Messages in this thread | | | Date | Mon, 8 Nov 2021 12:20:26 -0500 | Subject | Re: [PATCH] x86/smp: Factor out parts of native_smp_prepare_cpus() | From | Boris Ostrovsky <> |
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On 11/8/21 10:11 AM, Peter Zijlstra wrote: > On Tue, Nov 02, 2021 at 07:36:36PM -0400, Boris Ostrovsky wrote: >> Commit 66558b730f25 ("sched: Add cluster scheduler level for x86") >> introduced cpu_l2c_shared_map mask which is expected to be initialized >> by smp_op.smp_prepare_cpus(). That commit only updated >> native_smp_prepare_cpus() version but not xen_pv_smp_prepare_cpus(). >> As result Xen PV guests crash in set_cpu_sibling_map(). >> >> While the new mask can be allocated in xen_pv_smp_prepare_cpus() one can >> see that both versions of smp_prepare_cpus ops share a number of common >> operations that can be factored out. So do that instead. >> >> Fixes: 66558b730f25 ("sched: Add cluster scheduler level for x86") >> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Thanks! I'll go stick that somewhere /urgent (I've had another report on > that here: > > https://lkml.kernel.org/r/20211105074139.GE174703@worktop.programming.kicks-ass.net > )
Thank you. (I don't see this message btw)
> > But looking at those functions; there seems to be more spurious > differences. For example, the whole sched_topology thing.
I did look at that and thought this should be benign given that Xen PV is not really topology-aware. I didn't see anything that would be a cause for concern but perhaps you can point me to things I missed.
> > Should we re-architect this whole smp_prepare_cpus() thing instead? Have > a common function and a guest function? HyperV for instance seems to > call native_smp_prepare_cpus() and then does something extra (as does > xen_hvm).
Something like
void smp_prepare_cpus()
{
// Code that this patch moved to smp_prepare_cpus_common();
smp_ops.smp_prepare_cpus(); // Including baremetal
}
?
XenHVM and hyperV will need to call native smp_op too. Not sure this will be prettier than what it is now?
-boris
-boris
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