From: Vitaly Kuznetsov Date: Thu, 15 Oct 2015 17:42:23 +0000 (+0200) Subject: x86/ioapic: Disable interrupts when re-routing legacy IRQs X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c0ff971ef9acacd4d2caa508e444edad958dead9;p=linux-beck.git 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: [] ? trace_hardirqs_off+0xd/0x10 [] queue_work_on+0x46/0x90 [] ? add_interrupt_randomness+0x176/0x1d0 ... [] ? _raw_spin_unlock_irqrestore+0x3b/0x60 [] __irq_put_desc_unlock+0x1e/0x40 [] irq_modify_status+0xb5/0xd0 [] mp_register_handler+0x4b/0x70 [] mp_irqdomain_alloc+0x1ea/0x2a0 [] irq_domain_alloc_irqs_recursive+0x40/0xa0 [] __irq_domain_alloc_irqs+0x13c/0x2b0 [] alloc_isa_irq_from_domain.isra.1+0xc0/0xe0 [] mp_map_pin_to_irq+0x165/0x2d0 [] pin_2_irq+0x47/0x80 [] setup_IO_APIC+0xfe/0x802 ... [] ? 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 Cc: Jiang Liu Cc: Yinghai Lu Cc: K. Y. Srinivasan Link: http://lkml.kernel.org/r/1444930943-19336-1-git-send-email-vkuznets@redhat.com Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 5c60bb162622..bb6bfc01cb82 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; if (!info || nr_irqs > 1) return -EINVAL; @@ -2939,11 +2940,14 @@ 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); + + 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()) 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",