Based on kernel version 2.6.26. Page generated on 2008-07-16 21:13 EST.
1 SCSI FC Tansport 2 ============================================= 3 4 Date: 4/12/2007 5 Kernel Revisions for features: 6 rports : <<TBS>> 7 vports : 2.6.22 (? TBD) 8 9 10 Introduction 11 ============ 12 This file documents the features and components of the SCSI FC Transport. 13 It also provides documents the API between the transport and FC LLDDs. 14 The FC transport can be found at: 15 drivers/scsi/scsi_transport_fc.c 16 include/scsi/scsi_transport_fc.h 17 include/scsi/scsi_netlink_fc.h 18 19 This file is found at Documentation/scsi/scsi_fc_transport.txt 20 21 22 FC Remote Ports (rports) 23 ======================================================================== 24 << To Be Supplied >> 25 26 27 FC Virtual Ports (vports) 28 ======================================================================== 29 30 Overview: 31 ------------------------------- 32 33 New FC standards have defined mechanisms which allows for a single physical 34 port to appear on as multiple communication ports. Using the N_Port Id 35 Virtualization (NPIV) mechanism, a point-to-point connection to a Fabric 36 can be assigned more than 1 N_Port_ID. Each N_Port_ID appears as a 37 separate port to other endpoints on the fabric, even though it shares one 38 physical link to the switch for communication. Each N_Port_ID can have a 39 unique view of the fabric based on fabric zoning and array lun-masking 40 (just like a normal non-NPIV adapter). Using the Virtual Fabric (VF) 41 mechanism, adding a fabric header to each frame allows the port to 42 interact with the Fabric Port to join multiple fabrics. The port will 43 obtain an N_Port_ID on each fabric it joins. Each fabric will have its 44 own unique view of endpoints and configuration parameters. NPIV may be 45 used together with VF so that the port can obtain multiple N_Port_IDs 46 on each virtual fabric. 47 48 The FC transport is now recognizing a new object - a vport. A vport is 49 an entity that has a world-wide unique World Wide Port Name (wwpn) and 50 World Wide Node Name (wwnn). The transport also allows for the FC4's to 51 be specified for the vport, with FCP_Initiator being the primary role 52 expected. Once instantiated by one of the above methods, it will have a 53 distinct N_Port_ID and view of fabric endpoints and storage entities. 54 The fc_host associated with the physical adapter will export the ability 55 to create vports. The transport will create the vport object within the 56 Linux device tree, and instruct the fc_host's driver to instantiate the 57 virtual port. Typically, the driver will create a new scsi_host instance 58 on the vport, resulting in a unique <H,C,T,L> namespace for the vport. 59 Thus, whether a FC port is based on a physical port or on a virtual port, 60 each will appear as a unique scsi_host with its own target and lun space. 61 62 Note: At this time, the transport is written to create only NPIV-based 63 vports. However, consideration was given to VF-based vports and it 64 should be a minor change to add support if needed. The remaining 65 discussion will concentrate on NPIV. 66 67 Note: World Wide Name assignment (and uniqueness guarantees) are left 68 up to an administrative entity controling the vport. For example, 69 if vports are to be associated with virtual machines, a XEN mgmt 70 utility would be responsible for creating wwpn/wwnn's for the vport, 71 using it's own naming authority and OUI. (Note: it already does this 72 for virtual MAC addresses). 73 74 75 Device Trees and Vport Objects: 76 ------------------------------- 77 78 Today, the device tree typically contains the scsi_host object, 79 with rports and scsi target objects underneath it. Currently the FC 80 transport creates the vport object and places it under the scsi_host 81 object corresponding to the physical adapter. The LLDD will allocate 82 a new scsi_host for the vport and link it's object under the vport. 83 The remainder of the tree under the vports scsi_host is the same 84 as the non-NPIV case. The transport is written currently to easily 85 allow the parent of the vport to be something other than the scsi_host. 86 This could be used in the future to link the object onto a vm-specific 87 device tree. If the vport's parent is not the physical port's scsi_host, 88 a symbolic link to the vport object will be placed in the physical 89 port's scsi_host. 90 91 Here's what to expect in the device tree : 92 The typical Physical Port's Scsi_Host: 93 /sys/devices/.../host17/ 94 and it has the typical decendent tree: 95 /sys/devices/.../host17/rport-17:0-0/target17:0:0/17:0:0:0: 96 and then the vport is created on the Physical Port: 97 /sys/devices/.../host17/vport-17:0-0 98 and the vport's Scsi_Host is then created: 99 /sys/devices/.../host17/vport-17:0-0/host18 100 and then the rest of