virtio: move allocation to virtqueue_pop/vring_pop

The return code of virtqueue_pop/vring_pop is unused except to check for
errors or 0.  We can thus easily move allocation inside the functions
and just return a pointer to the VirtQueueElement.

The advantage is that we will be able to allocate only the space that
is needed for the actual size of the s/g list instead of the full
VIRTQUEUE_MAX_SIZE items.  Currently VirtQueueElement takes about 48K
of memory, and this kind of allocation puts a lot of stress on malloc.
By cutting the size by two or three orders of magnitude, malloc can
use much more efficient algorithms.

The patch is pretty large, but changes to each device are testable
more or less independently.  Splitting it would mostly add churn.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 15fb0ab75d8e38869d2a79ba8d35a8f1ea7975f7..db5f4780dcd130347c27db65df05fb615d85f03a 100644 (file)
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1587,7 +1587,7 @@ static int v9fs_xattr_read(V9fsState *s, V9fsPDU *pdu, V9fsFidState *fidp,
     int read_count;
     int64_t xattr_len;
     V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
-    VirtQueueElement *elem = &v->elems[pdu->idx];
+    VirtQueueElement *elem = v->elems[pdu->idx];
 
     xattr_len = fidp->fs.xattr.len;
     read_count = xattr_len - off;

diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index c5f7b926403e698169c0acdbc16ea9ca46033477..a38850ee89dad867cfe5b2e7dddde04bf65f4acb 100644 (file)
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -26,10 +26,12 @@ void virtio_9p_push_and_notify(V9fsPDU *pdu)
 {
     V9fsState *s = pdu->s;
     V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
-    VirtQueueElement *elem = &v->elems[pdu->idx];
+    VirtQueueElement *elem = v->elems[pdu->idx];
 
     /* push onto queue and notify */
     virtqueue_push(v->vq, elem, pdu->size);
+    g_free(elem);
+    v->elems[pdu->idx] = NULL;
 
     /* FIXME: we should batch these completions */
     virtio_notify(VIRTIO_DEVICE(v), v->vq);
@@ -48,10 +50,10 @@ static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq)
             uint8_t id;
             uint16_t tag_le;
         } QEMU_PACKED out;
-        VirtQueueElement *elem = &v->elems[pdu->idx];
+        VirtQueueElement *elem;
 
-        len = virtqueue_pop(vq, elem);
-        if (!len) {
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
             pdu_free(pdu);
             break;
         }
@@ -59,6 +61,7 @@ static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq)
         BUG_ON(elem->out_num == 0 || elem->in_num == 0);
         QEMU_BUILD_BUG_ON(sizeof out != 7);
 
+        v->elems[pdu->idx] = elem;
         len = iov_to_buf(elem->out_sg, elem->out_num, 0,
                          &out, sizeof out);
         BUG_ON(len != sizeof out);
@@ -141,7 +144,7 @@ ssize_t virtio_pdu_vmarshal(V9fsPDU *pdu, size_t offset,
 {
     V9fsState *s = pdu->s;
     V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
-    VirtQueueElement *elem = &v->elems[pdu->idx];
+    VirtQueueElement *elem = v->elems[pdu->idx];
 
     return v9fs_iov_vmarshal(elem->in_sg, elem->in_num, offset, 1, fmt, ap);
 }
@@ -151,7 +154,7 @@ ssize_t virtio_pdu_vunmarshal(V9fsPDU *pdu, size_t offset,
 {
     V9fsState *s = pdu->s;
     V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
-    VirtQueueElement *elem = &v->elems[pdu->idx];
+    VirtQueueElement *elem = v->elems[pdu->idx];
 
     return v9fs_iov_vunmarshal(elem->out_sg, elem->out_num, offset, 1, fmt, ap);
 }
@@ -161,7 +164,7 @@ void virtio_init_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
 {
     V9fsState *s = pdu->s;
     V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
-    VirtQueueElement *elem = &v->elems[pdu->idx];
+    VirtQueueElement *elem = v->elems[pdu->idx];
 
     if (is_write) {
         *piov = elem->out_sg;

diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index 1cdf0a2d652946b76d1a2637541a2e86a649ae9f..7f6d88553937e4b28fb199eba3bf0525009bac26 100644 (file)
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -11,7 +11,7 @@ typedef struct V9fsVirtioState
     VirtQueue *vq;
     size_t config_size;
     V9fsPDU pdus[MAX_REQ];
-    VirtQueueElement elems[MAX_REQ];
+    VirtQueueElement *elems[MAX_REQ];
     V9fsState state;
 } V9fsVirtioState;
 

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index ee0c4d4070080128ddc6cade014981565a2a640e..0d9978109cb86dd57ba8bfdfe6f2ed1307233f5e 100644 (file)
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -100,20 +100,19 @@ static void handle_notify(EventNotifier *e)
     blk_io_plug(s->conf->conf.blk);
     for (;;) {
         MultiReqBuffer mrb = {};
-        int ret;
 
