[PATCH] hw/virtio-scsi: Set max_target=0 during vhost-scsi operation

["Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx>]

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

This QEMU patch sets VirtIOSCSIConfig->max_target=0 for vhost-scsi operation
to restrict virtio-scsi LLD guest scanning to max_id=0 (a single target ID
instance) when connected to individual tcm_vhost endpoints as requested by
Paolo.

This ensures that virtio-scsi LLD only attempts to scan target IDs up to
VIRTIO_SCSI_MAX_TARGET when connected via virtio-scsi-raw.

It's currently cut against Zhi's qemu vhost-scsi tree here:

   https://github.com/wuzhy/qemu/tree/vhost-scsi

Cc: Stefan Hajnoczi <stefanha@xxxxxxxxxxxxxxxxxx>
Cc: Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
 hw/virtio-scsi.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
index e38cdd0..71276b6 100644
--- a/hw/virtio-scsi.c
+++ b/hw/virtio-scsi.c
@@ -523,7 +523,11 @@ static void virtio_scsi_get_config(VirtIODevice *vdev,
     stl_raw(&scsiconf->sense_size, s->sense_size);
     stl_raw(&scsiconf->cdb_size, s->cdb_size);
     stl_raw(&scsiconf->max_channel, VIRTIO_SCSI_MAX_CHANNEL);
-    stl_raw(&scsiconf->max_target, VIRTIO_SCSI_MAX_TARGET);
+    if (s->vhost_scsi) {
+        stl_raw(&scsiconf->max_target, 0);
+    } else {
+        stl_raw(&scsiconf->max_target, VIRTIO_SCSI_MAX_TARGET);
+    }
     stl_raw(&scsiconf->max_lun, VIRTIO_SCSI_MAX_LUN);
 }
 
-- 
1.7.2.5

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