Re: [Qemu-devel] Re: [PATCH 24/26] Implement PAPR virtual SCSI interface (ibmvscsi)

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/16/2011 11:41 AM, Alexander Graf wrote:
>> new file mode 100644
>> index 0000000..9d55fc4
>> --- /dev/null
>> +++ b/hw/srp.h
>> @@ -0,0 +1,241 @@
>> +/*
>> + * Copyright (c) 2005 Cisco Systems.  All rights reserved.
>> + *
>> + * This software is available to you under a choice of one of two
>> + * licenses.  You may choose to be licensed under the terms of the GNU
>> + * General Public License (GPL) Version 2, available from the file
>> + * COPYING in the main directory of this source tree, or the
>> + * OpenIB.org BSD license below:
>> + *
>> + *     Redistribution and use in source and binary forms, with or
>> + *     without modification, are permitted provided that the following
>> + *     conditions are met:
>> + *
>> + *      - Redistributions of source code must retain the above
>> + *        copyright notice, this list of conditions and the following
>> + *        disclaimer.
>> + *
>> + *      - Redistributions in binary form must reproduce the above
>> + *        copyright notice, this list of conditions and the following
>> + *        disclaimer in the documentation and/or other materials
>> + *        provided with the distribution.
>> + *
>> + * 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.
>> + *
>> + * $Id$
>> + */
>> +
>> +#ifndef SCSI_SRP_H
>> +#define SCSI_SRP_H
>> +
>> +/*
>> + * Structures and constants for the SCSI RDMA Protocol (SRP) as
>> + * defined by the INCITS T10 committee.  This file was written using
>> + * draft Revision 16a of the SRP standard.
>> + */
>> +
>> +enum {
>> +
>> +    SRP_LOGIN_REQ = 0x00,
>> +    SRP_TSK_MGMT  = 0x01,
>> +    SRP_CMD       = 0x02,
>> +    SRP_I_LOGOUT  = 0x03,
>> +    SRP_LOGIN_RSP = 0xc0,
>> +    SRP_RSP       = 0xc1,
>> +    SRP_LOGIN_REJ = 0xc2,
>> +    SRP_T_LOGOUT  = 0x80,
>> +    SRP_CRED_REQ  = 0x81,
>> +    SRP_AER_REQ   = 0x82,
>> +    SRP_CRED_RSP  = 0x41,
>> +    SRP_AER_RSP   = 0x42
>> +};
>> +
>> +enum {
>> +    SRP_BUF_FORMAT_DIRECT   = 1<<  1,
>> +    SRP_BUF_FORMAT_INDIRECT = 1<<  2
>> +};
>> +
>> +enum {
>> +    SRP_NO_DATA_DESC       = 0,
>> +    SRP_DATA_DESC_DIRECT   = 1,
>> +    SRP_DATA_DESC_INDIRECT = 2
>> +};
>> +
>> +enum {
>> +    SRP_TSK_ABORT_TASK     = 0x01,
>> +    SRP_TSK_ABORT_TASK_SET = 0x02,
>> +    SRP_TSK_CLEAR_TASK_SET = 0x04,
>> +    SRP_TSK_LUN_RESET      = 0x08,
>> +    SRP_TSK_CLEAR_ACA      = 0x40
>> +};
>> +
>> +enum srp_login_rej_reason {
>> +    SRP_LOGIN_REJ_UNABLE_ESTABLISH_CHANNEL   = 0x00010000,
>> +    SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES     = 0x00010001,
>> +    SRP_LOGIN_REJ_REQ_IT_IU_LENGTH_TOO_LARGE = 0x00010002,
>> +    SRP_LOGIN_REJ_UNABLE_ASSOCIATE_CHANNEL   = 0x00010003,
>> +    SRP_LOGIN_REJ_UNSUPPORTED_DESCRIPTOR_FMT = 0x00010004,
>> +    SRP_LOGIN_REJ_MULTI_CHANNEL_UNSUPPORTED  = 0x00010005,
>> +    SRP_LOGIN_REJ_CHANNEL_LIMIT_REACHED      = 0x00010006
>> +};
>> +
>> +enum {
>> +    SRP_REV10_IB_IO_CLASS  = 0xff00,
>> +    SRP_REV16A_IB_IO_CLASS = 0x0100
>> +};
>> +
>> +struct srp_direct_buf {
>> +    uint64_t    va;
>> +    uint32_t    key;
>> +    uint32_t    len;
>> +};
>> +
>> +/*
>> + * We need the packed attribute because the SRP spec puts the list of
>> + * descriptors at an offset of 20, which is not aligned to the size of
>> + * struct srp_direct_buf.  The whole structure must be packed to avoid
>> + * having the 20-byte structure padded to 24 bytes on 64-bit 
>> architectures.
>> + */
>> +struct srp_indirect_buf {
>> +    struct srp_direct_buf    table_desc;
>> +    uint32_t                 len;
>> +    struct srp_direct_buf    desc_list[0];
>> +} __attribute__((packed));
>> +
>> +enum {
>> +    SRP_MULTICHAN_SINGLE = 0,
>> +    SRP_MULTICHAN_MULTI  = 1
>> +};
>> +
>> +struct srp_login_req {
>> +    uint8_t    opcode;
>> +    uint8_t    reserved1[7];
>> +    uint64_t   tag;
>> +    uint32_t   req_it_iu_len;
>> +    uint8_t    reserved2[4];
>> +    uint16_t   req_buf_fmt;
>> +    uint8_t    req_flags;
>> +    uint8_t    reserved3[5];
>> +    uint8_t    initiator_port_id[16];
>> +    uint8_t    target_port_id[16];
>> +};
>> +
>> +/*
>> + * The SRP spec defines the size of the LOGIN_RSP structure to be 52
>> + * bytes, so it needs to be packed to avoid having it padded to 56
>> + * bytes on 64-bit architectures.
>> + */
>> +struct srp_login_rsp {
>> +    uint8_t    opcode;
>> +    uint8_t    reserved1[3];
>> +    uint32_t   req_lim_delta;
>> +    uint64_t   tag;
>> +    uint32_t   max_it_iu_len;
>> +    uint32_t   max_ti_iu_len;
>> +    uint16_t   buf_fmt;
>> +    uint8_t    rsp_flags;
>> +    uint8_t    reserved2[25];
>> +} __attribute__((packed));
>> +
>> +struct srp_login_rej {
>> +    uint8_t    opcode;
>> +    uint8_t    reserved1[3];
>> +    uint32_t   reason;
>> +    uint64_t   tag;
>> +    uint8_t    reserved2[8];
>> +    uint16_t   buf_fmt;
>> +    uint8_t    reserved3[6];
>> +};
> diff --git a/hw/srp.h b/hw/srp.h
>
> Why isn't this one packed? And the ones below?

It's naturally aligned.  There's no need to pack things that are 
naturally aligned (structure size is a multiple of 8 and each type 
starts at an offset that's a multiple of it's size).

Regards,

Anthony Liguori