         /* Disable guest->host notifies to avoid unnecessary vmexits */
         vring_disable_notification(s->vdev, &s->vring);
 
         for (;;) {
-            VirtIOBlockReq *req = virtio_blk_alloc_request(vblk);
+            VirtIOBlockReq *req = vring_pop(s->vdev, &s->vring,
+                                            sizeof(VirtIOBlockReq));
 
-            ret = vring_pop(s->vdev, &s->vring, &req->elem);
-            if (ret < 0) {
-                virtio_blk_free_request(req);
+            if (req == NULL) {
                 break; /* no more requests */
             }
 
+            virtio_blk_init_request(vblk, req);
             trace_virtio_blk_data_plane_process_request(s, req->elem.out_num,
                                                         req->elem.in_num,
                                                         req->elem.index);
@@ -125,7 +124,7 @@ static void handle_notify(EventNotifier *e)
             virtio_blk_submit_multireq(s->conf->conf.blk, &mrb);
         }
 
-        if (likely(ret == -EAGAIN)) { /* vring emptied */
+        if (likely(!vring_more_avail(s->vdev, &s->vring))) { /* vring emptied */
             /* Re-enable guest->host notifies and stop processing the vring.
              * But if the guest has snuck in more descriptors, keep processing.
              */

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 11bedff6d6793766f283b3e9bcc64a4ad1ce0120..bf70b52dfdf41a1aec31bb56befea0bb1ec701c8 100644 (file)
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -29,15 +29,13 @@
 #include "hw/virtio/virtio-bus.h"
 #include "hw/virtio/virtio-access.h"
 
-VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
+void virtio_blk_init_request(VirtIOBlock *s, VirtIOBlockReq *req)
 {
-    VirtIOBlockReq *req = g_new(VirtIOBlockReq, 1);
     req->dev = s;
     req->qiov.size = 0;
     req->in_len = 0;
     req->next = NULL;
     req->mr_next = NULL;
-    return req;
 }
 
 void virtio_blk_free_request(VirtIOBlockReq *req)
@@ -193,13 +191,11 @@ out:
 
 static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
 {
-    VirtIOBlockReq *req = virtio_blk_alloc_request(s);
+    VirtIOBlockReq *req = virtqueue_pop(s->vq, sizeof(VirtIOBlockReq));
 
-    if (!virtqueue_pop(s->vq, &req->elem)) {
-        virtio_blk_free_request(req);
-        return NULL;
+    if (req) {
+        virtio_blk_init_request(s, req);
     }
-
     return req;
 }
 
@@ -836,7 +832,8 @@ static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
     VirtIOBlock *s = VIRTIO_BLK(vdev);
 
     while (qemu_get_sbyte(f)) {
-        VirtIOBlockReq *req = virtio_blk_alloc_request(s);
+        VirtIOBlockReq *req = g_new(VirtIOBlockReq, 1);
+        virtio_blk_init_request(s, req);
         qemu_get_buffer(f, (unsigned char *)&req->elem,
                         sizeof(VirtQueueElement));
         req->next = s->rq;

diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 8d5c740558e819415d46f595569ce88abb763ae4..cf3d12b9d579eee478d660344454607088422dc7 100644 (file)
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -83,7 +83,7 @@ static bool use_multiport(VirtIOSerial *vser)
 static size_t write_to_port(VirtIOSerialPort *port,
                             const uint8_t *buf, size_t size)
 {
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     VirtQueue *vq;
     size_t offset;
 
@@ -96,15 +96,17 @@ static size_t write_to_port(VirtIOSerialPort *port,
     while (offset < size) {
         size_t len;
 
-        if (!virtqueue_pop(vq, &elem)) {
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
             break;
         }
 
-        len = iov_from_buf(elem.in_sg, elem.in_num, 0,
+        len = iov_from_buf(elem->in_sg, elem->in_num, 0,
                            buf + offset, size - offset);
         offset += len;
 
-        virtqueue_push(vq, &elem, len);
+        virtqueue_push(vq, elem, len);
+        g_free(elem);
     }
 
     virtio_notify(VIRTIO_DEVICE(port->vser), vq);
@@ -113,13 +115,18 @@ static size_t write_to_port(VirtIOSerialPort *port,
 
 static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev)
 {
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
 
     if (!virtio_queue_ready(vq)) {
         return;
     }
-    while (virtqueue_pop(vq, &elem)) {
-        virtqueue_push(vq, &elem, 0);
+    for (;;) {
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
+            break;
+        }
+        virtqueue_push(vq, elem, 0);
+        g_free(elem);
     }
     virtio_notify(vdev, vq);
 }
@@ -138,21 +145,22 @@ static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
         unsigned int i;
 
         /* Pop an elem only if we haven't left off a previous one mid-way */
-        if (!port->elem.out_num) {
-            if (!virtqueue_pop(vq, &port->elem)) {
+        if (!port->elem) {
+            port->elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+            if (!port->elem) {
                 break;
             }
             port->iov_idx = 0;
             port->iov_offset = 0;
         }
 
