[Qemu-devel] [PATCH 3/3] virtio-scsi: add multiqueue capability

[Paolo Bonzini]

Adding multiqueue is as simple as creating more than one virtqueues,
and saving the queue number for each request.

Signed-off-by: Paolo Bonzini <address@hidden>
---
 hw/virtio-scsi.c |   25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
index 0d90d9c..e8328f4 100644
--- a/hw/virtio-scsi.c
+++ b/hw/virtio-scsi.c
@@ -129,12 +129,12 @@ typedef struct {
     VirtIOSCSIConf *conf;
 
     SCSIBus bus;
-    VirtQueue *ctrl_vq;
-    VirtQueue *event_vq;
-    VirtQueue *cmd_vq;
     uint32_t sense_size;
     uint32_t cdb_size;
     int resetting;
+    VirtQueue *ctrl_vq;
+    VirtQueue *event_vq;
+    VirtQueue *cmd_vqs[0];
 } VirtIOSCSI;
 
 typedef struct VirtIOSCSIReq {
@@ -240,8 +240,9 @@ static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, 
VirtQueue *vq)
 static void virtio_scsi_save_request(QEMUFile *f, SCSIRequest *sreq)
 {
     VirtIOSCSIReq *req = sreq->hba_private;
-    uint32_t n = 0;
+    uint32_t n = virtio_queue_get_id(req->vq) - 2;
 
+    assert(n < req->dev->conf->num_queues);
     qemu_put_be32s(f, &n);
     qemu_put_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));
 }
@@ -255,9 +256,9 @@ static void *virtio_scsi_load_request(QEMUFile *f, 
SCSIRequest *sreq)
 
     req = g_malloc(sizeof(*req));
     qemu_get_be32s(f, &n);
-    assert(n == 0);
+    assert(n < s->conf->num_queues);
     qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));
-    virtio_scsi_parse_req(s, s->cmd_vq, req);
+    virtio_scsi_parse_req(s, s->cmd_vqs[n], req);
 
     scsi_req_ref(sreq);
     req->sreq = sreq;
@@ -584,10 +585,12 @@ VirtIODevice *virtio_scsi_init(DeviceState *dev, 
VirtIOSCSIConf *proxyconf)
 {
     VirtIOSCSI *s;
     static int virtio_scsi_id;
+    size_t sz;
+    int i;
 
+    sz = sizeof(VirtIOSCSI) + proxyconf->num_queues * sizeof(VirtQueue *);
     s = (VirtIOSCSI *)virtio_common_init("virtio-scsi", VIRTIO_ID_SCSI,
-                                         sizeof(VirtIOSCSIConfig),
-                                         sizeof(VirtIOSCSI));
+                                         sizeof(VirtIOSCSIConfig), sz);
 
     s->qdev = dev;
     s->conf = proxyconf;
@@ -602,8 +605,10 @@ VirtIODevice *virtio_scsi_init(DeviceState *dev, 
VirtIOSCSIConf *proxyconf)
                                    virtio_scsi_handle_ctrl);
     s->event_vq = virtio_add_queue(&s->vdev, VIRTIO_SCSI_VQ_SIZE,
                                    NULL);
-    s->cmd_vq = virtio_add_queue(&s->vdev, VIRTIO_SCSI_VQ_SIZE,
-                                   virtio_scsi_handle_cmd);
+    for (i = 0; i < s->conf->num_queues; i++) {
+        s->cmd_vqs[i] = virtio_add_queue(&s->vdev, VIRTIO_SCSI_VQ_SIZE,
+                                         virtio_scsi_handle_cmd);
+    }
 
     scsi_bus_new(&s->bus, dev, &virtio_scsi_scsi_info);
     if (!dev->hotplugged) {
-- 
1.7.9.3