• Marc Zyngier's avatar
    arm/arm64: KVM: detect CPU reset on CPU_PM_EXIT · b20c9f29
    Marc Zyngier authored
    Commit 1fcf7ce0 (arm: kvm: implement CPU PM notifier) added
    support for CPU power-management, using a cpu_notifier to re-init
    KVM on a CPU that entered CPU idle.
    The code assumed that a CPU entering idle would actually be powered
    off, loosing its state entierely, and would then need to be
    reinitialized. It turns out that this is not always the case, and
    some HW performs CPU PM without actually killing the core. In this
    case, we try to reinitialize KVM while it is still live. It ends up
    badly, as reported by Andre Przywara (using a Calxeda Midway):
    [    3.663897] Kernel panic - not syncing: unexpected prefetch abort in Hyp mode at: 0x685760
    [    3.663897] unexpected data abort in Hyp mode at: 0xc067d150
    [    3.663897] unexpected HVC/SVC trap in Hyp mode at: 0xc0901dd0
    The trick here is to detect if we've been through a full re-init or
    not by looking at HVBAR (VBAR_EL2 on arm64). This involves
    implementing the backend for __hyp_get_vectors in the main KVM HYP
    code (rather small), and checking the return value against the
    default one when the CPU notifier is called on CPU_PM_EXIT.
    Reported-by: default avatarAndre Przywara <osp@andrep.de>
    Tested-by: default avatarAndre Przywara <osp@andrep.de>
    Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
    Cc: Rob Herring <rob.herring@linaro.org>
    Acked-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
    Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
arm.c 23.3 KB