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    Subject[PATCH v2 0/2] x86/apic: reset LDR in clear_local_APIC
    Date
    v2:
    1/2: clear out the bogus initialization in bigsmp_init_apic_ldr
    2/2: reword commit message as suggested by Thomas
    v1 posted at https://lkml.org/lkml/2019/8/14/1

    On a 32 bit RHEL6 guest with greater than 8 cpus, the
    kdump kernel hangs when calibrating apic. This happens
    because when apic initializes bigsmp, it also initializes LDR
    even though it probably wouldn't be used.

    When booting into kdump, KVM apic incorrectly reads the stale LDR
    values from the guest while building the logical destination map
    even for inactive vcpus. While KVM apic can be fixed to ignore apics
    that haven't been enabled, a simple guest only change can be to
    just clear out the LDR.

    Bandan Das (2):
    x86/apic: Do not initialize LDR and DFR for bigsmp
    x86/apic: include the LDR when clearing out apic registers

    arch/x86/kernel/apic/apic.c | 4 ++++
    arch/x86/kernel/apic/bigsmp_32.c | 24 ++----------------------
    2 files changed, 6 insertions(+), 22 deletions(-)

    --
    2.20.1

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