KVM: Add statistics for guest irq injections

These can help show whether a guest is making progress or not.

Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index b6d26b8..68a3ac1 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -413,6 +413,7 @@
 	u32 insn_emulation;
 	u32 insn_emulation_fail;
 	u32 hypercalls;
+	u32 irq_injections;
 };
 
 struct descriptor_table {