tcm_vhost: Initial merge for vhost level target fabric driver

This patch adds the initial code for tcm_vhost, a Vhost level TCM
fabric driver for virtio SCSI initiators into KVM guest.

This code is currently up and running on v3.5-rc2 host+guest
from target-pending/for-next-merge.

Using tcm_vhost requires Zhi's -> Stefan -> nab's qemu vhost-scsi tree here:

  http://git.kernel.org/?p=virt/kvm/nab/qemu-kvm.git;a=shortlog;h=refs/heads/vhost-scsi

--

Changelog v4 -> v5:

  Expose ABI version via VHOST_SCSI_GET_ABI_VERSION + use Rev 0 as
  starting point for v3.6-rc code (Stefan + ALiguori + nab)
  Convert vhost_scsi_handle_vq() to vq_err() (nab + MST)
  Minor style fixes from checkpatch (nab)

Changelog v3 -> v4:

  Rename vhost_vring_target -> vhost_scsi_target (mst + nab)
  Use TRANSPORT_IQN_LEN in vhost_scsi_target->vhost_wwpn[] def (nab)
  Move back to drivers/vhost/, and just use drivers/vhost/Kconfig.tcm (mst)
  Move TCM_VHOST related ioctl defines from include/linux/vhost.h ->
  drivers/vhost/tcm_vhost.h as requested by MST (nab)
  Move Kbuild.tcm include from drivers/staging -> drivers/vhost/, and
  just use 'if STAGING' around 'source drivers/vhost/Kbuild.tcm'

Changelog v2 -> v3:

  Unlock on error in tcm_vhost_drop_nexus() (DanC)
  Fix strlen() doesn't count the terminator (DanC)
  Call kfree() on an error path (DanC)
  Convert tcm_vhost_write_pending to use target_execute_cmd (hch + nab)
  Fix another strlen() off by one in tcm_vhost_make_tport (DanC)
  Add option under drivers/staging/Kconfig, and move to drivers/vhost/tcm/
  as requested by MST (nab)

Changelog v1 -> v2:

  Fix tv_cmd completion -> release SGL memory leak (nab)
  Fix sparse warnings for static variable usage ((Fengguang Wu)
  Fix sparse warnings for min() typing + printk format specs (Fengguang Wu)
  Convert to cmwq submission for I/O dispatch (nab + hch)

Changelog v0 -> v1:

  Merge into single source + header file, and move to drivers/vhost/

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Cc: Zhi Yong Wu <wuzhy@cn.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 101 insertions, 0 deletions

diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
new file mode 100644
index 000000000000..c983ed21e413
--- /dev/null
+++ b/drivers/vhost/tcm_vhost.h
@@ -0,0 +1,101 @@
+#define TCM_VHOST_VERSION  "v0.1"
+#define TCM_VHOST_NAMELEN 256
+#define TCM_VHOST_MAX_CDB_SIZE 32
+
+struct tcm_vhost_cmd {
+        /* Descriptor from vhost_get_vq_desc() for virt_queue segment */
+        int tvc_vq_desc;
+        /* The Tag from include/linux/virtio_scsi.h:struct virtio_scsi_cmd_req */
+        u64 tvc_tag;
+        /* The number of scatterlists associated with this cmd */
+        u32 tvc_sgl_count;
+        /* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
+        u32 tvc_lun;
+        /* Pointer to the SGL formatted memory from virtio-scsi */
+        struct scatterlist *tvc_sgl;
+        /* Pointer to response */
+        struct virtio_scsi_cmd_resp __user *tvc_resp;
+        /* Pointer to vhost_scsi for our device */
+        struct vhost_scsi *tvc_vhost;
+        /* The TCM I/O descriptor that is accessed via container_of() */
+        struct se_cmd tvc_se_cmd;
+        /* work item used for cmwq dispatch to tcm_vhost_submission_work() */
+        struct work_struct work;
+        /* Copy of the incoming SCSI command descriptor block (CDB) */
+        unsigned char tvc_cdb[TCM_VHOST_MAX_CDB_SIZE];
+        /* Sense buffer that will be mapped into outgoing status */
+        unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER];
+        /* Completed commands list, serviced from vhost worker thread */
+        struct list_head tvc_completion_list;
+};
+
+struct tcm_vhost_nexus {
+        /* Pointer to TCM session for I_T Nexus */
+        struct se_session *tvn_se_sess;
+};
+
+struct tcm_vhost_nacl {
+        /* Binary World Wide unique Port Name for Vhost Initiator port */
+        u64 iport_wwpn;
+        /* ASCII formatted WWPN for Sas Initiator port */
+        char iport_name[TCM_VHOST_NAMELEN];
+        /* Returned by tcm_vhost_make_nodeacl() */
+        struct se_node_acl se_node_acl;
+};
+
+struct tcm_vhost_tpg {
+        /* Vhost port target portal group tag for TCM */
+        u16 tport_tpgt;
+        /* Used to track number of TPG Port/Lun Links wrt to explict I_T Nexus shutdown */
+        atomic_t tv_tpg_port_count;
+        /* Used for vhost_scsi device reference to tpg_nexus */
+        atomic_t tv_tpg_vhost_count;
+        /* list for tcm_vhost_list */
+        struct list_head tv_tpg_list;
+        /* Used to protect access for tpg_nexus */
+        struct mutex tv_tpg_mutex;
+        /* Pointer to the TCM VHost I_T Nexus for this TPG endpoint */
+        struct tcm_vhost_nexus *tpg_nexus;
+        /* Pointer back to tcm_vhost_tport */
+        struct tcm_vhost_tport *tport;
+        /* Returned by tcm_vhost_make_tpg() */
+        struct se_portal_group se_tpg;
+};
+
+struct tcm_vhost_tport {
+        /* SCSI protocol the tport is providing */
+        u8 tport_proto_id;
+        /* Binary World Wide unique Port Name for Vhost Target port */
+        u64 tport_wwpn;
+        /* ASCII formatted WWPN for Vhost Target port */
+        char tport_name[TCM_VHOST_NAMELEN];
+        /* Returned by tcm_vhost_make_tport() */
+        struct se_wwn tport_wwn;
+};
+
+/*
+ * As per request from MST, keep TCM_VHOST related ioctl defines out of
+ * linux/vhost.h (user-space) for now..
+ */
+
+#include <linux/vhost.h>
+
+/*
+ * Used by QEMU userspace to ensure a consistent vhost-scsi ABI.
+ *
+ * ABI Rev 0: July 2012 version starting point for v3.6-rc merge candidate +
+ *            RFC-v2 vhost-scsi userspace.  Add GET_ABI_VERSION ioctl usage
+ */
+
+#define VHOST_SCSI_ABI_VERSION  0
+
+struct vhost_scsi_target {
+        int abi_version;
+        unsigned char vhost_wwpn[TRANSPORT_IQN_LEN];
+        unsigned short vhost_tpgt;
+};
+
+/* VHOST_SCSI specific defines */
+#define VHOST_SCSI_SET_ENDPOINT _IOW(VHOST_VIRTIO, 0x40, struct vhost_scsi_target)
+#define VHOST_SCSI_CLEAR_ENDPOINT _IOW(VHOST_VIRTIO, 0x41, struct vhost_scsi_target)
+#define VHOST_SCSI_GET_ABI_VERSION _IOW(VHOST_VIRTIO, 0x42, struct vhost_scsi_target)