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    x86, apic: Map the local apic when parsing the MP table. · 5989cd6a
    Eric W. Biederman 提交于
    This fixes a regression in 2.6.35 from 2.6.34, that is
    present for select models of Intel cpus when people are
    using an MP table.
    
    The commit cf7500c0
    "x86, ioapic: In mpparse use mp_register_ioapic" started
    calling mp_register_ioapic from MP_ioapic_info.  An extremely
    simple change that was obviously correct.  Unfortunately
    mp_register_ioapic did just a little more than the previous
    hand crafted code and so we gained this call path.
    
    The problem call path is:
    MP_ioapic_info()
      mp_register_ioapic()
       io_apic_unique_id()
         io_apic_get_unique_id()
           get_physical_broadcast()
             modern_apic()
               lapic_get_version()
                 apic_read(APIC_LVR)
    
    Which turned out to be a problem because the local apic
    was not mapped, at that point, unlike the similar point
    in the ACPI parsing code.
    
    This problem is fixed by mapping the local apic when
    parsing the mptable as soon as we reasonably can.
    
    Looking at the number of places we setup the fixmap for
    the local apic, I see some serious simplification opportunities.
    For the moment except for not duplicating the setting up of the
    fixmap in init_apic_mappings, I have not acted on them.
    
    The regression from 2.6.34 is tracked in bug
    https://bugzilla.kernel.org/show_bug.cgi?id=16173
    
    Cc: <stable@kernel.org> 2.6.35
    Reported-by: NDavid Hill <hilld@binarystorm.net>
    Reported-by: NTvrtko Ursulin <tvrtko.ursulin@sophos.com>
    Tested-by: NTvrtko Ursulin <tvrtko.ursulin@sophos.com>
    Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
    LKML-Reference: <m1eiee86jg.fsf_-_@fess.ebiederm.org>
    Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
    5989cd6a
mpparse.c 23.9 KB