Messages in this thread | | | From | Ganapatrao Kulkarni <> | Date | Wed, 20 Dec 2017 15:04:52 +0530 | Subject | Re: [PATCH] irqchip/gic-v3-its: Flush GICR caching for a cross node collection move of an irq |
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Hi Marc,
On Wed, Dec 20, 2017 at 2:56 PM, Marc Zyngier <marc.zyngier@arm.com> wrote: > On 20/12/17 09:15, Ganapatrao Kulkarni wrote: >> When an interrupt is moved, it is possible that an implementation that >> supports caching might still have cached data for a previous >> (no longer valid) mapping of the interrupt. In particular, in a distributed >> GIC implementation like multi-socket SoC platfroms. Hence it is necessary >> to flush cached entries after cross node collection migration. >> >> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com> >> --- >> drivers/irqchip/irq-gic-v3-its.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c >> index 4039e64..ea849a1 100644 >> --- a/drivers/irqchip/irq-gic-v3-its.c >> +++ b/drivers/irqchip/irq-gic-v3-its.c >> @@ -1119,6 +1119,12 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val, >> if (cpu != its_dev->event_map.col_map[id]) { >> target_col = &its_dev->its->collections[cpu]; >> its_send_movi(its_dev, target_col, id); >> + /* Issue INV for cross node collection move on >> + * multi socket systems. >> + */ >> + if (cpu_to_node(cpu) != >> + cpu_to_node(its_dev->event_map.col_map[id])) >> + its_send_inv(its_dev, id); >> its_dev->event_map.col_map[id] = cpu; >> irq_data_update_effective_affinity(d, cpumask_of(cpu)); >> } >> > > The MOVI command doesn't have any such requirement (it only mandates > synchronization), and doesn't say anything about distributed vs monolithic.
GIC-v3 spec do mention to issue ITS INV command or a write to GICR_INVLPIR. pasting below snippet of MOVI command description.
"When an interrupt is moved to a collection, it is possible that an implementation that supports speculative caching might still have cached data for a previous (no longer valid) mapping of the interrupt. Hence, implementations must take care to invalidate any data associated with an interrupt when it is moved. In particular, in a distributed implementation, the ITS must write to the appropriate GICR_* register to perform the invalidation in the redistributor."
> > What am I missing? > > M. > -- > Jazz is not dead. It just smells funny...
thanks Ganapat
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