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commitf8a8fe61feupstream Quite some time ago the interrupt entry stubs for unused vectors in the system vector range got removed and directly mapped to the spurious interrupt vector entry point. Sounds reasonable, but it's subtly broken. The spurious interrupt vector entry point pushes vector number 0xFF on the stack which makes the whole logic in __smp_spurious_interrupt() pointless. As a consequence any spurious interrupt which comes from a vector != 0xFF is treated as a real spurious interrupt (vector 0xFF) and not acknowledged. That subsequently stalls all interrupt vectors of equal and lower priority, which brings the system to a grinding halt. This can happen because even on 64-bit the system vector space is not guaranteed to be fully populated. A full compile time handling of the unused vectors is not possible because quite some of them are conditonally populated at runtime. Bring the entry stubs back, which wastes 160 bytes if all stubs are unused, but gains the proper handling back. There is no point to selectively spare some of the stubs which are known at compile time as the required code in the IDT management would be way larger and convoluted. Do not route the spurious entries through common_interrupt and do_IRQ() as the original code did. Route it to smp_spurious_interrupt() which evaluates the vector number and acts accordingly now that the real vector numbers are handed in. Fixup the pr_warn so the actual spurious vector (0xff) is clearly distiguished from the other vectors and also note for the vectored case whether it was pending in the ISR or not. "Spurious APIC interrupt (vector 0xFF) on CPU#0, should never happen." "Spurious interrupt vector 0xed on CPU#1. Acked." "Spurious interrupt vector 0xee on CPU#1. Not pending!." Fixes:2414e021ac("x86: Avoid building unused IRQ entry stubs") Reported-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Jan Beulich <jbeulich@suse.com> Link: https://lkml.kernel.org/r/20190628111440.550568228@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.