the tree progresses, such as: 101 /sys/devices/.../host17/vport-17:0-0/host18/rport-18:0-0/target18:0:0/18:0:0:0: 102 103 Here's what to expect in the sysfs tree : 104 scsi_hosts: 105 /sys/class/scsi_host/host17 physical port's scsi_host 106 /sys/class/scsi_host/host18 vport's scsi_host 107 fc_hosts: 108 /sys/class/fc_host/host17 physical port's fc_host 109 /sys/class/fc_host/host18 vport's fc_host 110 fc_vports: 111 /sys/class/fc_vports/vport-17:0-0 the vport's fc_vport 112 fc_rports: 113 /sys/class/fc_remote_ports/rport-17:0-0 rport on the physical port 114 /sys/class/fc_remote_ports/rport-18:0-0 rport on the vport 115 116 117 Vport Attributes: 118 ------------------------------- 119 120 The new fc_vport class object has the following attributes 121 122 node_name: Read_Only 123 The WWNN of the vport 124 125 port_name: Read_Only 126 The WWPN of the vport 127 128 roles: Read_Only 129 Indicates the FC4 roles enabled on the vport. 130 131 symbolic_name: Read_Write 132 A string, appended to the driver's symbolic port name string, which 133 is registered with the switch to identify the vport. For example, 134 a hypervisor could set this string to "Xen Domain 2 VM 5 Vport 2", 135 and this set of identifiers can be seen on switch management screens 136 to identify the port. 137 138 vport_delete: Write_Only 139 When written with a "1", will tear down the vport. 140 141 vport_disable: Write_Only 142 When written with a "1", will transition the vport to a disabled. 143 state. The vport will still be instantiated with the Linux kernel, 144 but it will not be active on the FC link. 145 When written with a "0", will enable the vport. 146 147 vport_last_state: Read_Only 148 Indicates the previous state of the vport. See the section below on 149 "Vport States". 150 151 vport_state: Read_Only 152 Indicates the state of the vport. See the section below on 153 "Vport States". 154 155 vport_type: Read_Only 156 Reflects the FC mechanism used to create the virtual port. 157 Only NPIV is supported currently. 158 159 160 For the fc_host class object, the following attributes are added for vports: 161 162 max_npiv_vports: Read_Only 163 Indicates the maximum number of NPIV-based vports that the 164 driver/adapter can support on the fc_host. 165 166 npiv_vports_inuse: Read_Only 167 Indicates how many NPIV-based vports have been instantiated on the 168 fc_host. 169 170 vport_create: Write_Only 171 A "simple" create interface to instantiate a vport on an fc_host. 172 A "<WWPN>:<WWNN>" string is written to the attribute. The transport 173 then instantiates the vport object and calls the LLDD to create the 174 vport with the role of FCP_Initiator. Each WWN is specified as 16 175 hex characters and may *not* contain any prefixes (e.g. 0x, x, etc). 176 177 vport_delete: Write_Only 178 A "simple" delete interface to teardown a vport. A "<WWPN>:<WWNN>" 179 string is written to the attribute. The transport will locate the 180 vport on the fc_host with the same WWNs and tear it down. Each WWN 181 is specified as 16 hex characters and may *not* contain any prefixes 182 (e.g. 0x, x, etc). 183 184 185 Vport States: 186 ------------------------------- 187 188 Vport instantiation consists of two parts: 189 - Creation with the kernel and LLDD. This means all transport and 190 driver data structures are built up, and device objects created. 191 This is equivalent to a driver "attach" on an adapter, which is 192 independent of the adapter's link state. 193 - Instantiation of the vport on the FC link via ELS traffic, etc. 194 This is equivalent to a "link up" and successfull link initialization. 195 Futher information can be found in the interfaces section below for 196 Vport Creation. 197 198 Once a vport has been instantiated with the kernel/LLDD, a vport state 199 can be reported via the sysfs attribute. The following states exist: 200 201 FC_VPORT_UNKNOWN - Unknown 202 An temporary state, typically set only while the vport is being 203 instantiated with the kernel and LLDD. 204 205 FC_VPORT_ACTIVE - Active 206 The vport has been successfully been created on the FC link. 207 It is fully functional. 208 209 FC_VPORT_DISABLED - Disabled 210 The vport instantiated, but "disabled". The vport is not instantiated 211 on the FC link. This is equivalent to a physical port with the 212 link "down". 213 214 FC_VPORT_LINKDOWN - Linkdown 215 The vport is not operational as the physical link is not operational. 216 217 FC_VPORT_INITIALIZING - Initializing 218 The vport is in the process of instantiating on the FC link. 219 The LLDD will set this state just prior to starting the ELS traffic 220 to create the vport. This state will persist until the vport is 221 successfully created (state becomes FC_VPORT_ACTIVE) or it fails 222 (state is one of the values below). As this state is transitory, 223 it will not be preserved in the "vport_last_state". 