Re: [Xen-devel] Xen Dom0 boot failure on platform that supports ARM GICv4

[Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>]

> -----Original Message-----
> From: Julien Grall [mailto:julien.grall@xxxxxxx]
> Sent: 04 September 2018 12:22
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>;
> xen-devel@xxxxxxxxxxxxx
> Cc: sstabellini@xxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; Andre
> Przywara <andre.przywara@xxxxxxx>
> Subject: Re: Xen Dom0 boot failure on platform that supports ARM GICv4

[...] 
 
> >> I may have an idea what is happening. As we populate more regions than
> >> necessary, it is possible that Linux is trying to access them. Would it
> >> be possible to add some debug in the Linux function gic_iterate_rdists
> >> to know what the kernel is trying to read?
> >
> > Ok, enabled earlycon for Dom0. Please find the log below,
> 
> Thank you for the log. I now have an idea what's is going wrong. The function
> gic_iterate_rdists can be used to go through all the re-distributor (for 
> instance
> to check whether vLPIs is available).
> 
> Because some of the regions are empty (i.e not emulated), you end up to trap.
> Your
> patch solves the problem by making regions not empty in the case of GICv4. But
> I
> think this can also happen when the number of vCPUs for Dom0 get restricted.

Yes, that’s right. I didn’t consider that.

> Can you have a try at the patch below? I haven't tested on ACPI.
> 
> If that works for you, I will add the DT case, clean it up and send it.

Thanks for the patch. It works. Please CC me when you send the revised one,
I can retest and provide T-by.

Cheers,
Shameer

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