On 21/02/14 17:12, Christoffer Dall wrote: > 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. Thanks. I'm thinking of pushing this to 3.14 as a fix. Any objection? M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
