s390x/kvm: add interface for clearing IO irqs

According to the platform specification, under certain conditions,
pending IO interruptions have to be cleared. Let's add an interface
for that.
Signed-off-by: NHalil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>

hw/intc/s390_flic.c

@@ -67,6 +67,13 @@ static void qemu_s390_release_adapter_routes(S390FLICState *fs,
 {
 }
 
+static int qemu_s390_clear_io_flic(S390FLICState *fs, uint16_t subchannel_id,
+                           uint16_t subchannel_nr)
+{
+    /* Fixme TCG */
+    return -ENOSYS;
+}
+
 static void qemu_s390_flic_class_init(ObjectClass *oc, void *data)
 {
     S390FLICStateClass *fsc = S390_FLIC_COMMON_CLASS(oc);
@@ -75,6 +82,7 @@ static void qemu_s390_flic_class_init(ObjectClass *oc, void *data)
     fsc->io_adapter_map = qemu_s390_io_adapter_map;
     fsc->add_adapter_routes = qemu_s390_add_adapter_routes;
     fsc->release_adapter_routes = qemu_s390_release_adapter_routes;
+    fsc->clear_io_irq = qemu_s390_clear_io_flic;
 }
 
 static const TypeInfo qemu_s390_flic_info = {

hw/intc/s390_flic_kvm.c

@@ -30,6 +30,7 @@ typedef struct KVMS390FLICState {
     S390FLICState parent_obj;
 
     uint32_t fd;
+    bool clear_io_supported;
 } KVMS390FLICState;
 
 DeviceState *s390_flic_kvm_create(void)
@@ -130,6 +131,24 @@ int kvm_s390_inject_flic(struct kvm_s390_irq *irq)
     return flic_enqueue_irqs(irq, sizeof(*irq), flic);
 }
 
+static int kvm_s390_clear_io_flic(S390FLICState *fs, uint16_t subchannel_id,
+                           uint16_t subchannel_nr)
+{
+    KVMS390FLICState *flic = KVM_S390_FLIC(fs);
+    int rc;
+    uint32_t sid = subchannel_id << 16 | subchannel_nr;
+    struct kvm_device_attr attr = {
+        .group = KVM_DEV_FLIC_CLEAR_IO_IRQ,
+        .addr = (uint64_t) &sid,
+        .attr = sizeof(sid),
+    };
+    if (unlikely(!flic->clear_io_supported)) {
+        return -ENOSYS;
+    }
+    rc = ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr);
+    return rc ? -errno : 0;
+}
+
 /**
  * __get_all_irqs - store all pending irqs in buffer
  * @flic: pointer to flic device state
@@ -358,6 +377,7 @@ static void kvm_s390_flic_realize(DeviceState *dev, Error **errp)
 {
     KVMS390FLICState *flic_state = KVM_S390_FLIC(dev);
     struct kvm_create_device cd = {0};
+    struct kvm_device_attr test_attr = {0};
     int ret;
 
     flic_state->fd = -1;
@@ -374,6 +394,11 @@ static void kvm_s390_flic_realize(DeviceState *dev, Error **errp)
     }
     flic_state->fd = cd.fd;
 
+    /* Check clear_io_irq support */
+    test_attr.group = KVM_DEV_FLIC_CLEAR_IO_IRQ;
+    flic_state->clear_io_supported = !ioctl(flic_state->fd,
+                                            KVM_HAS_DEVICE_ATTR, test_attr);
+
     /* Register savevm handler for floating interrupts */
     register_savevm(NULL, "s390-flic", 0, 1, kvm_flic_save,
                     kvm_flic_load, (void *) flic_state);
@@ -420,6 +445,7 @@ static void kvm_s390_flic_class_init(ObjectClass *oc, void *data)
     fsc->io_adapter_map = kvm_s390_io_adapter_map;
     fsc->add_adapter_routes = kvm_s390_add_adapter_routes;
     fsc->release_adapter_routes = kvm_s390_release_adapter_routes;
+    fsc->clear_io_irq = kvm_s390_clear_io_flic;
 }
 
 static const TypeInfo kvm_s390_flic_info = {

include/hw/s390x/s390_flic.h

@@ -49,6 +49,8 @@ typedef struct S390FLICStateClass {
                           bool do_map);
     int (*add_adapter_routes)(S390FLICState *fs, AdapterRoutes *routes);
     void (*release_adapter_routes)(S390FLICState *fs, AdapterRoutes *routes);
+    int (*clear_io_irq)(S390FLICState *fs, uint16_t subchannel_id,
+                        uint16_t subchannel_nr);
 } S390FLICStateClass;
 
 #define TYPE_KVM_S390_FLIC "s390-flic-kvm"