Public bug reported: A sporadic hang with consequent crash is observed when booting Hyper-V Gen1 guests...
Sauce request for upstream submission: https://lkml.org/lkml/2015/10/15/673 >From Vitaly Kuznetsov <> Subject [PATCH] x86/ioapic: Disable interrupts when re-routing legacy IRQs Date Thu, 15 Oct 2015 19:42:23 +0200 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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Jiang Liu <[email protected]> Cc: Yinghai Lu <[email protected]> Cc: K. Y. Srinivasan <[email protected]> Signed-off-by: Vitaly Kuznetsov <[email protected]> --- 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 ** Affects: linux-kernel (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1508593 Title: [Hyper-V] x86/ioapic: Disable interrupts when re-routing legacy IRQs To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-kernel/+bug/1508593/+subscriptions -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