-        for (i = port->iov_idx; i < port->elem.out_num; i++) {
+        for (i = port->iov_idx; i < port->elem->out_num; i++) {
             size_t buf_size;
             ssize_t ret;
 
-            buf_size = port->elem.out_sg[i].iov_len - port->iov_offset;
+            buf_size = port->elem->out_sg[i].iov_len - port->iov_offset;
             ret = vsc->have_data(port,
-                                  port->elem.out_sg[i].iov_base
+                                  port->elem->out_sg[i].iov_base
                                   + port->iov_offset,
                                   buf_size);
             if (port->throttled) {
@@ -167,8 +175,9 @@ static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
         if (port->throttled) {
             break;
         }
-        virtqueue_push(vq, &port->elem, 0);
-        port->elem.out_num = 0;
+        virtqueue_push(vq, port->elem, 0);
+        g_free(port->elem);
+        port->elem = NULL;
     }
     virtio_notify(vdev, vq);
 }
@@ -185,22 +194,26 @@ static void flush_queued_data(VirtIOSerialPort *port)
 
 static size_t send_control_msg(VirtIOSerial *vser, void *buf, size_t len)
 {
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     VirtQueue *vq;
 
     vq = vser->c_ivq;
     if (!virtio_queue_ready(vq)) {
         return 0;
     }
-    if (!virtqueue_pop(vq, &elem)) {
+
+    elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+    if (!elem) {
         return 0;
     }
 
     /* TODO: detect a buffer that's too short, set NEEDS_RESET */
-    iov_from_buf(elem.in_sg, elem.in_num, 0, buf, len);
+    iov_from_buf(elem->in_sg, elem->in_num, 0, buf, len);
 
-    virtqueue_push(vq, &elem, len);
+    virtqueue_push(vq, elem, len);
     virtio_notify(VIRTIO_DEVICE(vser), vq);
+    g_free(elem);
+
     return len;
 }
 
@@ -414,7 +427,7 @@ static void control_in(VirtIODevice *vdev, VirtQueue *vq)
 
 static void control_out(VirtIODevice *vdev, VirtQueue *vq)
 {
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     VirtIOSerial *vser;
     uint8_t *buf;
     size_t len;
@@ -423,10 +436,15 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq)
 
     len = 0;
     buf = NULL;
-    while (virtqueue_pop(vq, &elem)) {
+    for (;;) {
         size_t cur_len;
 
-        cur_len = iov_size(elem.out_sg, elem.out_num);
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
+            break;
+        }
+
+        cur_len = iov_size(elem->out_sg, elem->out_num);
         /*
          * Allocate a new buf only if we didn't have one previously or
          * if the size of the buf differs
@@ -437,10 +455,11 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq)
             buf = g_malloc(cur_len);
             len = cur_len;
         }
-        iov_to_buf(elem.out_sg, elem.out_num, 0, buf, cur_len);
+        iov_to_buf(elem->out_sg, elem->out_num, 0, buf, cur_len);
 
         handle_control_message(vser, buf, cur_len);
-        virtqueue_push(vq, &elem, 0);
+        virtqueue_push(vq, elem, 0);
+        g_free(elem);
     }
     g_free(buf);
     virtio_notify(vdev, vq);
@@ -620,7 +639,7 @@ static void virtio_serial_save_device(VirtIODevice *vdev, QEMUFile *f)
         qemu_put_byte(f, port->host_connected);
 
        elem_popped = 0;
-        if (port->elem.out_num) {
+        if (port->elem) {
             elem_popped = 1;
         }
         qemu_put_be32s(f, &elem_popped);
@@ -628,8 +647,8 @@ static void virtio_serial_save_device(VirtIODevice *vdev, QEMUFile *f)
             qemu_put_be32s(f, &port->iov_idx);
             qemu_put_be64s(f, &port->iov_offset);
 
-            qemu_put_buffer(f, (unsigned char *)&port->elem,
-                            sizeof(port->elem));
+            qemu_put_buffer(f, (unsigned char *)port->elem,
+                            sizeof(VirtQueueElement));
         }
     }
 }
@@ -704,9 +723,10 @@ static int fetch_active_ports_list(QEMUFile *f, int version_id,
                 qemu_get_be32s(f, &port->iov_idx);
                 qemu_get_be64s(f, &port->iov_offset);
 
-                qemu_get_buffer(f, (unsigned char *)&port->elem,
-                                sizeof(port->elem));
-                virtqueue_map(&port->elem);
+                port->elem = g_new(VirtQueueElement, 1);
+                qemu_get_buffer(f, (unsigned char *)port->elem,
+                                sizeof(VirtQueueElement));
+                virtqueue_map(port->elem);
 
