virtio-blk: add SGI_IO passthru support

[had the qemu list address wrong the first time, reply to this message,
 not the previous if you were on Cc]

Add support for SG_IO passthru (packet commands) to the virtio-blk
backend.  Conceptually based on an older patch from Hannes Reinecke
but largely rewritten to match the code structure and layering in
virtio-blk.

Note that currently we issue the hose SG_IO synchronously.  We could
easily switch to async I/O, but that would required either bloating
the VirtIOBlockReq by the size of struct sg_io_hdr or an additional
memory allocation for each SG_IO request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h
index 8c91e1ece6..d11f484945 100644
--- a/hw/virtio-blk.h
+++ b/hw/virtio-blk.h
@@ -28,6 +28,9 @@
 #define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
 #define VIRTIO_BLK_F_SEG_MAX    2       /* Indicates maximum # of segments */
 #define VIRTIO_BLK_F_GEOMETRY   4       /* Indicates support of legacy geometry */
+#define VIRTIO_BLK_F_RO         5       /* Disk is read-only */
+#define VIRTIO_BLK_F_BLK_SIZE   6       /* Block size of disk is available*/
+#define VIRTIO_BLK_F_SCSI       7       /* Supports scsi command passthru */
 
 struct virtio_blk_config
 {
@@ -70,6 +73,15 @@ struct virtio_blk_inhdr
     unsigned char status;
 };
 
+/* SCSI pass-through header */
+struct virtio_scsi_inhdr
+{
+    uint32_t errors;
+    uint32_t data_len;
+    uint32_t sense_len;
+    uint32_t residual;
+};
+
 void *virtio_blk_init(PCIBus *bus, BlockDriverState *bs);
 
 #endif