[SCSI] virtio-scsi: SCSI driver for QEMU based virtual machines

The virtio-scsi HBA is the basis of an alternative storage stack
for QEMU-based virtual machines (including KVM).  Compared to
virtio-blk it is more scalable, because it supports many LUNs
on a single PCI slot), more powerful (it more easily supports
passthrough of host devices to the guest) and more easily
extensible (new SCSI features implemented by QEMU should not
require updating the driver in the guest).
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/Kconfig

@@ -1897,6 +1897,14 @@ config SCSI_BFA_FC
 	  To compile this driver as a module, choose M here. The module will
 	  be called bfa.
 
+config SCSI_VIRTIO
+	tristate "virtio-scsi support (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && VIRTIO
+	help
+          This is the virtual HBA driver for virtio.  If the kernel will
+          be used in a virtual machine, say Y or M.
+
+
 endif # SCSI_LOWLEVEL
 
 source "drivers/scsi/pcmcia/Kconfig"

drivers/scsi/Makefile

@@ -141,6 +141,7 @@ obj-$(CONFIG_SCSI_CXGB4_ISCSI)	+= libiscsi.o libiscsi_tcp.o cxgbi/
 obj-$(CONFIG_SCSI_BNX2_ISCSI)	+= libiscsi.o bnx2i/
 obj-$(CONFIG_BE2ISCSI)		+= libiscsi.o be2iscsi/
 obj-$(CONFIG_SCSI_PMCRAID)	+= pmcraid.o
+obj-$(CONFIG_SCSI_VIRTIO)	+= virtio_scsi.o
 obj-$(CONFIG_VMWARE_PVSCSI)	+= vmw_pvscsi.o
 
 obj-$(CONFIG_ARM)		+= arm/

include/linux/virtio_ids.h

@@ -34,6 +34,7 @@
 #define VIRTIO_ID_CONSOLE	3 /* virtio console */
 #define VIRTIO_ID_RNG		4 /* virtio ring */
 #define VIRTIO_ID_BALLOON	5 /* virtio balloon */
+#define VIRTIO_ID_SCSI		8 /* virtio scsi */
 #define VIRTIO_ID_9P		9 /* 9p virtio console */
 
 #endif /* _LINUX_VIRTIO_IDS_H */

include/linux/virtio_scsi.h

+#ifndef _LINUX_VIRTIO_SCSI_H
+#define _LINUX_VIRTIO_SCSI_H
+/* This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers. */
+
+#define VIRTIO_SCSI_CDB_SIZE   32
+#define VIRTIO_SCSI_SENSE_SIZE 96
+
+/* SCSI command request, followed by data-out */
+struct virtio_scsi_cmd_req {
+	u8 lun[8];		/* Logical Unit Number */
+	u64 tag;		/* Command identifier */
+	u8 task_attr;		/* Task attribute */
+	u8 prio;
+	u8 crn;
+	u8 cdb[VIRTIO_SCSI_CDB_SIZE];
+} __packed;
+
+/* Response, followed by sense data and data-in */
+struct virtio_scsi_cmd_resp {
+	u32 sense_len;		/* Sense data length */
+	u32 resid;		/* Residual bytes in data buffer */
+	u16 status_qualifier;	/* Status qualifier */
+	u8 status;		/* Command completion status */
+	u8 response;		/* Response values */
+	u8 sense[VIRTIO_SCSI_SENSE_SIZE];
+} __packed;
+
+/* Task Management Request */
+struct virtio_scsi_ctrl_tmf_req {
+	u32 type;
+	u32 subtype;
+	u8 lun[8];
+	u64 tag;
+} __packed;
+
+struct virtio_scsi_ctrl_tmf_resp {
+	u8 response;
+} __packed;
+
+/* Asynchronous notification query/subscription */
+struct virtio_scsi_ctrl_an_req {
+	u32 type;
+	u8 lun[8];
+	u32 event_requested;
+} __packed;
+
+struct virtio_scsi_ctrl_an_resp {
+	u32 event_actual;
+	u8 response;
+} __packed;
+
+struct virtio_scsi_event {
+	u32 event;
+	u8 lun[8];
+	u32 reason;
+} __packed;
+
+struct virtio_scsi_config {
+	u32 num_queues;
+	u32 seg_max;
+	u32 max_sectors;
+	u32 cmd_per_lun;
+	u32 event_info_size;
+	u32 sense_size;
+	u32 cdb_size;
+	u16 max_channel;
+	u16 max_target;
+	u32 max_lun;
+} __packed;
+
+/* Response codes */
+#define VIRTIO_SCSI_S_OK                       0
+#define VIRTIO_SCSI_S_OVERRUN                  1
+#define VIRTIO_SCSI_S_ABORTED                  2
+#define VIRTIO_SCSI_S_BAD_TARGET               3
+#define VIRTIO_SCSI_S_RESET                    4
+#define VIRTIO_SCSI_S_BUSY                     5
+#define VIRTIO_SCSI_S_TRANSPORT_FAILURE        6
+#define VIRTIO_SCSI_S_TARGET_FAILURE           7
+#define VIRTIO_SCSI_S_NEXUS_FAILURE            8
+#define VIRTIO_SCSI_S_FAILURE                  9
+#define VIRTIO_SCSI_S_FUNCTION_SUCCEEDED       10
+#define VIRTIO_SCSI_S_FUNCTION_REJECTED        11
+#define VIRTIO_SCSI_S_INCORRECT_LUN            12
+
+/* Controlq type codes.  */
+#define VIRTIO_SCSI_T_TMF                      0
+#define VIRTIO_SCSI_T_AN_QUERY                 1
+#define VIRTIO_SCSI_T_AN_SUBSCRIBE             2
+
+/* Valid TMF subtypes.  */
+#define VIRTIO_SCSI_T_TMF_ABORT_TASK           0
+#define VIRTIO_SCSI_T_TMF_ABORT_TASK_SET       1
+#define VIRTIO_SCSI_T_TMF_CLEAR_ACA            2
+#define VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET       3
+#define VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET      4
+#define VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET   5
+#define VIRTIO_SCSI_T_TMF_QUERY_TASK           6
+#define VIRTIO_SCSI_T_TMF_QUERY_TASK_SET       7
+
+/* Events.  */
+#define VIRTIO_SCSI_T_EVENTS_MISSED            0x80000000
+#define VIRTIO_SCSI_T_NO_EVENT                 0
+#define VIRTIO_SCSI_T_TRANSPORT_RESET          1
+#define VIRTIO_SCSI_T_ASYNC_NOTIFY             2
+
+#define VIRTIO_SCSI_S_SIMPLE                   0
+#define VIRTIO_SCSI_S_ORDERED                  1
+#define VIRTIO_SCSI_S_HEAD                     2
+#define VIRTIO_SCSI_S_ACA                      3
+
+
+#endif /* _LINUX_VIRTIO_SCSI_H */