                 /*
                  *  Port was throttled on source machine.  Let's
@@ -928,7 +948,7 @@ static void virtser_port_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    port->elem.out_num = 0;
+    port->elem = NULL;
 }
 
 static void virtser_port_device_plug(HotplugHandler *hotplug_dev,

diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 1cb4002e0e5355d6ac3ec8fa39bcfefe5465ab4e..ddf3bfbef49dceae0fa55054646de685aeda1592 100644 (file)
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -804,16 +804,15 @@ static void virtio_gpu_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
     }
 #endif
 
-    cmd = g_new(struct virtio_gpu_ctrl_command, 1);
-    while (virtqueue_pop(vq, &cmd->elem)) {
+    cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
+    while (cmd) {
         cmd->vq = vq;
         cmd->error = 0;
         cmd->finished = false;
         cmd->waiting = false;
         QTAILQ_INSERT_TAIL(&g->cmdq, cmd, next);
-        cmd = g_new(struct virtio_gpu_ctrl_command, 1);
+        cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
     }
-    g_free(cmd);
 
     virtio_gpu_process_cmdq(g);
 
@@ -833,15 +832,20 @@ static void virtio_gpu_ctrl_bh(void *opaque)
 static void virtio_gpu_handle_cursor(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOGPU *g = VIRTIO_GPU(vdev);
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     size_t s;
     struct virtio_gpu_update_cursor cursor_info;
 
     if (!virtio_queue_ready(vq)) {
         return;
     }
-    while (virtqueue_pop(vq, &elem)) {
-        s = iov_to_buf(elem.out_sg, elem.out_num, 0,
+    for (;;) {
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
+            break;
+        }
+
+        s = iov_to_buf(elem->out_sg, elem->out_num, 0,
                        &cursor_info, sizeof(cursor_info));
         if (s != sizeof(cursor_info)) {
             qemu_log_mask(LOG_GUEST_ERROR,
@@ -850,8 +854,9 @@ static void virtio_gpu_handle_cursor(VirtIODevice *vdev, VirtQueue *vq)
         } else {
             update_cursor(g, &cursor_info);
         }
-        virtqueue_push(vq, &elem, 0);
+        virtqueue_push(vq, elem, 0);
         virtio_notify(vdev, vq);
+        g_free(elem);
     }
 }
 

diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c
index f12ed8a50476f7ddfef6ba63bebf2dbfae1245cc..5061f4cf7acbeef415e6b1056ae70884aeaf26ad 100644 (file)
--- a/hw/input/virtio-input.c
+++ b/hw/input/virtio-input.c
@@ -17,7 +17,7 @@
 
 void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event)
 {
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     unsigned have, need;
     int i, len;
 
@@ -50,14 +50,16 @@ void virtio_input_send(VirtIOInput *vinput, virtio_input_event *event)
 
     /* ... and finally pass them to the guest */
     for (i = 0; i < vinput->qindex; i++) {
-        if (!virtqueue_pop(vinput->evt, &elem)) {
+        elem = virtqueue_pop(vinput->evt, sizeof(VirtQueueElement));
+        if (!elem) {
             /* should not happen, we've checked for space beforehand */
             fprintf(stderr, "%s: Huh?  No vq elem available ...\n", __func__);
             return;
         }
-        len = iov_from_buf(elem.in_sg, elem.in_num,
+        len = iov_from_buf(elem->in_sg, elem->in_num,
                            0, vinput->queue+i, sizeof(virtio_input_event));
-        virtqueue_push(vinput->evt, &elem, len);
+        virtqueue_push(vinput->evt, elem, len);
+        g_free(elem);
     }
     virtio_notify(VIRTIO_DEVICE(vinput), vinput->evt);
     vinput->qindex = 0;
@@ -73,17 +75,23 @@ static void virtio_input_handle_sts(VirtIODevice *vdev, VirtQueue *vq)
     VirtIOInputClass *vic = VIRTIO_INPUT_GET_CLASS(vdev);
     VirtIOInput *vinput = VIRTIO_INPUT(vdev);
     virtio_input_event event;
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     int len;
 
-    while (virtqueue_pop(vinput->sts, &elem)) {
+    for (;;) {
+        elem = virtqueue_pop(vinput->sts, sizeof(VirtQueueElement));
+        if (!elem) {
+            break;
+        }
+
         memset(&event, 0, sizeof(event));
-        len = iov_to_buf(elem.out_sg, elem.out_num,
+        len = iov_to_buf(elem->out_sg, elem->out_num,
                          0, &event, sizeof(event));
         if (vic->handle_status) {
             vic->handle_status(vinput, &event);
         }
-        virtqueue_push(vinput->sts, &elem, len);
+        virtqueue_push(vinput->sts, elem, len);
+        g_free(elem);
     }
     virtio_notify(vdev, vinput->sts);
 }

