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Subject[patch] x86, apic: cleanup cfg->domain setup for legacy interrupts
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Had this cleanup patch (tested before by me and Boris aswell) for a
while. Forgot to post this earlier. Thanks.
---8<---

From: Suresh Siddha <suresh.b.siddha@intel.com>
Subject: x86, apic: cleanup cfg->domain setup for legacy interrupts

Issues that need to be handled:
* Handle PIC interrupts on any CPU irrespective of the apic mode
* In the apic lowest priority logical flat delivery mode, be prepared to
handle the interrupt on any CPU irrespective of what the IO-APIC RTE says.
* Because of above, when the IO-APIC starts handling the legacy PIC interrupt,
use the same vector that is being used by the PIC while programming the
corresponding IO-APIC RTE.

Start with all the cpu's in the legacy PIC interrupts cfg->domain.

By the time IO-APIC starts taking over the PIC interrupts, apic driver
model is finalized. So depend on the assign_irq_vector() to update the
cfg->domain and retain the same vector that was used by PIC before.

For the logical apic flat mode, cfg->domain is updated (during the first
call to assign_irq_vector()) to contain all the possible online cpu's (0xff).
Vector used for the legacy PIC interrupt doesn't change when the IO-APIC
starts handling the interrupt. Any interrupt migration after that
doesn't change the cfg->domain or the vector used.

For other apic modes like physical mode, cfg->domain is updated
(during the first call to assign_irq_vector()) to the boot cpu (cpu-0),
with the same vector that is being used by the PIC. When that interrupt is
migrated to a different cpu, cfg->domin and the vector assigned will change
accordingly.

Tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---
arch/x86/kernel/apic/io_apic.c | 26 ++++++--------------------
1 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index c265593..0c1f366 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -234,11 +234,11 @@ int __init arch_early_irq_init(void)
zalloc_cpumask_var_node(&cfg[i].old_domain, GFP_KERNEL, node);
/*
* For legacy IRQ's, start with assigning irq0 to irq15 to
- * IRQ0_VECTOR to IRQ15_VECTOR on cpu 0.
+ * IRQ0_VECTOR to IRQ15_VECTOR for all cpu's.
*/
if (i < legacy_pic->nr_legacy_irqs) {
cfg[i].vector = IRQ0_VECTOR + i;
- cpumask_set_cpu(0, cfg[i].domain);
+ cpumask_setall(cfg[i].domain);
}
}

@@ -1141,7 +1141,8 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
* allocation for the members that are not used anymore.
*/
cpumask_andnot(cfg->old_domain, cfg->domain, tmp_mask);
- cfg->move_in_progress = 1;
+ cfg->move_in_progress =
+ cpumask_intersects(cfg->old_domain, cpu_online_mask);
cpumask_and(cfg->domain, cfg->domain, tmp_mask);
break;
}
@@ -1172,8 +1173,9 @@ next:
current_vector = vector;
current_offset = offset;
if (cfg->vector) {
- cfg->move_in_progress = 1;
cpumask_copy(cfg->old_domain, cfg->domain);
+ cfg->move_in_progress =
+ cpumask_intersects(cfg->old_domain, cpu_online_mask);
}
for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask)
per_cpu(vector_irq, new_cpu)[vector] = irq;
@@ -1241,12 +1243,6 @@ void __setup_vector_irq(int cpu)
cfg = irq_get_chip_data(irq);
if (!cfg)
continue;
- /*
- * If it is a legacy IRQ handled by the legacy PIC, this cpu
- * will be part of the irq_cfg's domain.
- */
- if (irq < legacy_pic->nr_legacy_irqs && !IO_APIC_IRQ(irq))
- cpumask_set_cpu(cpu, cfg->domain);

if (!cpumask_test_cpu(cpu, cfg->domain))
continue;
@@ -1356,16 +1352,6 @@ static void setup_ioapic_irq(unsigned int irq, struct irq_cfg *cfg,
if (!IO_APIC_IRQ(irq))
return;

- /*
- * For legacy irqs, cfg->domain starts with cpu 0. Now that IO-APIC
- * can handle this irq and the apic driver is finialized at this point,
- * update the cfg->domain.
- */
- if (irq < legacy_pic->nr_legacy_irqs &&
- cpumask_equal(cfg->domain, cpumask_of(0)))
- apic->vector_allocation_domain(0, cfg->domain,
- apic->target_cpus());
-
if (assign_irq_vector(irq, cfg, apic->target_cpus()))
return;




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