1 files changed, 60 insertions, 6 deletions

diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 4e298bc8949d..5a46b8c5d68a 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -32,6 +32,7 @@
  * The pointer to our (page) of device descriptions.
  */
 static void *kvm_devices;
+struct work_struct hotplug_work;
 
 struct kvm_device {
         struct virtio_device vdev;
@@ -328,13 +329,54 @@ static void scan_devices(void)
 }
 
 /*
+ * match for a kvm device with a specific desc pointer
+ */
+static int match_desc(struct device *dev, void *data)
+{
+        if ((ulong)to_kvmdev(dev_to_virtio(dev))->desc == (ulong)data)
+                return 1;
+
+        return 0;
+}
+
+/*
+ * hotplug_device tries to find changes in the device page.
+ */
+static void hotplug_devices(struct work_struct *dummy)
+{
+        unsigned int i;
+        struct kvm_device_desc *d;
+        struct device *dev;
+
+        for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
+                d = kvm_devices + i;
+
+                /* end of list */
+                if (d->type == 0)
+                        break;
+
+                /* device already exists */
+                dev = device_find_child(kvm_root, d, match_desc);
+                if (dev) {
+                        /* XXX check for hotplug remove */
+                        put_device(dev);
+                        continue;
+                }
+
+                /* new device */
+                printk(KERN_INFO "Adding new virtio device %p\n", d);
+                add_kvm_device(d, i);
+        }
+}
+
+/*
  * we emulate the request_irq behaviour on top of s390 extints
  */
 static void kvm_extint_handler(u16 code)
 {
         struct virtqueue *vq;
         u16 subcode;
-        int config_changed;
+        u32 param;
 
         subcode = S390_lowcore.cpu_addr;
         if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
@@ -343,18 +385,28 @@ static void kvm_extint_handler(u16 code)
         /* The LSB might be overloaded, we have to mask it */
         vq = (struct virtqueue *)(S390_lowcore.ext_params2 & ~1UL);
 
-        /* We use the LSB of extparam, to decide, if this interrupt is a config
-         * change or a "standard" interrupt */
-        config_changed = S390_lowcore.ext_params & 1;
+        /* We use ext_params to decide what this interrupt means */
+        param = S390_lowcore.ext_params & VIRTIO_PARAM_MASK;
 
-        if (config_changed) {
+        switch (param) {
+        case VIRTIO_PARAM_CONFIG_CHANGED:
+        {
                 struct virtio_driver *drv;
                 drv = container_of(vq->vdev->dev.driver,
                                    struct virtio_driver, driver);
                 if (drv->config_changed)
                         drv->config_changed(vq->vdev);
-        } else
+
+                break;
+        }
+        case VIRTIO_PARAM_DEV_ADD:
+                schedule_work(&hotplug_work);
+                break;
+        case VIRTIO_PARAM_VRING_INTERRUPT:
+        default:
                 vring_interrupt(0, vq);
+                break;
+        }
 }
 
 /*
@@ -383,6 +435,8 @@ static int __init kvm_devices_init(void)
 
         kvm_devices = (void *) real_memory_size;
 
+        INIT_WORK(&hotplug_work, hotplug_devices);
+
         ctl_set_bit(0, 9);
         register_external_interrupt(0x2603, kvm_extint_handler);