/* SPDX-License-Identifier: MIT */ /****************************************************************************** * vscsiif.h * * Based on the blkif.h code. * * Copyright(c) FUJITSU Limited 2008. */ #ifndef __XEN__PUBLIC_IO_SCSI_H__ #define __XEN__PUBLIC_IO_SCSI_H__ #include "ring.h" #include "../grant_table.h" /* * Feature and Parameter Negotiation * ================================= * The two halves of a Xen pvSCSI driver utilize nodes within the XenStore to * communicate capabilities and to negotiate operating parameters. This * section enumerates these nodes which reside in the respective front and * backend portions of the XenStore, following the XenBus convention. * * Any specified default value is in effect if the corresponding XenBus node * is not present in the XenStore. * * XenStore nodes in sections marked "PRIVATE" are solely for use by the * driver side whose XenBus tree contains them. * ***************************************************************************** * Backend XenBus Nodes ***************************************************************************** * *------------------ Backend Device Identification (PRIVATE) ------------------ * * p-devname * Values: string * * A free string used to identify the physical device (e.g. a disk name). * * p-dev * Values: string * * A string specifying the backend device: either a 4-tuple "h:c:t:l" * (host, controller, target, lun, all integers), or a WWN (e.g. * "naa.60014054ac780582:0"). * * v-dev * Values: string * * A string specifying the frontend device in form of a 4-tuple "h:c:t:l" * (host, controller, target, lun, all integers). * *--------------------------------- Features --------------------------------- * * feature-sg-grant * Values: unsigned [VSCSIIF_SG_TABLESIZE...65535] * Default Value: 0 * * Specifies the maximum number of scatter/gather elements in grant pages * supported. If not set, the backend supports up to VSCSIIF_SG_TABLESIZE * SG elements specified directly in the request. * ***************************************************************************** * Frontend XenBus Nodes ***************************************************************************** * *----------------------- Request Transport Parameters ----------------------- * * event-channel * Values: unsigned * * The identifier of the Xen event channel used to signal activity * in the ring buffer. * * ring-ref * Values: unsigned * * The Xen grant reference granting permission for the backend to map * the sole page in a single page sized ring buffer. * * protocol * Values: string (XEN_IO_PROTO_ABI_*) * Default Value: XEN_IO_PROTO_ABI_NATIVE * * The machine ABI rules governing the format of all ring request and * response structures. */ /* * Xenstore format in practice * =========================== * * The backend driver uses a single_host:many_devices notation to manage domU * devices. Everything is stored in /local/domain/<backend_domid>/backend/vscsi/. * The xenstore layout looks like this (dom0 is assumed to be the backend_domid): * * <domid>/<vhost>/feature-host = "0" * <domid>/<vhost>/frontend = "/local/domain/<domid>/device/vscsi/0" * <domid>/<vhost>/frontend-id = "<domid>" * <domid>/<vhost>/online = "1" * <domid>/<vhost>/state = "4" * <domid>/<vhost>/vscsi-devs/dev-0/p-dev = "8:0:2:1" or "naa.wwn:lun" * <domid>/<vhost>/vscsi-devs/dev-0/state = "4" * <domid>/<vhost>/vscsi-devs/dev-0/v-dev = "0:0:0:0" * <domid>/<vhost>/vscsi-devs/dev-1/p-dev = "8:0:2:2" * <domid>/<vhost>/vscsi-devs/dev-1/state = "4" * <domid>/<vhost>/vscsi-devs/dev-1/v-dev = "0:0:1:0" * * The frontend driver maintains its state