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| -rw-r--r-- | include/xen/interface/io/vscsiif.h | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/include/xen/interface/io/vscsiif.h b/include/xen/interface/io/vscsiif.h new file mode 100644 index 000000000000..d07d7aca8d1c --- /dev/null +++ b/include/xen/interface/io/vscsiif.h @@ -0,0 +1,229 @@ +/****************************************************************************** + * vscsiif.h + * + * Based on the blkif.h code. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to + * deal in the Software without restriction, including without limitation the + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + * + * 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"). + * + * 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. + */ + +/* 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). + */ +#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 + +struct scsiif_request_segment { + grant_ref_t gref; + uint16_t offset; + uint16_t length; +}; + +#define VSCSIIF_SG_PER_PAGE (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]; +}; + +DEFINE_RING_TYPES(vscsiif, struct vscsiif_request, struct vscsiif_response); + +#endif /*__XEN__PUBLIC_IO_SCSI_H__*/ |