On Wed, Nov 02, 2011 at 01:19:40PM +0100, 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.
Do the bit offsets happen to be defined in some header?
Also, Signed-off-by is missing?
> ---
> 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);
> --
> 1.7.6.4
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