kvm: test for ioeventfd support on old kernels

There used to be a limit of 6 KVM io bus devices in the kernel.
On such a kernel, we can't use many ioeventfds for host notification
since the limit is reached too easily.

Add an API to test for this condition.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/kvm.h b/kvm.h
index 60a9b425c8..ce08d42756 100644
--- a/kvm.h
+++ b/kvm.h
@@ -42,6 +42,7 @@ int kvm_has_robust_singlestep(void);
 int kvm_has_debugregs(void);
 int kvm_has_xsave(void);
 int kvm_has_xcrs(void);
+int kvm_has_many_ioeventfds(void);
 
 #ifdef NEED_CPU_H
 int kvm_init_vcpu(CPUState *env);