KVM: PIT: provide an option to disable interrupt reinjection
Certain clocks (such as TSC) in older 2.6 guests overaccount for lost
ticks, causing severe time drift. Interrupt reinjection magnifies the
problem.
Provide an option to disable it.
[avi: allow room for expansion in case we want to disable reinjection
of other timers]
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c3fbe8c..a1f1461 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -993,6 +993,7 @@
case KVM_CAP_NOP_IO_DELAY:
case KVM_CAP_MP_STATE:
case KVM_CAP_SYNC_MMU:
+ case KVM_CAP_REINJECT_CONTROL:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -1728,6 +1729,15 @@
return r;
}
+static int kvm_vm_ioctl_reinject(struct kvm *kvm,
+ struct kvm_reinject_control *control)
+{
+ if (!kvm->arch.vpit)
+ return -ENXIO;
+ kvm->arch.vpit->pit_state.pit_timer.reinject = control->pit_reinject;
+ return 0;
+}
+
/*
* Get (and clear) the dirty memory log for a memory slot.
*/
@@ -1925,6 +1935,17 @@
r = 0;
break;
}
+ case KVM_REINJECT_CONTROL: {
+ struct kvm_reinject_control control;
+ r = -EFAULT;
+ if (copy_from_user(&control, argp, sizeof(control)))
+ goto out;
+ r = kvm_vm_ioctl_reinject(kvm, &control);
+ if (r)
+ goto out;
+ r = 0;
+ break;
+ }
default:
;
}