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index fde8dd3157df170f4c08776cd166db55ad547d68..de696e8dd0d6eb5667193b3c523f7f22533e20ef 100644 (file)
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -819,20 +819,24 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
     VirtIONet *n = VIRTIO_NET(vdev);
     struct virtio_net_ctrl_hdr ctrl;
     virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     size_t s;
     struct iovec *iov, *iov2;
     unsigned int iov_cnt;
 
-    while (virtqueue_pop(vq, &elem)) {
-        if (iov_size(elem.in_sg, elem.in_num) < sizeof(status) ||
-            iov_size(elem.out_sg, elem.out_num) < sizeof(ctrl)) {
+    for (;;) {
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
+            break;
+        }
+        if (iov_size(elem->in_sg, elem->in_num) < sizeof(status) ||
+            iov_size(elem->out_sg, elem->out_num) < sizeof(ctrl)) {
             error_report("virtio-net ctrl missing headers");
             exit(1);
         }
 
-        iov_cnt = elem.out_num;
-        iov2 = iov = g_memdup(elem.out_sg, sizeof(struct iovec) * elem.out_num);
+        iov_cnt = elem->out_num;
+        iov2 = iov = g_memdup(elem->out_sg, sizeof(struct iovec) * elem->out_num);
         s = iov_to_buf(iov, iov_cnt, 0, &ctrl, sizeof(ctrl));
         iov_discard_front(&iov, &iov_cnt, sizeof(ctrl));
         if (s != sizeof(ctrl)) {
@@ -851,12 +855,13 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
             status = virtio_net_handle_offloads(n, ctrl.cmd, iov, iov_cnt);
         }
 
-        s = iov_from_buf(elem.in_sg, elem.in_num, 0, &status, sizeof(status));
+        s = iov_from_buf(elem->in_sg, elem->in_num, 0, &status, sizeof(status));
         assert(s == sizeof(status));
 
-        virtqueue_push(vq, &elem, sizeof(status));
+        virtqueue_push(vq, elem, sizeof(status));
         virtio_notify(vdev, vq);
         g_free(iov2);
+        g_free(elem);
     }
 }
 
@@ -1045,13 +1050,14 @@ static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
     offset = i = 0;
 
     while (offset < size) {
-        VirtQueueElement elem;
+        VirtQueueElement *elem;
         int len, total;
-        const struct iovec *sg = elem.in_sg;
+        const struct iovec *sg;
 
         total = 0;
 
-        if (virtqueue_pop(q->rx_vq, &elem) == 0) {
+        elem = virtqueue_pop(q->rx_vq, sizeof(VirtQueueElement));
+        if (!elem) {
             if (i == 0)
                 return -1;
             error_report("virtio-net unexpected empty queue: "
@@ -1064,21 +1070,22 @@ static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
             exit(1);
         }
 
-        if (elem.in_num < 1) {
+        if (elem->in_num < 1) {
             error_report("virtio-net receive queue contains no in buffers");
             exit(1);
         }
 
+        sg = elem->in_sg;
         if (i == 0) {
             assert(offset == 0);
             if (n->mergeable_rx_bufs) {
                 mhdr_cnt = iov_copy(mhdr_sg, ARRAY_SIZE(mhdr_sg),
-                                    sg, elem.in_num,
+                                    sg, elem->in_num,
                                     offsetof(typeof(mhdr), num_buffers),
                                     sizeof(mhdr.num_buffers));
             }
 
-            receive_header(n, sg, elem.in_num, buf, size);
+            receive_header(n, sg, elem->in_num, buf, size);
             offset = n->host_hdr_len;
             total += n->guest_hdr_len;
             guest_offset = n->guest_hdr_len;
@@ -1087,7 +1094,7 @@ static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
         }
 
         /* copy in packet.  ugh */
-        len = iov_from_buf(sg, elem.in_num, guest_offset,
+        len = iov_from_buf(sg, elem->in_num, guest_offset,
                            buf + offset, size - offset);
         total += len;
         offset += len;
@@ -1095,12 +1102,14 @@ static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
          * must have consumed the complete packet.
          * Otherwise, drop it. */
         if (!n->mergeable_rx_bufs && offset < size) {
-            virtqueue_discard(q->rx_vq, &elem, total);
+            virtqueue_discard(q->rx_vq, elem, total);
+            g_free(elem);
             return size;
         }
 
         /* signal other side */
-        virtqueue_fill(q->rx_vq, &elem, total, i++);
+        virtqueue_fill(q->rx_vq, elem, total, i++);
+        g_free(elem);
     }
 
     if (mhdr_cnt) {
@@ -1124,10 +1133,11 @@ static void virtio_net_tx_complete(NetClientState *nc, ssize_t len)
     VirtIONetQueue *q = virtio_net_get_subqueue(nc);
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
 
-    virtqueue_push(q->tx_vq, &q->async_tx.elem, 0);
+    virtqueue_push(q->tx_vq, q->async_tx.elem, 0);
     virtio_notify(vdev, q->tx_vq);
 