in * /local/domain/<domid>/device/vscsi/. * * <vhost>/backend = "/local/domain/0/backend/vscsi/<domid>/<vhost>" * <vhost>/backend-id = "0" * <vhost>/event-channel = "20" * <vhost>/ring-ref = "43" * <vhost>/state = "4" * <vhost>/vscsi-devs/dev-0/state = "4" * <vhost>/vscsi-devs/dev-1/state = "4" * * In addition to the entries for backend and frontend these flags are stored * for the toolstack: * * <domid>/<vhost>/vscsi-devs/dev-1/p-devname = "/dev/$device" * <domid>/<vhost>/libxl_ctrl_index = "0" * * * Backend/frontend protocol * ========================= * * To create a vhost along with a device: * <domid>/<vhost>/feature-host = "0" * <domid>/<vhost>/frontend = "/local/domain/<domid>/device/vscsi/0" * <domid>/<vhost>/frontend-id = "<domid>" * <domid>/<vhost>/online = "1" * <domid>/<vhost>/state = "1" * <domid>/<vhost>/vscsi-devs/dev-0/p-dev = "8:0:2:1" * <domid>/<vhost>/vscsi-devs/dev-0/state = "1" * <domid>/<vhost>/vscsi-devs/dev-0/v-dev = "0:0:0:0" * Wait for <domid>/<vhost>/state + <domid>/<vhost>/vscsi-devs/dev-0/state become 4 * * To add another device to a vhost: * <domid>/<vhost>/state = "7" * <domid>/<vhost>/vscsi-devs/dev-1/p-dev = "8:0:2:2" * <domid>/<vhost>/vscsi-devs/dev-1/state = "1" * <domid>/<vhost>/vscsi-devs/dev-1/v-dev = "0:0:1:0" * Wait for <domid>/<vhost>/state + <domid>/<vhost>/vscsi-devs/dev-1/state become 4 * * To remove a device from a vhost: * <domid>/<vhost>/state = "7" * <domid>/<vhost>/vscsi-devs/dev-1/state = "5" * Wait for <domid>/<vhost>/state to become 4 * Wait for <domid>/<vhost>/vscsi-devs/dev-1/state become 6 * Remove <domid>/<vhost>/vscsi-devs/dev-1/{state,p-dev,v-dev,p-devname} * Remove <domid>/<vhost>/vscsi-devs/dev-1/ * */ /* Requests from the frontend to the backend */ /* * Request a SCSI operation specified via a CDB in vscsiif_request.cmnd. * The target is specified via channel, id and lun. * * The operation to be performed is specified via a CDB in cmnd[], the length * of the CDB is in cmd_len. sc_data_direction specifies the direction of data * (to the device, from the device, or none at all). * * If data is to be transferred to or from the device the buffer(s) in the * guest memory is/are specified via one or multiple scsiif_request_segment * descriptors each specifying a memory page via a grant_ref_t, a offset into * the page and the length of the area in that page. All scsiif_request_segment * areas concatenated form the resulting data buffer used by the operation. * If the number of scsiif_request_segment areas is not too large (less than * or equal VSCSIIF_SG_TABLESIZE) the areas can be specified directly in the * seg[] array and the number of valid scsiif_request_segment elements is to be * set in nr_segments. * * If "feature-sg-grant" in the Xenstore is set it is possible to specify more * than VSCSIIF_SG_TABLESIZE scsiif_request_segment elements via indirection. * The maximum number of allowed scsiif_request_segment elements is the value * of the "feature-sg-grant" entry from Xenstore. When using indirection the * seg[] array doesn't contain specifications of the data buffers, but * references to scsiif_request_segment arrays, which in turn reference the * data buffers. While nr_segments holds the number of populated seg[] entries * (plus the set VSCSIIF_SG_GRANT bit), the number of scsiif_request_segment * elements referencing the target data buffers is calculated from the lengths * of the seg[] elements (the sum of all valid seg[].length divided by the * size of one scsiif_request_segment structure). The frontend may use a mix of * direct and indirect requests. */ #define VSCSIIF_ACT_SCSI_CDB … /* * Request abort of a running operation for the specified target given by * channel, id, lun and the operation's rqid in ref_rqid. */ #define VSCSIIF_ACT_SCSI_ABORT … /* * Request a device reset of the specified target (channel and id). */ #define VSCSIIF_ACT_SCSI_RESET … /* * Preset scatter/gather elements for a following request. Deprecated. * Keeping the define only to avoid usage of the value "4" for other actions. */ #define VSCSIIF_ACT_SCSI_SG_PRESET … /* * Maximum scatter/gather segments per request. * * Considering balance between allocating at least 16 "vscsiif_request" * structures on one page (4096 bytes) and the number of scatter/gather * elements needed, we decided to use 26 as a magic number. * * If "feature-sg-grant" is set, more scatter/gather elements can be specified * by placing them in one or more (up to VSCSIIF_SG_TABLESIZE) granted pages. * In this case the vscsiif_request seg elements don't contain references to * the user data, but to the SG elements referencing the user data. */ #define VSCSIIF_SG_TABLESIZE … /* * based on Linux kernel 2.6.18, still valid * * Changing these values requires support of multiple protocols via the rings * as "old clients" will blindly use these values and the resulting structure * sizes. */ #define VSCSIIF_MAX_COMMAND_SIZE … #define VSCSIIF_SENSE_BUFFERSIZE … #define VSCSIIF_PAGE_SIZE … struct scsiif_request_segment { … }; #define VSCSIIF_SG_PER_PAGE … /* Size of one request is 252 bytes */ struct vscsiif_request { … }; /* Size of one response is 252 bytes */ struct vscsiif_response { … }; /* SCSI I/O status from vscsiif_response->rslt */ #define XEN_VSCSIIF_RSLT_STATUS(x) … /* Host I/O status from vscsiif_response->rslt */ #define XEN_VSCSIIF_RSLT_HOST(x) … #define XEN_VSCSIIF_RSLT_HOST_OK … /* Couldn't connect before timeout */ #define XEN_VSCSIIF_RSLT_HOST_NO_CONNECT … /* Bus busy through timeout */ #define XEN_VSCSIIF_RSLT_HOST_BUS_BUSY … /* Timed out for other reason */ #define XEN_VSCSIIF_RSLT_HOST_TIME_OUT … /* Bad target */ #define XEN_VSCSIIF_RSLT_HOST_BAD_TARGET … /* Abort for some other reason */ #define XEN_VSCSIIF_RSLT_HOST_ABORT … /* Parity error */ #define XEN_VSCSIIF_RSLT_HOST_PARITY … /* Internal error */ #define XEN_VSCSIIF_RSLT_HOST_ERROR … /* Reset by somebody */ #define XEN_VSCSIIF_RSLT_HOST_RESET … /* Unexpected interrupt */ #define XEN_VSCSIIF_RSLT_HOST_BAD_INTR … /* Force command past mid-layer */ #define XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH … /* Retry requested */ #define XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR … /* Hidden retry requested */ #define XEN_VSCSIIF_RSLT_HOST_IMM_RETRY … /* Requeue command requested */ #define XEN_VSCSIIF_RSLT_HOST_REQUEUE … /* Transport error disrupted I/O */ #define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED … /* Transport class fastfailed */ #define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST … /* Permanent target failure */ #define XEN_VSCSIIF_RSLT_HOST_TARGET_FAILURE … /* Permanent nexus failure on path */ #define XEN_VSCSIIF_RSLT_HOST_NEXUS_FAILURE … /* Space allocation on device failed */ #define XEN_VSCSIIF_RSLT_HOST_ALLOC_FAILURE … /* Medium error */ #define XEN_VSCSIIF_RSLT_HOST_MEDIUM_ERROR … /* Transport marginal errors */ #define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL … /* Result values of reset operations */ #define XEN_VSCSIIF_RSLT_RESET_SUCCESS … #define XEN_VSCSIIF_RSLT_RESET_FAILED … DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); #endif /*__XEN__PUBLIC_IO_SCSI_H__*/
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