libqos: Added basic virtqueue support to virtio implementation

Add status changing and feature negotiation.
Add basic virtqueue support for adding and sending virtqueue requests.
Add ISR checking.

[Squashed request endianness fix by Greg Kurz <gkurz@linux.vnet.ibm.com>
--Stefan]

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

tests/libqos/virtio.c

@@ -35,6 +35,23 @@ uint64_t qvirtio_config_readq(const QVirtioBus *bus, QVirtioDevice *d,
     return bus->config_readq(d, addr);
 }
 
+uint32_t qvirtio_get_features(const QVirtioBus *bus, QVirtioDevice *d)
+{
+    return bus->get_features(d);
+}
+
+void qvirtio_set_features(const QVirtioBus *bus, QVirtioDevice *d,
+                                                            uint32_t features)
+{
+    bus->set_features(d, features);
+}
+
+QVirtQueue *qvirtqueue_setup(const QVirtioBus *bus, QVirtioDevice *d,
+                                        QGuestAllocator *alloc, uint16_t index)
+{
+    return bus->virtqueue_setup(d, alloc, index);
+}
+
 void qvirtio_reset(const QVirtioBus *bus, QVirtioDevice *d)
 {
     bus->set_status(d, QVIRTIO_RESET);
@@ -53,3 +70,86 @@ void qvirtio_set_driver(const QVirtioBus *bus, QVirtioDevice *d)
     g_assert_cmphex(bus->get_status(d), ==,
                                     QVIRTIO_DRIVER | QVIRTIO_ACKNOWLEDGE);
 }
+
+void qvirtio_set_driver_ok(const QVirtioBus *bus, QVirtioDevice *d)
+{
+    bus->set_status(d, bus->get_status(d) | QVIRTIO_DRIVER_OK);
+    g_assert_cmphex(bus->get_status(d), ==,
+                QVIRTIO_DRIVER_OK | QVIRTIO_DRIVER | QVIRTIO_ACKNOWLEDGE);
+}
+
+bool qvirtio_wait_isr(const QVirtioBus *bus, QVirtioDevice *d, uint8_t mask,
+                                                            uint64_t timeout)
+{
+    do {
+        clock_step(10);
+        if (bus->get_isr_status(d) & mask) {
+            break; /* It has ended */
+        }
+    } while (--timeout);
+
+    return timeout != 0;
+}
+
+void qvring_init(const QGuestAllocator *alloc, QVirtQueue *vq, uint64_t addr)
+{
+    int i;
+
+    vq->desc = addr;
+    vq->avail = vq->desc + vq->size*sizeof(QVRingDesc);
+    vq->used = (uint64_t)((vq->avail + sizeof(uint16_t) * (3 + vq->size)
+        + vq->align - 1) & ~(vq->align - 1));
+
+    for (i = 0; i < vq->size - 1; i++) {
+        /* vq->desc[i].addr */
+        writew(vq->desc + (16 * i), 0);
+        /* vq->desc[i].next */
+        writew(vq->desc + (16 * i) + 14, i + 1);
+    }
+
+    /* vq->avail->flags */
+    writew(vq->avail, 0);
+    /* vq->avail->idx */
+    writew(vq->avail + 2, 0);
+
+    /* vq->used->flags */
+    writew(vq->used, 0);
+}
+
+uint32_t qvirtqueue_add(QVirtQueue *vq, uint64_t data, uint32_t len, bool write,
+                                                                    bool next)
+{
+    uint16_t flags = 0;
+    vq->num_free--;
+
+    if (write) {
+        flags |= QVRING_DESC_F_WRITE;
+    }
+
+    if (next) {
+        flags |= QVRING_DESC_F_NEXT;
+    }
+
+    /* vq->desc[vq->free_head].addr */
+    writeq(vq->desc + (16 * vq->free_head), data);
+    /* vq->desc[vq->free_head].len */
+    writel(vq->desc + (16 * vq->free_head) + 8, len);
+    /* vq->desc[vq->free_head].flags */
+    writew(vq->desc + (16 * vq->free_head) + 12, flags);
+
+    return vq->free_head++; /* Return and increase, in this order */
+}
+
+void qvirtqueue_kick(const QVirtioBus *bus, QVirtioDevice *d, QVirtQueue *vq,
+                                                            uint32_t free_head)
+{
+    /* vq->avail->idx */
+    uint16_t idx = readl(vq->avail + 2);
+
+    /* vq->avail->ring[idx % vq->size] */
+    writel(vq->avail + 4 + (2 * (idx % vq->size)), free_head);
+    /* vq->avail->idx */
+    writel(vq->avail + 2, idx + 1);
+
+    bus->virtqueue_kick(d, vq);
+}