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[Xen-devel] xen irq unmask bug brainstroming
| To: | Jeremy Fitzhardinge <jeremy@xxxxxxxx> |
|---|---|
| Subject: | [Xen-devel] xen irq unmask bug brainstroming |
| From: | "Zhang, Fengzhe" <fengzhe.zhang@xxxxxxxxx> |
| Date: | Tue, 15 Feb 2011 14:28:38 +0800 |
| Accept-language: | en-US |
| Acceptlanguage: | en-US |
| Cc: | xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Dong, Eddie" <eddie.dong@xxxxxxxxx>, "Li, Xin" <xin.li@xxxxxxxxx> |
| Delivery-date: | Mon, 14 Feb 2011 22:30:58 -0800 |
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| Thread-index: | AcvM2ZTujt8rvPiVTkSeHHLljh1sDw== |
| Thread-topic: | xen irq unmask bug brainstroming |
Hi, we found a bug related to xen spin unlock ipi. Looking forward to brainstorming for a clean fixup. How the bug happens: 1. Dom0 poweroff. 2. CPU0 takes down other CPUs. 3. IRQs are unmasked in function fixup_irqs on other CPUs. 4. IPI IRQ for "lock_kicker_irq" is unmasked (which should never happen). 5. Other CPUs receives lock_kicker_irq and dummy_handler (handler for ipi XEN_SPIN_UNLOCK_VECTOR) is invoked. 6. Dummy_handler reports bug and crashes Dom0. Main cause: Function fixup_irqs masks and then unmasks each irq when taking cpus down. And Xen irq_chip structure does not distinguish disable_ops from mask_ops. So when the lock_kicker_irq is unmasked, it is effectively re-enabled. A possible fixup: Provide a dedicated disable_ops for xen irq_chip structure. Prevent unmask_ops to enable irqs that are disabled. -Fengzhe Zhang _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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