x86/ioapic: Disable interrupts when re-routing legacy IRQs
authorVitaly Kuznetsov <vkuznets@redhat.com>
Thu, 15 Oct 2015 17:42:23 +0000 (19:42 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Fri, 16 Oct 2015 14:31:24 +0000 (16:31 +0200)
commitc0ff971ef9acacd4d2caa508e444edad958dead9
tree9b9a890cfaf1c095149bdd49b50edfffeb5c8f06
parent1a800589052f03ce09008f82ad2c69f0af5d315a
x86/ioapic: Disable interrupts when re-routing legacy IRQs

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.

Protect the setup sequence against concurrent interrupts.

[ tglx: Make the protection unconditional and not only for legacy
   interrupts ]

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1444930943-19336-1-git-send-email-vkuznets@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
arch/x86/kernel/apic/io_apic.c