On Wed, 13 Dec 2023 12:50:23 +0000 Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> wrote: > From: James Morse <james.morse@xxxxxxx> > > 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 > complicates 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@xxxxxxx> > Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx> > Tested-by: Miguel Luis <miguel.luis@xxxxxxxxxx> > Tested-by: Vishnu Pajjuri <vishnu@xxxxxxxxxxxxxxxxxxxxxx> > Tested-by: Jianyong Wu <jianyong.wu@xxxxxxx> > Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> > --- > drivers/irqchip/irq-gic-v3.c | 18 ++++++------------ > 1 file changed, 6 insertions(+), 12 deletions(-) > > diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c > index 98b0329b7154..ebecd4546830 100644 > --- a/drivers/irqchip/irq-gic-v3.c > +++ b/drivers/irqchip/irq-gic-v3.c > @@ -2420,21 +2420,15 @@ static int __init gic_acpi_match_gicc(union acpi_subtable_headers *header, > > /* > * If GICC is enabled and has valid gicr base address, then it means > - * GICR base is presented via GICC > + * GICR base is presented via GICC. The redistributor is only known to > + * be accessible if the GICC is marked as enabled. If this bit is not > + * set, we'd need to add the redistributor at runtime, which isn't > + * supported. > */ > - if (acpi_gicc_is_usable(gicc) && gicc->gicr_base_address) { > + if (gicc->flags & ACPI_MADT_ENABLED && gicc->gicr_base_address) I was very vague in previous review. I think the reasons you are switching from acpi_gicc_is_useable(gicc) to the gicc->flags & ACPI_MADT_ENABLED needs calling out as I'm fairly sure that this point in the series at least acpi_gicc_is_usable is same as current upstream: static inline bool acpi_gicc_is_usable(struct acpi_madt_generic_interrupt *gicc) { return gicc->flags & ACPI_MADT_ENABLED; } > acpi_data.enabled_rdists++; > - return 0; > - } > > - /* > - * It's perfectly valid firmware can pass disabled GICC entry, driver > - * should not treat as errors, skip the entry instead of probe fail. > - */ > - if (!acpi_gicc_is_usable(gicc)) > - return 0; > - > - return -ENODEV; > + return 0; > } > > static int __init gic_acpi_count_gicr_regions(void)