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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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