Re: [Qemu-devel] [PATCH 1.0] virtio-blk: pass full status to the guest

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On 11/02/2011 07:19 AM, Paolo Bonzini wrote:
When SCSI passthrough is being used by the guest with virtio-blk, the
guest is not able to detect disk failures.  This is because the status
field is expected by the guest driver to include also the msg_status,
host_status and driver_status fields, but the device is only passing
down the SCSI status.

The patch fixes this, and also makes sure that the guest always sees a
CHECK_CONDITION status when there is valid sense data.
---

Applied.  Thanks.

Regards,

Anthony Liguori

	Sorry for missing the -rc deadline, testing this requires
	Fibre Channel stuff so I needed someone to do it for me. :)

  hw/virtio-blk.c |   16 +++++++++++++++-
  1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 179747a..8beaa20 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -16,6 +16,7 @@
  #include "trace.h"
  #include "blockdev.h"
  #include "virtio-blk.h"
+#include "scsi-defs.h"
  #ifdef __linux__
  # include<scsi/sg.h>
  #endif
@@ -231,7 +232,20 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
          status = VIRTIO_BLK_S_OK;
      }

-    stl_p(&req->scsi->errors, hdr.status);
+    /*
+     * From SCSI-Generic-HOWTO: "Some lower level drivers (e.g. ide-scsi)
+     * clear the masked_status field [hence status gets cleared too, see
+     * block/scsi_ioctl.c] even when a CHECK_CONDITION or COMMAND_TERMINATED
+     * status has occurred.  However they do set DRIVER_SENSE in driver_status
+     * field. Also a (sb_len_wr>  0) indicates there is a sense buffer.
+     */
+    if (hdr.status == 0&&  hdr.sb_len_wr>  0) {
+        hdr.status = CHECK_CONDITION;
+    }
+
+    stl_p(&req->scsi->errors,
+          hdr.status | (hdr.msg_status<<  8) |
+          (hdr.host_status<<  16) | (hdr.driver_status<<  24));
      stl_p(&req->scsi->residual, hdr.resid);
      stl_p(&req->scsi->sense_len, hdr.sb_len_wr);
      stl_p(&req->scsi->data_len, hdr.dxfer_len);

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