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Subjectx86: Spurious vectors not handled robustly
Hi all,

probably since "x86: Avoid building unused IRQ entry stubs" (2414e021ac8d), the
kernel can no longer tell spurious IRQs by the APIC apart from spuriously
triggered unused vectors. We've managed to trigger such a cause with the
Jailhouse hypervisor (incorrectly injected MANAGED_IRQ_SHUTDOWN_VECTOR), and the
result was not only a misreport of the vector number (0xff instead of 0xef -
took me a while...), but also stalled interrupts of equal and lower priority
because a spurious interrupt is not (and must not be) acknowledged.

How to address that best? I would say we should at least have separate entry
paths for APIC interrupt vs. vectors, to improve robustness in the faulty case.


Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux

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