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irqchip/gic-v2, v3: Implement irq_chip->irq_retrigger() 

While digging around IRQCHIP_EOI_IF_HANDLED and irq/resend.c, it has come
to my attention that the IRQ resend situation seems a bit precarious for
the GIC(s).

When marking an IRQ with IRQS_PENDING, handle_fasteoi_irq() will bail out
and issue an irq_eoi(). Should the IRQ in question be re-enabled,
check_irq_resend() will trigger a SW resend, which will go through the flow
handler again and issue *another* irq_eoi() on the *same* IRQ
activation. This is something the GIC spec clearly describes as a bad idea:
any EOI must match a previous ACK.

Implement irq_chip.irq_retrigger() for the GIC chips by setting the GIC
pending bit of the relevant IRQ. After being called by check_irq_resend(),
this will eventually trigger a *new* interrupt which we will handle as usual.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200730170321.31228-2-valentin.schneider@arm.com
This commit is contained in:
Valentin Schneider 2020-07-30 18:03:20 +01:00 committed by Marc Zyngier
parent cd1752d34e
commit 17f644e949
2 changed files with 13 additions and 0 deletions
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7
drivers/irqchip/irq-gic-v3.c
View File

@ -1207,6 +1207,11 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
#define gic_smp_init() do { } while(0)
#endif
static int gic_retrigger(struct irq_data *data)
{
return !gic_irq_set_irqchip_state(data, IRQCHIP_STATE_PENDING, true);
}
#ifdef CONFIG_CPU_PM
static int gic_cpu_pm_notifier(struct notifier_block *self,
unsigned long cmd, void *v)
@ -1242,6 +1247,7 @@ static struct irq_chip gic_chip = {
.irq_eoi = gic_eoi_irq,
.irq_set_type = gic_set_type,
.irq_set_affinity = gic_set_affinity,
.irq_retrigger = gic_retrigger,
.irq_get_irqchip_state = gic_irq_get_irqchip_state,
.irq_set_irqchip_state = gic_irq_set_irqchip_state,
.irq_nmi_setup = gic_irq_nmi_setup,
@ -1258,6 +1264,7 @@ static struct irq_chip gic_eoimode1_chip = {
.irq_eoi = gic_eoimode1_eoi_irq,
.irq_set_type = gic_set_type,
.irq_set_affinity = gic_set_affinity,
.irq_retrigger = gic_retrigger,
.irq_get_irqchip_state = gic_irq_get_irqchip_state,
.irq_set_irqchip_state = gic_irq_set_irqchip_state,
.irq_set_vcpu_affinity = gic_irq_set_vcpu_affinity,

6
drivers/irqchip/irq-gic.c
View File

@ -347,6 +347,11 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
}
#endif
static int gic_retrigger(struct irq_data *data)
{
return !gic_irq_set_irqchip_state(data, IRQCHIP_STATE_PENDING, true);
}
static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
{
u32 irqstat, irqnr;
@ -417,6 +422,7 @@ static const struct irq_chip gic_chip = {
.irq_unmask = gic_unmask_irq,
.irq_eoi = gic_eoi_irq,
.irq_set_type = gic_set_type,
.irq_retrigger = gic_retrigger,
.irq_get_irqchip_state = gic_irq_get_irqchip_state,
.irq_set_irqchip_state = gic_irq_set_irqchip_state,
.flags = IRQCHIP_SET_TYPE_MASKED |