virtio-scsi: Send "REPORTED LUNS CHANGED" sense data upon disk hotplug events

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.

When the disk inventory changes, use the bus unit attention mechanism
to return a CHECK_CONDITION status with sense data of 0x06/0x3F/0x0E
(sense code REPORTED_LUNS_CHANGED).  The first device on the bus to
execute a command successfully will report and consume the unit
attention status.

Signed-off-by: Venu Busireddy <venu.busireddy@oracle.com>
Message-Id: <20221006194946.24134-1-venu.busireddy@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 4403717..ceceafb 100644 (file)
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1616,6 +1616,24 @@ static int scsi_ua_precedence(SCSISense sense)
     return (sense.asc << 8) | sense.ascq;
 }
 
+void scsi_bus_set_ua(SCSIBus *bus, SCSISense sense)
+{
+    int prec1, prec2;
+    if (sense.key != UNIT_ATTENTION) {
+        return;
+    }
+
+    /*
+     * Override a pre-existing unit attention condition, except for a more
+     * important reset condition.
+     */
+    prec1 = scsi_ua_precedence(bus->unit_attention);
+    prec2 = scsi_ua_precedence(sense);
+    if (prec2 < prec1) {
+        bus->unit_attention = sense;
+    }
+}
+
 void scsi_device_set_ua(SCSIDevice *sdev, SCSISense sense)
 {
     int prec1, prec2;

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 41f2a56..cf2721a 100644 (file)
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -956,6 +956,7 @@ 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);
+        scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
         virtio_scsi_release(s);
     }
 }
@@ -973,6 +974,7 @@ 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);
+        scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
         virtio_scsi_release(s);
     }
 

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index 0011034..3b1b3d2 100644 (file)
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -186,6 +186,7 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
                                       BlockdevOnError rerror,
                                       BlockdevOnError werror,
                                       const char *serial, Error **errp);
+void scsi_bus_set_ua(SCSIBus *bus, SCSISense sense);
 void scsi_bus_legacy_handle_cmdline(SCSIBus *bus);
 void scsi_legacy_handle_cmdline(void);