-    q->async_tx.elem.out_num = 0;
+    g_free(q->async_tx.elem);
+    q->async_tx.elem = NULL;
 
     virtio_queue_set_notification(q->tx_vq, 1);
     virtio_net_flush_tx(q);
@@ -1138,25 +1148,31 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
 {
     VirtIONet *n = q->n;
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     int32_t num_packets = 0;
     int queue_index = vq2q(virtio_get_queue_index(q->tx_vq));
     if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return num_packets;
     }
 
-    if (q->async_tx.elem.out_num) {
+    if (q->async_tx.elem) {
         virtio_queue_set_notification(q->tx_vq, 0);
         return num_packets;
     }
 
-    while (virtqueue_pop(q->tx_vq, &elem)) {
+    for (;;) {
         ssize_t ret;
-        unsigned int out_num = elem.out_num;
-        struct iovec *out_sg = &elem.out_sg[0];
-        struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE + 1];
+        unsigned int out_num;
+        struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE + 1], *out_sg;
         struct virtio_net_hdr_mrg_rxbuf mhdr;
 
+        elem = virtqueue_pop(q->tx_vq, sizeof(VirtQueueElement));
+        if (!elem) {
+            break;
+        }
+
+        out_num = elem->out_num;
+        out_sg = elem->out_sg;
         if (out_num < 1) {
             error_report("virtio-net header not in first element");
             exit(1);
@@ -1208,8 +1224,9 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
         }
 
 drop:
-        virtqueue_push(q->tx_vq, &elem, 0);
+        virtqueue_push(q->tx_vq, elem, 0);
         virtio_notify(vdev, q->tx_vq);
+        g_free(elem);
 
         if (++num_packets >= n->tx_burst) {
             break;

diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index c77b3a1058c6081963a7416f9e3494b00268094f..8340326a501aeb7f9cbcf261fa274ed62830d033 100644 (file)
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -81,15 +81,16 @@ fail_vring:
 VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
                                          VirtIOSCSIVring *vring)
 {
-    VirtIOSCSIReq *req = virtio_scsi_init_req(s, NULL);
-    int r;
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
+    VirtIOSCSIReq *req;
 
-    req->vring = vring;
-    r = vring_pop((VirtIODevice *)s, &vring->vring, &req->elem);
-    if (r < 0) {
-        virtio_scsi_free_req(req);
-        req = NULL;
+    req = vring_pop((VirtIODevice *)s, &vring->vring,
+                    sizeof(VirtIOSCSIReq) + vs->cdb_size);
+    if (!req) {
+        return NULL;
     }
+    virtio_scsi_init_req(s, NULL, req);
+    req->vring = vring;
     return req;
 }
 

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 7fdf6ade98cc333574329616f174db2df32c81fd..50a3cb28b5b165454a443000b43a0ce0241dc629 100644 (file)
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -41,19 +41,15 @@ static inline SCSIDevice *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
     return scsi_device_find(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
 }
 
-VirtIOSCSIReq *virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq)
+void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
 {
-    VirtIOSCSIReq *req;
-    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
     const size_t zero_skip = offsetof(VirtIOSCSIReq, vring);
 
-    req = g_malloc(sizeof(*req) + vs->cdb_size);
     req->vq = vq;
     req->dev = s;
     qemu_sglist_init(&req->qsgl, DEVICE(s), 8, &address_space_memory);
     qemu_iovec_init(&req->resp_iov, 1);
     memset((uint8_t *)req + zero_skip, 0, sizeof(*req) - zero_skip);
-    return req;
 }
 
 void virtio_scsi_free_req(VirtIOSCSIReq *req)
@@ -174,11 +170,14 @@ static int virtio_scsi_parse_req(VirtIOSCSIReq *req,
 
 static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq)
 {
-    VirtIOSCSIReq *req = virtio_scsi_init_req(s, vq);
-    if (!virtqueue_pop(vq, &req->elem)) {
-        virtio_scsi_free_req(req);
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
+    VirtIOSCSIReq *req;
+
+    req = virtqueue_pop(vq, sizeof(VirtIOSCSIReq) + vs->cdb_size);
+    if (!req) {
         return NULL;
     }
+    virtio_scsi_init_req(s, vq, req);
     return req;
 }
 
@@ -203,8 +202,9 @@ static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
 
     qemu_get_be32s(f, &n);
     assert(n < vs->conf.num_queues);
-    req = virtio_scsi_init_req(s, vs->cmd_vqs[n]);
+    req = g_malloc(sizeof(VirtIOSCSIReq) + vs->cdb_size);
     qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));
+    virtio_scsi_init_req(s, vs->cmd_vqs[n], req);
 
     virtqueue_map(&req->elem);
 

diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c
index 1a78df10fa20a085e8119ddfcd19a4a79c50fc69..4fb84bb00a9c9a115a8e2afbdb9a3e95a59ba466 100644 (file)
--- a/hw/virtio/dataplane/vring.c
+++ b/hw/virtio/dataplane/vring.c
@@ -389,23 +389,26 @@ static void vring_unmap_element(VirtQueueElement *elem)
  *
  * Stolen from linux/drivers/vhost/vhost.c.
  */
-int vring_pop(VirtIODevice *vdev, Vring *vring,
-              VirtQueueElement *elem)
+void *vring_pop(VirtIODevice *vdev, Vring *vring, size_t sz)
 {
     struct vring_desc desc;
     unsigned int i, head, found = 0, num = vring->vr.num;
     uint16_t avail_idx, last_avail_idx;
+    VirtQueueElement *elem = NULL;
     int ret;
 
