diff options
Diffstat (limited to 'include/xen/interface/io/vscsiif.h')
| -rw-r--r-- | include/xen/interface/io/vscsiif.h | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/include/xen/interface/io/vscsiif.h b/include/xen/interface/io/vscsiif.h new file mode 100644 index 0000000000..7ea4dc9611 --- /dev/null +++ b/include/xen/interface/io/vscsiif.h @@ -0,0 +1,337 @@ +/* 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 1 + +/* + * 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 2 + +/* + * Request a device reset of the specified target (channel and id). + */ +#define VSCSIIF_ACT_SCSI_RESET 3 + +/* + * 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 4 + +/* + * 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 26 + +/* + * 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 16 +#define VSCSIIF_SENSE_BUFFERSIZE 96 +#define VSCSIIF_PAGE_SIZE 4096 + +struct scsiif_request_segment { + grant_ref_t gref; + uint16_t offset; + uint16_t length; +}; + +#define VSCSIIF_SG_PER_PAGE (VSCSIIF_PAGE_SIZE / \ + sizeof(struct scsiif_request_segment)) + +/* Size of one request is 252 bytes */ +struct vscsiif_request { + uint16_t rqid; /* private guest value, echoed in resp */ + uint8_t act; /* command between backend and frontend */ + uint8_t cmd_len; /* valid CDB bytes */ + + uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE]; /* the CDB */ + uint16_t timeout_per_command; /* deprecated */ + uint16_t channel, id, lun; /* (virtual) device specification */ + uint16_t ref_rqid; /* command abort reference */ + uint8_t sc_data_direction; /* for DMA_TO_DEVICE(1) + DMA_FROM_DEVICE(2) + DMA_NONE(3) requests */ + uint8_t nr_segments; /* Number of pieces of scatter-gather */ +/* + * flag in nr_segments: SG elements via grant page + * + * If VSCSIIF_SG_GRANT is set, the low 7 bits of nr_segments specify the number + * of grant pages containing SG elements. Usable if "feature-sg-grant" set. + */ +#define VSCSIIF_SG_GRANT 0x80 + + struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE]; + uint32_t reserved[3]; +}; + +/* Size of one response is 252 bytes */ +struct vscsiif_response { + uint16_t rqid; /* identifies request */ + uint8_t padding; + uint8_t sense_len; + uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE]; + int32_t rslt; + uint32_t residual_len; /* request bufflen - + return the value from physical device */ + uint32_t reserved[36]; +}; + +/* SCSI I/O status from vscsiif_response->rslt */ +#define XEN_VSCSIIF_RSLT_STATUS(x) ((x) & 0x00ff) + +/* Host I/O status from vscsiif_response->rslt */ +#define XEN_VSCSIIF_RSLT_HOST(x) (((x) & 0x00ff0000) >> 16) +#define XEN_VSCSIIF_RSLT_HOST_OK 0 +/* Couldn't connect before timeout */ +#define XEN_VSCSIIF_RSLT_HOST_NO_CONNECT 1 +/* Bus busy through timeout */ +#define XEN_VSCSIIF_RSLT_HOST_BUS_BUSY 2 +/* Timed out for other reason */ +#define XEN_VSCSIIF_RSLT_HOST_TIME_OUT 3 +/* Bad target */ +#define XEN_VSCSIIF_RSLT_HOST_BAD_TARGET 4 +/* Abort for some other reason */ +#define XEN_VSCSIIF_RSLT_HOST_ABORT 5 +/* Parity error */ +#define XEN_VSCSIIF_RSLT_HOST_PARITY 6 +/* Internal error */ +#define XEN_VSCSIIF_RSLT_HOST_ERROR 7 +/* Reset by somebody */ +#define XEN_VSCSIIF_RSLT_HOST_RESET 8 +/* Unexpected interrupt */ +#define XEN_VSCSIIF_RSLT_HOST_BAD_INTR 9 +/* Force command past mid-layer */ +#define XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH 10 +/* Retry requested */ +#define XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR 11 +/* Hidden retry requested */ +#define XEN_VSCSIIF_RSLT_HOST_IMM_RETRY 12 +/* Requeue command requested */ +#define XEN_VSCSIIF_RSLT_HOST_REQUEUE 13 +/* Transport error disrupted I/O */ +#define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED 14 +/* Transport class fastfailed */ +#define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST 15 +/* Permanent target failure */ +#define XEN_VSCSIIF_RSLT_HOST_TARGET_FAILURE 16 +/* Permanent nexus failure on path */ +#define XEN_VSCSIIF_RSLT_HOST_NEXUS_FAILURE 17 +/* Space allocation on device failed */ +#define XEN_VSCSIIF_RSLT_HOST_ALLOC_FAILURE 18 +/* Medium error */ +#define XEN_VSCSIIF_RSLT_HOST_MEDIUM_ERROR 19 +/* Transport marginal errors */ +#define XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL 20 + +/* Result values of reset operations */ +#define XEN_VSCSIIF_RSLT_RESET_SUCCESS 0x2002 +#define XEN_VSCSIIF_RSLT_RESET_FAILED 0x2003 + +DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); + + +#endif /*__XEN__PUBLIC_IO_SCSI_H__*/ |