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    x86/irq: Seperate unused system vectors from spurious entry again · fc6975ee
    Thomas Gleixner 提交于
    commit f8a8fe61fec8006575699559ead88b0b833d5cad upstream
    
    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: 2414e021 ("x86: Avoid building unused IRQ entry stubs")
    Reported-by: NJan Kiszka <jan.kiszka@siemens.com>
    Signed-off-by: NThomas 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.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    
    fc6975ee
apic.c 68.1 KB