public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
* [PATCH] x86/ioapic: Disable interrupts when re-routing legacy IRQs
@ 2015-10-15 17:42 Vitaly Kuznetsov
  2015-10-16 14:33 ` [tip:x86/urgent] " tip-bot for Vitaly Kuznetsov
  0 siblings, 1 reply; 2+ messages in thread
From: Vitaly Kuznetsov @ 2015-10-15 17:42 UTC (permalink / raw)
  To: x86
  Cc: linux-kernel, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
	Jiang Liu, Yinghai Lu, K. Y. Srinivasan

A sporadic hang with consequent crash is observed when booting Hyper-V Gen1
guests:

 Call Trace:
  <IRQ>
  [<ffffffff810ab68d>] ? trace_hardirqs_off+0xd/0x10
  [<ffffffff8107b616>] queue_work_on+0x46/0x90
  [<ffffffff81365696>] ? add_interrupt_randomness+0x176/0x1d0
  ...
  <EOI>
  [<ffffffff81471ddb>] ? _raw_spin_unlock_irqrestore+0x3b/0x60
  [<ffffffff810c295e>] __irq_put_desc_unlock+0x1e/0x40
  [<ffffffff810c5c35>] irq_modify_status+0xb5/0xd0
  [<ffffffff8104adbb>] mp_register_handler+0x4b/0x70
  [<ffffffff8104c55a>] mp_irqdomain_alloc+0x1ea/0x2a0
  [<ffffffff810c7f10>] irq_domain_alloc_irqs_recursive+0x40/0xa0
  [<ffffffff810c860c>] __irq_domain_alloc_irqs+0x13c/0x2b0
  [<ffffffff8104b070>] alloc_isa_irq_from_domain.isra.1+0xc0/0xe0
  [<ffffffff8104bfa5>] mp_map_pin_to_irq+0x165/0x2d0
  [<ffffffff8104c157>] pin_2_irq+0x47/0x80
  [<ffffffff81744253>] setup_IO_APIC+0xfe/0x802
  ...
  [<ffffffff814631c0>] ? rest_init+0x140/0x140

The issue is easily reproducible with a simple instrumentation: if
mdelay(10) is put between mp_setup_entry() and mp_register_handler() calls
in mp_irqdomain_alloc() Hyper-V guest always fails to boot when re-routing
IRQ0. The issue seems to be caused by the fact that we don't disable
interrupts while doing IOPIC programming for legacy IRQs and IRQ0 actually
happens. Decorate manipulations with legacy IRQs with local_irq_save()/
local_irq_restore().

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
It may make sense to have interrupts disabled for non-legacy IRQs as well
but I'm unaware of any bugs with them at this moment.
---
 arch/x86/kernel/apic/io_apic.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 5c60bb1..9aac777 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2907,6 +2907,7 @@ int mp_irqdomain_alloc(struct irq_domain *domain, unsigned int virq,
 	struct irq_data *irq_data;
 	struct mp_chip_data *data;
 	struct irq_alloc_info *info = arg;
+	unsigned long flags = 0;
 
 	if (!info || nr_irqs > 1)
 		return -EINVAL;
@@ -2939,11 +2940,16 @@ int mp_irqdomain_alloc(struct irq_domain *domain, unsigned int virq,
 
 	cfg = irqd_cfg(irq_data);
 	add_pin_to_irq_node(data, ioapic_alloc_attr_node(info), ioapic, pin);
+
+	if (virq < nr_legacy_irqs())
+		local_irq_save(flags);
 	if (info->ioapic_entry)
 		mp_setup_entry(cfg, data, info->ioapic_entry);
 	mp_register_handler(virq, data->trigger);
-	if (virq < nr_legacy_irqs())
+	if (virq < nr_legacy_irqs()) {
 		legacy_pic->mask(virq);
+		local_irq_restore(flags);
+	}
 
 	apic_printk(APIC_VERBOSE, KERN_DEBUG
 		    "IOAPIC[%d]: Set routing entry (%d-%d -> 0x%x -> IRQ %d Mode:%i Active:%i Dest:%d)\n",
-- 
2.4.3


^ permalink raw reply related	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2015-10-16 14:33 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-10-15 17:42 [PATCH] x86/ioapic: Disable interrupts when re-routing legacy IRQs Vitaly Kuznetsov
2015-10-16 14:33 ` [tip:x86/urgent] " tip-bot for Vitaly Kuznetsov

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox