_cpu, node;
> > 	for_each_online_node(node) {
> > 		lead_cpu = cpumask_first(cpumask_of_node(node));
> > 		if (lead_cpu < nr_cpu_ids)
> > 			cpumask_set_cpu(lead_cpu, mktme_cpumask_NEW);
> > 	}
> > When I test it on an SNC (Sub Numa Cluster) system it gives me too many
> CPU's.
> > I get a CPU per Node (just like i asked for;) instead of per Socket.
> > It has 2 sockets and 4 NUMA nodes.
> >
> > I kind of remember this when I originally coded it, hence the bottoms
> > up approach using topology_physical_package_id()
> >
> > Any ideas?
> 
> Hmm.. I forgot the SNC case, sorry :(
> 
> So in case of SNC, is PCONFIG per-package, or per-node? I am not quite sure
> about this.

I have confirmed internally that PCONFIG is per-package even in SNC.

Thanks,
-Kai
> 
> If PCONFIG is per-package, I don't have better idea than your original one. :)
> 
> Thanks,
> -Kai
> >
> > Alison
> >