diff options
Diffstat (limited to 'arch/x86/kvm/xen.c')
| -rw-r--r-- | arch/x86/kvm/xen.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 9b029bb29a16..5fa2cca43653 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1971,8 +1971,19 @@ int kvm_xen_setup_evtchn(struct kvm *kvm, { struct kvm_vcpu *vcpu; - if (ue->u.xen_evtchn.port >= max_evtchn_port(kvm)) - return -EINVAL; + /* + * Don't check for the port being within range of max_evtchn_port(). + * Userspace can configure what ever targets it likes; events just won't + * be delivered if/while the target is invalid, just like userspace can + * configure MSIs which target non-existent APICs. + * + * This allow on Live Migration and Live Update, the IRQ routing table + * can be restored *independently* of other things like creating vCPUs, + * without imposing an ordering dependency on userspace. In this + * particular case, the problematic ordering would be with setting the + * Xen 'long mode' flag, which changes max_evtchn_port() to allow 4096 + * instead of 1024 event channels. + */ /* We only support 2 level event channels for now */ if (ue->u.xen_evtchn.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL) |