KVM: add support for any length io eventfd

Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/kvm.h

@@ -53,6 +53,7 @@ extern bool kvm_gsi_routing_allowed;
 extern bool kvm_gsi_direct_mapping;
 extern bool kvm_readonly_mem_allowed;
 extern bool kvm_direct_msi_allowed;
+extern bool kvm_ioeventfd_any_length_allowed;
 
 #if defined CONFIG_KVM || !defined NEED_CPU_H
 #define kvm_enabled()           (kvm_allowed)
@@ -153,6 +154,12 @@ extern bool kvm_direct_msi_allowed;
  */
 #define kvm_direct_msi_enabled() (kvm_direct_msi_allowed)
 
+/**
+ * kvm_ioeventfd_any_length_enabled:
+ * Returns: true if KVM allows any length io eventfd.
+ */
+#define kvm_ioeventfd_any_length_enabled() (kvm_ioeventfd_any_length_allowed)
+
 #else
 #define kvm_enabled()           (0)
 #define kvm_irqchip_in_kernel() (false)
@@ -166,6 +173,7 @@ extern bool kvm_direct_msi_allowed;
 #define kvm_gsi_direct_mapping() (false)
 #define kvm_readonly_mem_enabled() (false)
 #define kvm_direct_msi_enabled() (false)
+#define kvm_ioeventfd_any_length_enabled() (false)
 #endif
 
 struct kvm_run;

kvm-all.c

@@ -109,6 +109,7 @@ bool kvm_allowed;
 bool kvm_readonly_mem_allowed;
 bool kvm_vm_attributes_allowed;
 bool kvm_direct_msi_allowed;
+bool kvm_ioeventfd_any_length_allowed;
 
 static const KVMCapabilityInfo kvm_required_capabilites[] = {
     KVM_CAP_INFO(USER_MEMORY),
@@ -1611,6 +1612,9 @@ static int kvm_init(MachineState *ms)
     kvm_vm_attributes_allowed =
         (kvm_check_extension(s, KVM_CAP_VM_ATTRIBUTES) > 0);
 
+    kvm_ioeventfd_any_length_allowed =
+        (kvm_check_extension(s, KVM_CAP_IOEVENTFD_ANY_LENGTH) > 0);
+
     ret = kvm_arch_init(ms, s);
     if (ret < 0) {
         goto err;

kvm-stub.c

@@ -30,6 +30,7 @@ bool kvm_gsi_routing_allowed;
 bool kvm_gsi_direct_mapping;
 bool kvm_allowed;
 bool kvm_readonly_mem_allowed;
+bool kvm_ioeventfd_any_length_allowed;
 
 int kvm_init_vcpu(CPUState *cpu)
 {