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Date: Fri, 2 Feb 2024 16:44:31 +0000
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
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Subject: Re: [PATCH RFC v4 10/15] irqchip/gic-v3: Don't return errors from
 gic_acpi_match_gicc()
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	<E1rVDn9-0027ZB-QN@rmk-PC.armlinux.org.uk>
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On Wed, 31 Jan 2024 16:50:27 +0000
Russell King (Oracle) <rmk+kernel@armlinux.org.uk> wrote:

> From: James Morse <james.morse@arm.com>
> 
> gic_acpi_match_gicc() is only called via gic_acpi_count_gicr_regions().
> It should only count the number of enabled redistributors, but it
> also tries to sanity check the GICC entry, currently returning an
> error if the Enabled bit is set, but the gicr_base_address is zero.
> 
> Adding support for the online-capable bit to the sanity check will
> complicate it, for no benefit. The existing check implicitly depends on
> gic_acpi_count_gicr_regions() previous failing to find any GICR regions
> (as it is valid to have gicr_base_address of zero if the redistributors
> are described via a GICR entry).
> 
> Instead of complicating the check, remove it. Failures that happen at
> this point cause the irqchip not to register, meaning no irqs can be
> requested. The kernel grinds to a panic() pretty quickly.
> 
> Without the check, MADT tables that exhibit this problem are still
> caught by gic_populate_rdist(), which helpfully also prints what went
> wrong:
> | CPU4: mpidr 100 has no re-distributor!
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Does what it says on the tin.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>