Re: Lockdep show 6.6-rc regression in Xen HVM CPU hotplug

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Wed, 2023-10-25 at 09:19 +0200, Juergen Gross wrote:
> On 24.10.23 15:45, David Woodhouse wrote:
> > On Tue, 2023-10-24 at 14:08 +0200, Juergen Gross wrote:
> > > 
> > > > I can probably change xen_send_IPI_one() to not need 
> > > > irq_get_chip_data().
> > > 
> > > David, could you test the attached patch, please? Build tested only.
> > 
> > No longer whines when offlining CPU1.
> > 
> > Still triple-faults when bringing it back online. Or if I remove the
> > lockdep_assert_irqs_disabled() from load_current_idt(), gives the same
> > warnings as before, all on the same theme about IRQs being enabled when
> > they shouldn't be.
> 
> I think this is a false positive. No idea (again) why it would trigger only
> with my patch applied.
> 
> The problem seems to be that lockdep_assert_irqs_disabled() doesn't know
> about the "cli" at the very beginning of trampoline_start().

FWIW this is fixed by
https://lore.kernel.org/lkml/a079bba5a0e47d6534b307553fc3772d26ce911b.camel@xxxxxxxxxxxxx/

And would be a whole lot easier to debug if something like this happens
again, after
https://lore.kernel.org/lkml/635fa006e8f3816b4a36b964d6281f0d8efa789b.camel@xxxxxxxxxxxxx/

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