224 225 FC_VPORT_NO_FABRIC_SUPP - No Fabric Support 226 The vport is not operational. One of the following conditions were 227 encountered: 228 - The FC topology is not Point-to-Point 229 - The FC port is not connected to an F_Port 230 - The F_Port has indicated that NPIV is not supported. 231 232 FC_VPORT_NO_FABRIC_RSCS - No Fabric Resources 233 The vport is not operational. The Fabric failed FDISC with a status 234 indicating that it does not have sufficient resources to complete 235 the operation. 236 237 FC_VPORT_FABRIC_LOGOUT - Fabric Logout 238 The vport is not operational. The Fabric has LOGO'd the N_Port_ID 239 associated with the vport. 240 241 FC_VPORT_FABRIC_REJ_WWN - Fabric Rejected WWN 242 The vport is not operational. The Fabric failed FDISC with a status 243 indicating that the WWN's are not valid. 244 245 FC_VPORT_FAILED - VPort Failed 246 The vport is not operational. This is a catchall for all other 247 error conditions. 248 249 250 The following state table indicates the different state transitions: 251 252 State Event New State 253 -------------------------------------------------------------------- 254 n/a Initialization Unknown 255 Unknown: Link Down Linkdown 256 Link Up & Loop No Fabric Support 257 Link Up & no Fabric No Fabric Support 258 Link Up & FLOGI response No Fabric Support 259 indicates no NPIV support 260 Link Up & FDISC being sent Initializing 261 Disable request Disable 262 Linkdown: Link Up Unknown 263 Initializing: FDISC ACC Active 264 FDISC LS_RJT w/ no resources No Fabric Resources 265 FDISC LS_RJT w/ invalid Fabric Rejected WWN 266 pname or invalid nport_id 267 FDISC LS_RJT failed for Vport Failed 268 other reasons 269 Link Down Linkdown 270 Disable request Disable 271 Disable: Enable request Unknown 272 Active: LOGO received from fabric Fabric Logout 273 Link Down Linkdown 274 Disable request Disable 275 Fabric Logout: Link still up Unknown 276 277 The following 4 error states all have the same transitions: 278 No Fabric Support: 279 No Fabric Resources: 280 Fabric Rejected WWN: 281 Vport Failed: 282 Disable request Disable 283 Link goes down Linkdown 284 285 286 Transport <-> LLDD Interfaces : 287 ------------------------------- 288 289 Vport support by LLDD: 290 291 The LLDD indicates support for vports by supplying a vport_create() 292 function in the transport template. The presense of this function will 293 cause the creation of the new attributes on the fc_host. As part of 294 the physical port completing its initialization relative to the 295 transport, it should set the max_npiv_vports attribute to indicate the 296 maximum number of vports the driver and/or adapter supports. 297 298 299 Vport Creation: 300 301 The LLDD vport_create() syntax is: 302 303 int vport_create(struct fc_vport *vport, bool disable) 304 305 where: 306 vport: Is the newly allocated vport object 307 disable: If "true", the vport is to be created in a disabled stated. 308 If "false", the vport is to be enabled upon creation. 309 310 When a request is made to create a new vport (via sgio/netlink, or the 311 vport_create fc_host attribute), the transport will validate that the LLDD 312 can support another vport (e.g. max_npiv_vports > npiv_vports_inuse). 313 If not, the create request will be failed. If space remains, the transport 314 will increment the vport count, create the vport object, and then call the 315 LLDD's vport_create() function with the newly allocated vport object. 316 317 As mentioned above, vport creation is divided into two parts: 318 - Creation with the kernel and LLDD. This means all transport and 319 driver data structures are built up, and device objects created. 320 This is equivalent to a driver "attach" on an adapter, which is 321 independent of the adapter's link state. 322 - Instantiation of the vport on the FC link via ELS traffic, etc. 323 This is equivalent to a "link up" and successfull link initialization. 324 325 The LLDD's vport_create() function will not synchronously wait for both 326 parts to be fully completed before returning. It must validate that the 327 infrastructure exists to support NPIV, and complete the first part of 328 vport creation (data structure build up) before returning. We do not 329 hinge vport_create() on the link-side operation mainly because: 330 - The link may be down. It is not a failure if it is. It simply 331 means the vport is in an inoperable state until the link comes up. 332 This is consistent with the link bouncing post vport creation. 333 - The vport may be created in a disabled state. 334 - This is consistent with a model where: the vport equates to a 335 FC adapter. The vport_create is synonymous with driver attachment 336 to the adapter, which is independent of link state. 337 338 Note: special error codes have been defined to delineate infrastructure 339 failure cases for quicker resolution. 