-    /* Initialize elem so it can be safely unmapped */
-    elem->in_num = elem->out_num = 0;
-
     /* If there was a fatal error then refuse operation */
     if (vring->broken) {
         ret = -EFAULT;
         goto out;
     }
 
+    assert(sz >= sizeof(VirtQueueElement));
+    elem = g_malloc(sz);
+
+    /* Initialize elem so it can be safely unmapped */
+    elem->in_num = elem->out_num = 0;
+
     /* Check it isn't doing very strange things with descriptor numbers. */
     last_avail_idx = vring->last_avail_idx;
     avail_idx = vring_get_avail_idx(vdev, vring);
@@ -481,7 +484,7 @@ int vring_pop(VirtIODevice *vdev, Vring *vring,
             virtio_tswap16(vdev, vring->last_avail_idx);
     }
 
-    return head;
+    return elem;
 
 out:
     assert(ret < 0);
@@ -489,7 +492,8 @@ out:
         vring->broken = true;
     }
     vring_unmap_element(elem);
-    return ret;
+    g_free(elem);
+    return NULL;
 }
 
 /* After we've used one of their buffers, we tell them about it.

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index f5f25a95fce0c33647eaec6e8086e51dfe9df315..5c3020331cbeb6c37d99cf4559e198c58c101f55 100644 (file)
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -107,8 +107,10 @@ static void balloon_stats_poll_cb(void *opaque)
         return;
     }
 
-    virtqueue_push(s->svq, &s->stats_vq_elem, s->stats_vq_offset);
+    virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
     virtio_notify(vdev, s->svq);
+    g_free(s->stats_vq_elem);
+    s->stats_vq_elem = NULL;
 }
 
 static void balloon_stats_get_all(Object *obj, struct Visitor *v,
@@ -206,14 +208,18 @@ static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
 static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     MemoryRegionSection section;
 
-    while (virtqueue_pop(vq, &elem)) {
+    for (;;) {
         size_t offset = 0;
         uint32_t pfn;
+        elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+        if (!elem) {
+            return;
+        }
 
-        while (iov_to_buf(elem.out_sg, elem.out_num, offset, &pfn, 4) == 4) {
+        while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
             ram_addr_t pa;
             ram_addr_t addr;
             int p = virtio_ldl_p(vdev, &pfn);
@@ -236,20 +242,22 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
             memory_region_unref(section.mr);
         }
 
-        virtqueue_push(vq, &elem, offset);
+        virtqueue_push(vq, elem, offset);
         virtio_notify(vdev, vq);
+        g_free(elem);
     }
 }
 
 static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
-    VirtQueueElement *elem = &s->stats_vq_elem;
+    VirtQueueElement *elem;
     VirtIOBalloonStat stat;
     size_t offset = 0;
     qemu_timeval tv;
 
-    if (!virtqueue_pop(vq, elem)) {
+    s->stats_vq_elem = elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+    if (!elem) {
         goto out;
     }
 

diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index a80fb89069e747309f2299b228a60a93ab288203..17da2f8f3d6587028c9ef7fe4f2585b56b827907 100644 (file)
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -44,7 +44,7 @@ static void chr_read(void *opaque, const void *buf, size_t size)
 {
     VirtIORNG *vrng = opaque;
     VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
     size_t len;
     int offset;
 
@@ -56,15 +56,17 @@ static void chr_read(void *opaque, const void *buf, size_t size)
 
     offset = 0;
     while (offset < size) {
-        if (!virtqueue_pop(vrng->vq, &elem)) {
+        elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement));
+        if (!elem) {
             break;
         }
-        len = iov_from_buf(elem.in_sg, elem.in_num,
+        len = iov_from_buf(elem->in_sg, elem->in_num,
                            0, buf + offset, size - offset);
         offset += len;
 
-        virtqueue_push(vrng->vq, &elem, len);
+        virtqueue_push(vrng->vq, elem, len);
         trace_virtio_rng_pushed(vrng, len);
+        g_free(elem);
     }
     virtio_notify(vdev, vrng->vq);
 }

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 0603793e34e956311a0181980e6e8fa6fcc92cea..229a092c832579a894becff15a4d25a278be0ece 100644 (file)
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -501,16 +501,20 @@ void virtqueue_map(VirtQueueElement *elem)
                         0);
 }
 
