On Fri, Feb 21, 2014 at 11:46:56AM +0000, Marc Zyngier wrote: > Commit 1fcf7ce0c602 (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: Andre Przywara <osp@xxxxxxxxx> > Tested-by: Andre Przywara <osp@xxxxxxxxx> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > Cc: Rob Herring <rob.herring@xxxxxxxxxx> > Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> Thanks! Looks good. -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