340 341 The expected behavior for the LLDD's vport_create() function is: 342 - Validate Infrastructure: 343 - If the driver or adapter cannot support another vport, whether 344 due to improper firmware, (a lie about) max_npiv, or a lack of 345 some other resource - return VPCERR_UNSUPPORTED. 346 - If the driver validates the WWN's against those already active on 347 the adapter and detects an overlap - return VPCERR_BAD_WWN. 348 - If the driver detects the topology is loop, non-fabric, or the 349 FLOGI did not support NPIV - return VPCERR_NO_FABRIC_SUPP. 350 - Allocate data structures. If errors are encountered, such as out 351 of memory conditions, return the respective negative Exxx error code. 352 - If the role is FCP Initiator, the LLDD is to : 353 - Call scsi_host_alloc() to allocate a scsi_host for the vport. 354 - Call scsi_add_host(new_shost, &vport->dev) to start the scsi_host 355 and bind it as a child of the vport device. 356 - Initializes the fc_host attribute values. 357 - Kick of further vport state transitions based on the disable flag and 358 link state - and return success (zero). 359 360 LLDD Implementers Notes: 361 - It is suggested that there be a different fc_function_templates for 362 the physical port and the virtual port. The physical port's template 363 would have the vport_create, vport_delete, and vport_disable functions, 364 while the vports would not. 365 - It is suggested that there be different scsi_host_templates 366 for the physical port and virtual port. Likely, there are driver 367 attributes, embedded into the scsi_host_template, that are applicable 368 for the physical port only (link speed, topology setting, etc). This 369 ensures that the attributes are applicable to the respective scsi_host. 370 371 372 Vport Disable/Enable: 373 374 The LLDD vport_disable() syntax is: 375 376 int vport_disable(struct fc_vport *vport, bool disable) 377 378 where: 379 vport: Is vport to to be enabled or disabled 380 disable: If "true", the vport is to be disabled. 381 If "false", the vport is to be enabled. 382 383 When a request is made to change the disabled state on a vport, the 384 transport will validate the request against the existing vport state. 385 If the request is to disable and the vport is already disabled, the 386 request will fail. Similarly, if the request is to enable, and the 387 vport is not in a disabled state, the request will fail. If the request 388 is valid for the vport state, the transport will call the LLDD to 389 change the vport's state. 390 391 Within the LLDD, if a vport is disabled, it remains instantiated with 392 the kernel and LLDD, but it is not active or visible on the FC link in 393 any way. (see Vport Creation and the 2 part instantiation discussion). 394 The vport will remain in this state until it is deleted or re-enabled. 395 When enabling a vport, the LLDD reinstantiates the vport on the FC 396 link - essentially restarting the LLDD statemachine (see Vport States 397 above). 398 399 400 Vport Deletion: 401 402 The LLDD vport_delete() syntax is: 403 404 int vport_delete(struct fc_vport *vport) 405 406 where: 407 vport: Is vport to delete 408 409 When a request is made to delete a vport (via sgio/netlink, or via the 410 fc_host or fc_vport vport_delete attributes), the transport will call 411 the LLDD to terminate the vport on the FC link, and teardown all other 412 datastructures and references. If the LLDD completes successfully, 413 the transport will teardown the vport objects and complete the vport 414 removal. If the LLDD delete request fails, the vport object will remain, 415 but will be in an indeterminate state. 416 417 Within the LLDD, the normal code paths for a scsi_host teardown should 418 be followed. E.g. If the vport has a FCP Initiator role, the LLDD 419 will call fc_remove_host() for the vports scsi_host, followed by 420 scsi_remove_host() and scsi_host_put() for the vports scsi_host. 421 422 423 Other: 424 fc_host port_type attribute: 425 There is a new fc_host port_type value - FC_PORTTYPE_NPIV. This value 426 must be set on all vport-based fc_hosts. Normally, on a physical port, 427 the port_type attribute would be set to NPORT, NLPORT, etc based on the 428 topology type and existence of the fabric. As this is not applicable to 429 a vport, it makes more sense to report the FC mechanism used to create 430 the vport. 431 432 Driver unload: 433 FC drivers are required to call fc_remove_host() prior to calling 434 scsi_remove_host(). This allows the fc_host to tear down all remote 435 ports prior the scsi_host being torn down. The fc_remove_host() call 436 was updated to remove all vports for the fc_host as well. 437 438 439 Credits 440 ======= 441 The following people have contributed to this document: 442 443 444 445 446 447 448 James Smart 449 james.smart[AT]emulex[DOT]com