-int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
+void *virtqueue_pop(VirtQueue *vq, size_t sz)
 {
     unsigned int i, head, max;
     hwaddr desc_pa = vq->vring.desc;
     VirtIODevice *vdev = vq->vdev;
+    VirtQueueElement *elem;
 
-    if (!virtqueue_num_heads(vq, vq->last_avail_idx))
-        return 0;
+    if (!virtqueue_num_heads(vq, vq->last_avail_idx)) {
+        return NULL;
+    }
 
     /* When we start there are none of either input nor output. */
+    assert(sz >= sizeof(VirtQueueElement));
+    elem = g_malloc(sz);
     elem->out_num = elem->in_num = 0;
 
     max = vq->vring.num;
@@ -569,7 +573,7 @@ int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
     vq->inuse++;
 
     trace_virtqueue_pop(vq, elem, elem->in_num, elem->out_num);
-    return elem->in_num + elem->out_num;
+    return elem;
 }
 
 /* virtio device */

diff --git a/include/hw/virtio/dataplane/vring.h b/include/hw/virtio/dataplane/vring.h
index a596e4c17541d15474a2113eafbb15add277f540..e80985ee4c88013c190159d1f240cef9a8b63065 100644 (file)
--- a/include/hw/virtio/dataplane/vring.h
+++ b/include/hw/virtio/dataplane/vring.h
@@ -44,7 +44,7 @@ void vring_teardown(Vring *vring, VirtIODevice *vdev, int n);
 void vring_disable_notification(VirtIODevice *vdev, Vring *vring);
 bool vring_enable_notification(VirtIODevice *vdev, Vring *vring);
 bool vring_should_notify(VirtIODevice *vdev, Vring *vring);
-int vring_pop(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem);
+void *vring_pop(VirtIODevice *vdev, Vring *vring, size_t sz);
 void vring_push(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem,
                 int len);
 

diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 09c2ce4dcd6b5b3fc54a4e1da4c4bce66b3dc0e6..35f62ac119df0fbebb28f1f75d4b7675774ae65a 100644 (file)
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -37,7 +37,7 @@ typedef struct VirtIOBalloon {
     uint32_t num_pages;
     uint32_t actual;
     uint64_t stats[VIRTIO_BALLOON_S_NR];
-    VirtQueueElement stats_vq_elem;
+    VirtQueueElement *stats_vq_elem;
     size_t stats_vq_offset;
     QEMUTimer *stats_timer;
     int64_t stats_last_update;

diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index 403ab861669d2aa33be641b80e7e9e637c4cd579..199bb0ebd5116b9078425fc7bba20ac81345a39e 100644 (file)
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -80,8 +80,7 @@ typedef struct MultiReqBuffer {
     bool is_write;
 } MultiReqBuffer;
 
-VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s);
-
+void virtio_blk_init_request(VirtIOBlock *s, VirtIOBlockReq *req);
 void virtio_blk_free_request(VirtIOBlockReq *req);
 
 void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb);

diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index f3cc25feca2bace08cb27ffbb35ec550ab37639e..2ce3b03bd4483c151120bb54bb5548f6009dd01d 100644 (file)
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -47,7 +47,7 @@ typedef struct VirtIONetQueue {
     QEMUBH *tx_bh;
     int tx_waiting;
     struct {
-        VirtQueueElement elem;
+        VirtQueueElement *elem;
     } async_tx;
     struct VirtIONet *n;
 } VirtIONetQueue;

diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index eb9d25b9fb087b9eb3e03c96c141e3588a10d6e6..a8029aa0176f326b7c7229ded869db81ebf393e9 100644 (file)
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -160,7 +160,7 @@ void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp);
 void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req);
 bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req);
 void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req);
-VirtIOSCSIReq *virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq);
+void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req);
 void virtio_scsi_free_req(VirtIOSCSIReq *req);
 void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
                             uint32_t event, uint32_t reason);

diff --git a/include/hw/virtio/virtio-serial.h b/include/hw/virtio/virtio-serial.h
index 527d0bf624f0f72d64ac42415dd5ec6e4bb5c848..12a55a19e9cde6c45de08b7ad0720860f41fec55 100644 (file)
--- a/include/hw/virtio/virtio-serial.h
+++ b/include/hw/virtio/virtio-serial.h
@@ -122,7 +122,7 @@ struct VirtIOSerialPort {
      * element popped and continue consuming it once the backend
      * becomes writable again.
      */
-    VirtQueueElement elem;
+    VirtQueueElement *elem;
 
     /*
      * The index and the offset into the iov buffer that was popped in

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 205fadf2342dca9d68d31a53ca2275fe3b6d9f9e..21fda178073841d8cea9d70b13e6d13c5ed6dc64 100644 (file)
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -152,7 +152,7 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len, unsigned int idx);
 
 void virtqueue_map(VirtQueueElement *elem);
-int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem);
+void *virtqueue_pop(VirtQueue *vq, size_t sz);
 int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,
                           unsigned int out_bytes);
 void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,