• Vitaly Kuznetsov's avatar
    x86/ioapic: Disable interrupts when re-routing legacy IRQs · c0ff971e
    Vitaly Kuznetsov authored
    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: default avatarVitaly 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.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    c0ff971e
io_apic.c 76.9 KB