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[Qemu-devel] [RFC PATCH v2 10/10] virtio-scsi: Hook up with dataplane


From: Fam Zheng
Subject: [Qemu-devel] [RFC PATCH v2 10/10] virtio-scsi: Hook up with dataplane
Date: Wed, 6 Aug 2014 13:35:08 +0800

This enables the virtio-scsi-dataplane code by setting the iothread
in virtio-scsi device, and makes any function that is called by
back from dataplane to cooperate with the caller: they need to be
vring/iothread aware when handling the requests and using scsi devices
on the bus.

Signed-off-by: Fam Zheng <address@hidden>
---
 hw/scsi/virtio-scsi.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 71 insertions(+), 3 deletions(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 9e78e21..1f2a9b6 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -62,6 +62,22 @@ void virtio_scsi_free_req(VirtIOSCSIReq *req)
     g_free(req);
 }
 
+static void virtio_scsi_aio_acquire(VirtIOSCSICommon *vs)
+{
+    if (vs->dataplane_started) {
+        assert(vs->ctx);
+        aio_context_acquire(vs->ctx);
+    }
+}
+
+static void virtio_scsi_aio_release(VirtIOSCSICommon *vs)
+{
+    if (vs->dataplane_started) {
+        assert(vs->ctx);
+        aio_context_release(vs->ctx);
+    }
+}
+
 static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
 {
     VirtIOSCSI *s = req->dev;
@@ -69,13 +85,19 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 
     qemu_iovec_from_buf(&req->resp_iov, 0, &req->resp, req->resp_size);
-    virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
+    if (req->vring) {
+        assert(req->vq == NULL);
+        virtio_scsi_vring_push_notify(req);
+    } else {
+        virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
+        virtio_notify(vdev, vq);
+    }
+
     if (req->sreq) {
         req->sreq->hba_private = NULL;
         scsi_req_unref(req->sreq);
     }
     virtio_scsi_free_req(req);
-    virtio_notify(vdev, vq);
 }
 
 static void virtio_scsi_bad_req(void)
@@ -204,10 +226,16 @@ static void *virtio_scsi_load_request(QEMUFile *f, 
SCSIRequest *sreq)
 static void virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 {
     SCSIDevice *d = virtio_scsi_device_find(s, req->req.tmf.lun);
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
     SCSIRequest *r, *next;
     BusChild *kid;
     int target;
 
+    if (vs->dataplane_started && bdrv_get_aio_context(d->conf.bs) != vs->ctx) {
+        aio_context_acquire(vs->ctx);
+        bdrv_set_aio_context(d->conf.bs, vs->ctx);
+        aio_context_release(vs->ctx);
+    }
     /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
     req->resp.tmf.response = VIRTIO_SCSI_S_OK;
 
@@ -344,8 +372,13 @@ void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, 
VirtIOSCSIReq *req)
 static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOSCSI *s = (VirtIOSCSI *)vdev;
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vdev;
     VirtIOSCSIReq *req;
 
+    if (vs->ctx) {
+        virtio_scsi_dataplane_start(vs);
+        return;
+    }
     while ((req = virtio_scsi_pop_req(s, vq))) {
         virtio_scsi_handle_ctrl_req(s, req);
     }
@@ -439,6 +472,11 @@ void virtio_scsi_handle_cmd_req(VirtIOSCSI *s, 
VirtIOSCSIReq *req)
         virtio_scsi_complete_cmd_req(req);
         return;
     }
+    if (vs->dataplane_started && bdrv_get_aio_context(d->conf.bs) != vs->ctx) {
+        aio_context_acquire(vs->ctx);
+        bdrv_set_aio_context(d->conf.bs, vs->ctx);
+        aio_context_release(vs->ctx);
+    }
     req->sreq = scsi_req_new(d, req->req.cmd.tag,
                              virtio_scsi_get_lun(req->req.cmd.lun),
                              req->req.cdb, req);
@@ -461,8 +499,13 @@ static void virtio_scsi_handle_cmd(VirtIODevice *vdev, 
VirtQueue *vq)
 {
     /* use non-QOM casts in the data path */
     VirtIOSCSI *s = (VirtIOSCSI *)vdev;
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vdev;
     VirtIOSCSIReq *req;
 
+    if (vs->ctx) {
+        virtio_scsi_dataplane_start(vs);
+        return;
+    }
     while ((req = virtio_scsi_pop_req(s, vq))) {
         virtio_scsi_handle_cmd_req(s, req);
     }
@@ -513,6 +556,9 @@ static void virtio_scsi_reset(VirtIODevice *vdev)
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
 
+    if (vs->ctx) {
+        virtio_scsi_dataplane_stop(vs);
+    }
     s->resetting++;
     qbus_reset_all(&s->bus.qbus);
     s->resetting--;
@@ -555,7 +601,11 @@ void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
         return;
     }
 
-    req = virtio_scsi_pop_req(s, vs->event_vq);
+    if (vs->dataplane_started) {
+        req = virtio_scsi_pop_req_vring(s, vs->event_vring);
+    } else {
+        req = virtio_scsi_pop_req(s, vs->event_vq);
+    }
     if (!req) {
         s->events_dropped = true;
         return;
@@ -592,7 +642,12 @@ void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
 static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vdev;
 
+    if (vs->ctx) {
+        virtio_scsi_dataplane_start(vs);
+        return;
+    }
     if (s->events_dropped) {
         virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
     }
@@ -602,11 +657,14 @@ static void virtio_scsi_change(SCSIBus *bus, SCSIDevice 
*dev, SCSISense sense)
 {
     VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vdev;
 
     if (((vdev->guest_features >> VIRTIO_SCSI_F_CHANGE) & 1) &&
         dev->type != TYPE_ROM) {
+        virtio_scsi_aio_acquire(vs);
         virtio_scsi_push_event(s, dev, VIRTIO_SCSI_T_PARAM_CHANGE,
                                sense.asc | (sense.ascq << 8));
+        virtio_scsi_aio_release(vs);
     }
 }
 
@@ -614,10 +672,13 @@ static void virtio_scsi_hotplug(SCSIBus *bus, SCSIDevice 
*dev)
 {
     VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vdev;
 
     if ((vdev->guest_features >> VIRTIO_SCSI_F_HOTPLUG) & 1) {
+        virtio_scsi_aio_acquire(vs);
         virtio_scsi_push_event(s, dev, VIRTIO_SCSI_T_TRANSPORT_RESET,
                                VIRTIO_SCSI_EVT_RESET_RESCAN);
+        virtio_scsi_aio_release(vs);
     }
 }
 
@@ -625,10 +686,13 @@ static void virtio_scsi_hot_unplug(SCSIBus *bus, 
SCSIDevice *dev)
 {
     VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vdev;
 
     if ((vdev->guest_features >> VIRTIO_SCSI_F_HOTPLUG) & 1) {
+        virtio_scsi_aio_acquire(vs);
         virtio_scsi_push_event(s, dev, VIRTIO_SCSI_T_TRANSPORT_RESET,
                                VIRTIO_SCSI_EVT_RESET_REMOVED);
+        virtio_scsi_aio_release(vs);
     }
 }
 
@@ -671,6 +735,10 @@ void virtio_scsi_common_realize(DeviceState *dev, Error 
**errp,
         s->cmd_vqs[i] = virtio_add_queue(vdev, VIRTIO_SCSI_VQ_SIZE,
                                          cmd);
     }
+
+    if (s->conf.iothread) {
+        virtio_scsi_set_iothread(s, s->conf.iothread);
+    }
 }
 
 static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
-- 
2.0.3




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