Re: [PATCH v1 1/2] xen/riscv: skip disabled CPU nodes when probing ISA extensions

[Baptiste Le Duc <baptiste.le-duc@xxxxxxxxxx>]

On 11/9/26 3:40 PM, Oleksii Kurochko wrote:
> On 11/9/26 2:23 PM, Baptiste Le Duc wrote:
> > > riscv_fill_hwcap_from_isa_string() intersects the riscv,isa of every CPU
> > > node under /cpus, including the ones with status = "disabled". Such a
> > > hart is never used by Xen, yet it can still remove extensions from the
> > > host ISA: e.g. a disabled hart without the H extension makes Xen panic
> > > with "Xen requires extension: h", even though every hart Xen runs on
> > > implements it.
> > >
> > > Skip CPU nodes which aren't available.
> > has_isa_extensions_property() still walks the disabled nodes, so the two
> > loops over /cpus now disagree on which harts count. Rather than adding
> > the check loop by loop, can we filter them in one place, e.g. with a
> > dt_for_each_available_child_node() iterator, so no /cpus walk sees a 
> > disabled
> > hart?
> I missed updating has_isa_extensions_property() because I had Cristian 
> Andrei's patch in mind, which adds support for the riscv,isa-extensions 
> property (the patch isn't published to ML). This function will be 
> completely dropped as part of that work.
Oh okay I didn't know that.
> So, until that patch is published, it would probably be better to add an 
> additional check to has_isa_extensions_property().
> Regarding the question of whether to use 
> dt_for_each_available_child_node(), I don't see many use cases for it 
> beyond this particular one. There are also plenty of cases where it's 
> perfectly fine for a node to be disabled and still parsed, so I'm not 
> entirely convinced that we need this change now.
> Let's just add an explicit check to has_isa_extensions_property() for 
> now. Are you okay with that or still think it'll be better to introduce 
> dt_for_each_available_child_node() specifically for this case?
Fine with me. If more cases show up later, we can introduce
dt_for_each_available_child_node() then.
> ~ Oleksii