• H. Peter Anvin's avatar
    x86: Ignore NMIs that come in during early boot · 5fa10196
    H. Peter Anvin authored
    Don Zickus reports:
    
    A customer generated an external NMI using their iLO to test kdump
    worked.  Unfortunately, the machine hung.  Disabling the nmi_watchdog
    made things work.
    
    I speculated the external NMI fired, caused the machine to panic (as
    expected) and the perf NMI from the watchdog came in and was latched.
    My guess was this somehow caused the hang.
    
       ----
    
    It appears that the latched NMI stays latched until the early page
    table generation on 64 bits, which causes exceptions to happen which
    end in IRET, which re-enable NMI.  Therefore, ignore NMIs that come in
    during early execution, until we have proper exception handling.
    Reported-and-tested-by: default avatarDon Zickus <dzickus@redhat.com>
    Link: http://lkml.kernel.org/r/1394221143-29713-1-git-send-email-dzickus@redhat.comSigned-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
    Cc: <stable@vger.kernel.org> # v3.5+, older with some backport effort
    5fa10196
head_64.S 12.9 KB