Re: [PATCH] genirq/irqdomain: Don't call ops->select for DOMAIN_BUS_ANY tokens

[Marc Zyngier]

On 2024-02-25 16:19, Thomas Gleixner wrote:
> On Tue, Feb 20 2024 at 11:47, Marc Zyngier wrote:
> > Users of the IRQCHIP_PLATFORM_DRIVER_{BEGIN,END} helpers rely
> > on a fwspec containing only the fwnode (and crucially a number
> > of parameters set to 0) together with a DOMAIN_BUS_ANY token
> > to check whether a parent irqchip has probed and registered
> > a domain.
> >
> > Since de1ff306dcf4 ("genirq/irqdomain: Remove the param count
> > restriction from select()"), we call ops->select unconditionally,
> > meaning that irqchips implementing select now need to handle
> > ANY as a match.
> >
> > Instead of adding more esoteric checks to the individual drivers,
> > add that condition to irq_find_matching_fwspec(), and let it
> > handle the corner case, as per the comment in the function.
> >
> > This restores the functionnality of the above helpers.
> >
> > Reported-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Tested-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Reported-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > Fixes: de1ff306dcf4 ("genirq/irqdomain: Remove the param count 
> > restriction from select()")
> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> > Link: 
> > https://lore.kernel.org/r/20240219-gic-fix-child-domain-v1-1-09f8fd2d9a8f@xxxxxxxxxx
>
> Bah. That breaks x86 because it uses DOMAIN_BUS_ANY to find the MSI
> parent for a fwspec (IOAPIC and HPET) which gets either picked up by 
> the
> interrupt remapping or by the root vector domain.
>
> Fix below.
>
> Thanks,
>
>         tglx
> ---
> Subject: x86/apic/msi: Use DOMAIN_BUS_GENERIC_MSI for HPET/IO-APIC 
> domain search
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Date: Sun, 25 Feb 2024 16:56:12 +0100
>
> The recent restriction to invoke irqdomain_ops::select() only when the
> domain bus toke is DOMAIN_BUS_ANY breaks the search for the parent MSI
> domain of HPET and IO-APIC. The latter causes a full boot fail.
>
> The restriction itself makes sense to avoid adding DOMAIN_BUS_ANY 
> matches
> into the various ARM specific select() callbacks. Reverting this change
> would obviously break ARM platforms again and require DOMAIN_BUS_ANY
> matches added to various places.
>
> A simpler solution is to use the DOMAIN_BUS_GENERIC_MSI token for the 
> HPET
> and IO-APIC parent domain search. This works out of the box because the
> affected parent domains check only for the firmware specification 
> content
> and not for the bus token.
>
> Fixes: 5aa3c0cf5bba ("genirq/irqdomain: Don't call ops->select for
> DOMAIN_BUS_ANY tokens")
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Looks good to me.

Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>

        M.
--
Jazz is not dead. It just smells funny...