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, 5 insertions, 0 deletions

diff --git a/kvm-stub.c b/kvm-stub.c
index 5384a4b9a4..33d4476fa3 100644
--- a/kvm-stub.c
+++ b/kvm-stub.c
@@ -99,6 +99,11 @@ int kvm_has_robust_singlestep(void)
     return 0;
 }
 
+int kvm_has_many_ioeventfds(void)
+{
+    return 0;
+}
+
 void kvm_setup_guest_memory(void *start, size_t size)
 {
 }