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linuxdebug/include/xen/interface/io/vscsiif.h

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/* 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__*/
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