[PATCH v2] virtio-scsi: Send "REPORTED LUNS CHANGED" sense data upon disk hotplug events.

[Venu Busireddy <venu.busireddy@oracle.com>]

Section 5.6.6.3 of VirtIO specification states, "Events will also
be reported via sense codes..." However, no sense data is sent when
VIRTIO_SCSI_EVT_RESET_RESCAN or VIRTIO_SCSI_EVT_RESET_REMOVED events
are reported (when disk hotplug/hotunplug events occur). SCSI layer
on Solaris depends on this sense data, and hence does not handle disk
hotplug/hotunplug events.

As specified in SAM-4, Section 5.14 (h), return a CHECK_CONDITION status
with sense data of 0x06/0x3F/0x0E (sense code REPORTED_LUNS_CHANGED) when
the disk inventory changes and a command other than INQUIRY, REPORT_LUNS,
or REQUEST_SENSE is received.

Signed-off-by: Venu Busireddy <venu.busireddy@oracle.com>

v1 -> v2:
    - Send the sense data for VIRTIO_SCSI_EVT_RESET_REMOVED event too.
---
 hw/scsi/virtio-scsi.c           | 16 +++++++++++++++-
 include/hw/virtio/virtio-scsi.h |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 41f2a5630173..69194c7ae23c 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -608,7 +608,19 @@ static void virtio_scsi_command_complete(SCSIRequest *r, size_t resid)
 
     req->resp.cmd.response = VIRTIO_SCSI_S_OK;
     req->resp.cmd.status = r->status;
-    if (req->resp.cmd.status == GOOD) {
+    if (req->dev->reported_luns_changed &&
+            (req->req.cmd.cdb[0] != INQUIRY) &&
+            (req->req.cmd.cdb[0] != REPORT_LUNS) &&
+            (req->req.cmd.cdb[0] != REQUEST_SENSE)) {
+        req->dev->reported_luns_changed = false;
+        req->resp.cmd.resid = 0;
+        req->resp.cmd.status_qualifier = 0;
+        req->resp.cmd.status = CHECK_CONDITION;
+        sense_len = scsi_build_sense(sense, SENSE_CODE(REPORTED_LUNS_CHANGED));
+        qemu_iovec_from_buf(&req->resp_iov, sizeof(req->resp.cmd),
+                            sense, sense_len);
+        req->resp.cmd.sense_len = virtio_tswap32(vdev, sense_len);
+    } else if (req->resp.cmd.status == GOOD) {
         req->resp.cmd.resid = virtio_tswap32(vdev, resid);
     } else {
         req->resp.cmd.resid = 0;
@@ -956,6 +968,7 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
         virtio_scsi_push_event(s, sd,
                                VIRTIO_SCSI_T_TRANSPORT_RESET,
                                VIRTIO_SCSI_EVT_RESET_RESCAN);
+        s->reported_luns_changed = true;
         virtio_scsi_release(s);
     }
 }
@@ -973,6 +986,7 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
         virtio_scsi_push_event(s, sd,
                                VIRTIO_SCSI_T_TRANSPORT_RESET,
                                VIRTIO_SCSI_EVT_RESET_REMOVED);
+        s->reported_luns_changed = true;
         virtio_scsi_release(s);
     }
 
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index a36aad9c8695..efbcf9ba069a 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -81,6 +81,7 @@ struct VirtIOSCSI {
     SCSIBus bus;
     int resetting;
     bool events_dropped;
+    bool reported_luns_changed;
 
     /* Fields for dataplane below */
     AioContext *ctx; /* one iothread per virtio-scsi-pci for now */