s390x/ap: Wire up the device request notifier interface

Let's wire up the device request notifier interface to handle device unplug
requests for AP.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20230530225544.280031-1-akrowiak@linux.ibm.com/
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/ap.c

@@ -18,6 +18,8 @@
 #include "hw/vfio/vfio-common.h"
 #include "hw/s390x/ap-device.h"
 #include "qemu/error-report.h"
+#include "qemu/event_notifier.h"
+#include "qemu/main-loop.h"
 #include "qemu/module.h"
 #include "qemu/option.h"
 #include "qemu/config-file.h"
@@ -33,6 +35,7 @@
 struct VFIOAPDevice {
     APDevice apdev;
     VFIODevice vdev;
+    EventNotifier req_notifier;
 };
 
 OBJECT_DECLARE_SIMPLE_TYPE(VFIOAPDevice, VFIO_AP_DEVICE)
@@ -84,10 +87,110 @@ static VFIOGroup *vfio_ap_get_group(VFIOAPDevice *vapdev, Error **errp)
     return vfio_get_group(groupid, &address_space_memory, errp);
 }
 
+static void vfio_ap_req_notifier_handler(void *opaque)
+{
+    VFIOAPDevice *vapdev = opaque;
+    Error *err = NULL;
+
+    if (!event_notifier_test_and_clear(&vapdev->req_notifier)) {
+        return;
+    }
+
+    qdev_unplug(DEVICE(vapdev), &err);
+
+    if (err) {
+        warn_reportf_err(err, VFIO_MSG_PREFIX, vapdev->vdev.name);
+    }
+}
+
+static void vfio_ap_register_irq_notifier(VFIOAPDevice *vapdev,
+                                          unsigned int irq, Error **errp)
+{
+    int fd;
+    size_t argsz;
+    IOHandler *fd_read;
+    EventNotifier *notifier;
+    struct vfio_irq_info *irq_info;
+    VFIODevice *vdev = &vapdev->vdev;
+
+    switch (irq) {
+    case VFIO_AP_REQ_IRQ_INDEX:
+        notifier = &vapdev->req_notifier;
+        fd_read = vfio_ap_req_notifier_handler;
+        break;
+    default:
+        error_setg(errp, "vfio: Unsupported device irq(%d)", irq);
+        return;
+    }
+
+    if (vdev->num_irqs < irq + 1) {
+        error_setg(errp, "vfio: IRQ %u not available (number of irqs %u)",
+                   irq, vdev->num_irqs);
+        return;
+    }
+
+    argsz = sizeof(*irq_info);
+    irq_info = g_malloc0(argsz);
+    irq_info->index = irq;
+    irq_info->argsz = argsz;
+
+    if (ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO,
+              irq_info) < 0 || irq_info->count < 1) {
+        error_setg_errno(errp, errno, "vfio: Error getting irq info");
+        goto out_free_info;
+    }
+
+    if (event_notifier_init(notifier, 0)) {
+        error_setg_errno(errp, errno,
+                         "vfio: Unable to init event notifier for irq (%d)",
+                         irq);
+        goto out_free_info;
+    }
+
+    fd = event_notifier_get_fd(notifier);
+    qemu_set_fd_handler(fd, fd_read, NULL, vapdev);
+
+    if (vfio_set_irq_signaling(vdev, irq, 0, VFIO_IRQ_SET_ACTION_TRIGGER, fd,
+                               errp)) {
+        qemu_set_fd_handler(fd, NULL, NULL, vapdev);
+        event_notifier_cleanup(notifier);
+    }
+
+out_free_info:
+    g_free(irq_info);
+
+}
+
+static void vfio_ap_unregister_irq_notifier(VFIOAPDevice *vapdev,
+                                            unsigned int irq)
+{
+    Error *err = NULL;
+    EventNotifier *notifier;
+
+    switch (irq) {
+    case VFIO_AP_REQ_IRQ_INDEX:
+        notifier = &vapdev->req_notifier;
+        break;
+    default:
+        error_report("vfio: Unsupported device irq(%d)", irq);
+        return;
+    }
+
+    if (vfio_set_irq_signaling(&vapdev->vdev, irq, 0,
+                               VFIO_IRQ_SET_ACTION_TRIGGER, -1, &err)) {
+        warn_reportf_err(err, VFIO_MSG_PREFIX, vapdev->vdev.name);
+    }
+
+    qemu_set_fd_handler(event_notifier_get_fd(notifier),
+                        NULL, NULL, vapdev);
+    event_notifier_cleanup(notifier);
+}
+
 static void vfio_ap_realize(DeviceState *dev, Error **errp)
 {
     int ret;
     char *mdevid;
+    Error *err = NULL;
     VFIOGroup *vfio_group;
     APDevice *apdev = AP_DEVICE(dev);
     VFIOAPDevice *vapdev = VFIO_AP_DEVICE(apdev);
@@ -116,6 +219,15 @@ static void vfio_ap_realize(DeviceState *dev, Error **errp)
         goto out_get_dev_err;
     }
 
+    vfio_ap_register_irq_notifier(vapdev, VFIO_AP_REQ_IRQ_INDEX, &err);
+    if (err) {
+        /*
+         * Report this error, but do not make it a failing condition.
+         * Lack of this IRQ in the host does not prevent normal operation.
+         */
+        error_report_err(err);
+    }
+
     return;
 
 out_get_dev_err:
@@ -129,6 +241,7 @@ static void vfio_ap_unrealize(DeviceState *dev)
     VFIOAPDevice *vapdev = VFIO_AP_DEVICE(apdev);
     VFIOGroup *group = vapdev->vdev.group;
 
+    vfio_ap_unregister_irq_notifier(vapdev, VFIO_AP_REQ_IRQ_INDEX);
     vfio_ap_put_device(vapdev);
     vfio_put_group(group);
 }