On 06/12/17 14:17, Andre Przywara wrote: > Hi, > > On 06/12/17 14:11, Andre Przywara wrote: >> Hi, >> >> while trying to boot 4.15-rc1 on my Calxeda Midway I observed a crash >> (see below). I can't look further into this today, but wanted to report >> this anyway. >> >> Digging around a bit this is due to the VGIC not initializing properly >> due to GICC being advertised as just 4K, not 8K. >> This can be worked around by adjusting the DT or using >> irqchip.gicv2_force_probe. However this still raises some questions: >> 1) Even if the VGIC fails to register, we should certainly not crash. >> The chain of events seems to be: >> virt/kvm/arm/arm.c:init_subsystems(): >> - kvm_vgic_hyp_init() returns -ENODEV, this leads to vgic_present >> being set to false, but "err" being reset to 0 (meaning: carry on). >> However this seems now to miss some initialization. >> - kvm_timer_hyp_init() now fails on calling irq_set_vcpu_affinity(), >> because this returns -ENOSYS. This leads to it returning this error, >> init_subsystems() failing and subsequently tearing down KVM. >> - This seems to have some bug and leads to the kernel crash. >> >> Even with the VGIC not being usable, we should be able to cleanly tear >> down KVM (or HYP?). > > Just checked: If I let kvm_timer_hyp_init() deliberately fail in 4.14, I > get the same splat (4.14 works fine, otherwise). So this particular > issue existed already before. You should be able to reproduce it on any > box by forcing "err = -ENOSYS;" after the call to kvm_timer_hyp_init() > in virt/kvm/arm/arm.c:init_subsystems(). I wonder if the bigger hammer-type solution is not to expose that the GIC is not capable of EOImode==1, and not enable the vgic in that particular case... I'll cook an RFC patch set for you to test. Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
