[Xen-changelog] [qemu-upstream-unstable] virtio-scsi: Fix subtle (guest) endian bug

[patchbot@xxxxxxx]

commit 863d1050c96cff91dd478767c0da9cc288575919
Author: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Date:   Mon Nov 26 12:33:52 2012 +1100

    virtio-scsi: Fix subtle (guest) endian bug
    
    The virtio-scsi config space is, by specification, in guest endian (which
    is ill-defined, but there you go).  In virtio_scsi_get_config() we set up
    all the fields in there, using stl_raw().  Which is a problem for the
    max_channel and max_target fields, which are 16-bit, not 32-bit.  For
    little-endian targets we get away with it by accident, since the first
    two bytes will still be correct, and the extra two bytes written (with
    zeroes) will be overwritten correctly by the next store.
    
    But for big-endian guests, this means the max_target field ends up as zero,
    which means the guest will only recognize a single disk on the virtio-scsi
    bus.  This patch fixes the problem.
    
    Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Cc: Paul 'Rusty' Russell <rusty@xxxxxxxxxxxxxxx>
    Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 hw/virtio-scsi.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
index 924fc69..bfe1860 100644
--- a/hw/virtio-scsi.c
+++ b/hw/virtio-scsi.c
@@ -534,8 +534,8 @@ static void virtio_scsi_get_config(VirtIODevice *vdev,
     stl_raw(&scsiconf->event_info_size, sizeof(VirtIOSCSIEvent));
     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);
+    stw_raw(&scsiconf->max_channel, VIRTIO_SCSI_MAX_CHANNEL);
+    stw_raw(&scsiconf->max_target, VIRTIO_SCSI_MAX_TARGET);
     stl_raw(&scsiconf->max_lun, VIRTIO_SCSI_MAX_LUN);
 }
 
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

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