virtio-pci: decouple the single vector from the interrupt process

To reuse the interrupt process in configure interrupt
Need to decouple the single vector from the interrupt process. Add new function
kvm_virtio_pci_vector_use_one and _release_one. These functions are use
for the single vector, the whole process will finish in a loop for the vq number.

Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20211104164827.21911-4-lulu@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/virtio-pci.c

@@ -677,7 +677,6 @@ static uint32_t virtio_read_config(PCIDevice *pci_dev,
 }
 
 static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
-                                        unsigned int queue_no,
                                         unsigned int vector)
 {
     VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
@@ -740,30 +739,28 @@ static int virtio_pci_get_notifier(VirtIOPCIProxy *proxy, int queue_no,
     return 0;
 }
 
-static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
+static int kvm_virtio_pci_vector_use_one(VirtIOPCIProxy *proxy, int queue_no)
 {
+    unsigned int vector;
+    int ret;
+    EventNotifier *n;
     PCIDevice *dev = &proxy->pci_dev;
     VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
     VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
-    unsigned int vector;
+
-    int ret, queue_no;
-    EventNotifier *n;
-    for (queue_no = 0; queue_no < nvqs; queue_no++) {
-        if (!virtio_queue_get_num(vdev, queue_no)) {
-            break;
-        }
     ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
     if (ret < 0) {
-            break;
+        return ret;
     }
     if (vector >= msix_nr_vectors_allocated(dev)) {
-            continue;
+        return 0;
     }
-        ret = kvm_virtio_pci_vq_vector_use(proxy, queue_no, vector);
+    ret = kvm_virtio_pci_vq_vector_use(proxy, vector);
     if (ret < 0) {
         goto undo;
     }
-        /* If guest supports masking, set up irqfd now.
+    /*
+     * If guest supports masking, set up irqfd now.
      * Otherwise, delay until unmasked in the frontend.
      */
     if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
@@ -773,55 +770,73 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
             goto undo;
         }
     }
-    }
-    return 0;
 
+    return 0;
 undo:
-    while (--queue_no >= 0) {
+
     vector = virtio_queue_vector(vdev, queue_no);
     if (vector >= msix_nr_vectors_allocated(dev)) {
-            continue;
+        return ret;
     }
     if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
         ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
         if (ret < 0) {
-                break;
+            return ret;
         }
         kvm_virtio_pci_irqfd_release(proxy, n, vector);
     }
-        kvm_virtio_pci_vq_vector_release(proxy, vector);
+    return ret;
+}
+static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
+{
+    int queue_no;
+    int ret = 0;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
+    for (queue_no = 0; queue_no < nvqs; queue_no++) {
+        if (!virtio_queue_get_num(vdev, queue_no)) {
+            return -1;
+        }
+        ret = kvm_virtio_pci_vector_use_one(proxy, queue_no);
     }
     return ret;
 }
 
-static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
+
+static void kvm_virtio_pci_vector_release_one(VirtIOPCIProxy *proxy,
+                                              int queue_no)
 {
-    PCIDevice *dev = &proxy->pci_dev;
     VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
     unsigned int vector;
-    int queue_no;
-    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
     EventNotifier *n;
     int ret;
-    for (queue_no = 0; queue_no < nvqs; queue_no++) {
+    VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
-        if (!virtio_queue_get_num(vdev, queue_no)) {
+    PCIDevice *dev = &proxy->pci_dev;
-            break;
+
-        }
     ret = virtio_pci_get_notifier(proxy, queue_no, &n, &vector);
     if (ret < 0) {
-            break;
+        return;
     }
     if (vector >= msix_nr_vectors_allocated(dev)) {
-            continue;
+        return;
     }
-        /* If guest supports masking, clean up irqfd now.
-         * Otherwise, it was cleaned when masked in the frontend.
-         */
     if (vdev->use_guest_notifier_mask && k->guest_notifier_mask) {
         kvm_virtio_pci_irqfd_release(proxy, n, vector);
     }
     kvm_virtio_pci_vq_vector_release(proxy, vector);
 }
+
+static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
+{
+    int queue_no;
+    VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
+
+    for (queue_no = 0; queue_no < nvqs; queue_no++) {
+        if (!virtio_queue_get_num(vdev, queue_no)) {
+            break;
+        }
+        kvm_virtio_pci_vector_release_one(proxy, queue_no);
+    }
 }
 
 static int virtio_pci_one_vector_unmask(VirtIOPCIProxy *proxy,