1/*
2 * sd_dif.c - SCSI Data Integrity Field
3 *
4 * Copyright (C) 2007, 2008 Oracle Corporation
5 * Written by: Martin K. Petersen <martin.petersen@oracle.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License version
9 * 2 as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; see the file COPYING.  If not, write to
18 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
19 * USA.
20 *
21 */
22
23#include <linux/blkdev.h>
24#include <linux/t10-pi.h>
25
26#include <scsi/scsi.h>
27#include <scsi/scsi_cmnd.h>
28#include <scsi/scsi_dbg.h>
29#include <scsi/scsi_device.h>
30#include <scsi/scsi_driver.h>
31#include <scsi/scsi_eh.h>
32#include <scsi/scsi_host.h>
33#include <scsi/scsi_ioctl.h>
34#include <scsi/scsicam.h>
35
36#include "sd.h"
37
38/*
39 * Configure exchange of protection information between OS and HBA.
40 */
41void sd_dif_config_host(struct scsi_disk *sdkp)
42{
43	struct scsi_device *sdp = sdkp->device;
44	struct gendisk *disk = sdkp->disk;
45	u8 type = sdkp->protection_type;
46	struct blk_integrity bi;
47	int dif, dix;
48
49	dif = scsi_host_dif_capable(sdp->host, type);
50	dix = scsi_host_dix_capable(sdp->host, type);
51
52	if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
53		dif = 0; dix = 1;
54	}
55
56	if (!dix)
57		return;
58
59	memset(&bi, 0, sizeof(bi));
60
61	/* Enable DMA of protection information */
62	if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP) {
63		if (type == SD_DIF_TYPE3_PROTECTION)
64			bi.profile = &t10_pi_type3_ip;
65		else
66			bi.profile = &t10_pi_type1_ip;
67
68		bi.flags |= BLK_INTEGRITY_IP_CHECKSUM;
69	} else
70		if (type == SD_DIF_TYPE3_PROTECTION)
71			bi.profile = &t10_pi_type3_crc;
72		else
73			bi.profile = &t10_pi_type1_crc;
74
75	bi.tuple_size = sizeof(struct t10_pi_tuple);
76	sd_printk(KERN_NOTICE, sdkp,
77		  "Enabling DIX %s protection\n", bi.profile->name);
78
79	if (dif && type) {
80		bi.flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
81
82		if (!sdkp->ATO)
83			goto out;
84
85		if (type == SD_DIF_TYPE3_PROTECTION)
86			bi.tag_size = sizeof(u16) + sizeof(u32);
87		else
88			bi.tag_size = sizeof(u16);
89
90		sd_printk(KERN_NOTICE, sdkp, "DIF application tag size %u\n",
91			  bi.tag_size);
92	}
93
94out:
95	blk_integrity_register(disk, &bi);
96}
97
98/*
99 * The virtual start sector is the one that was originally submitted
100 * by the block layer.	Due to partitioning, MD/DM cloning, etc. the
101 * actual physical start sector is likely to be different.  Remap
102 * protection information to match the physical LBA.
103 *
104 * From a protocol perspective there's a slight difference between
105 * Type 1 and 2.  The latter uses 32-byte CDBs exclusively, and the
106 * reference tag is seeded in the CDB.  This gives us the potential to
107 * avoid virt->phys remapping during write.  However, at read time we
108 * don't know whether the virt sector is the same as when we wrote it
109 * (we could be reading from real disk as opposed to MD/DM device.  So
110 * we always remap Type 2 making it identical to Type 1.
111 *
112 * Type 3 does not have a reference tag so no remapping is required.
113 */
114void sd_dif_prepare(struct scsi_cmnd *scmd)
115{
116	const int tuple_sz = sizeof(struct t10_pi_tuple);
117	struct bio *bio;
118	struct scsi_disk *sdkp;
119	struct t10_pi_tuple *pi;
120	u32 phys, virt;
121
122	sdkp = scsi_disk(scmd->request->rq_disk);
123
124	if (sdkp->protection_type == SD_DIF_TYPE3_PROTECTION)
125		return;
126
127	phys = scsi_prot_ref_tag(scmd);
128
129	__rq_for_each_bio(bio, scmd->request) {
130		struct bio_integrity_payload *bip = bio_integrity(bio);
131		struct bio_vec iv;
132		struct bvec_iter iter;
133		unsigned int j;
134
135		/* Already remapped? */
136		if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
137			break;
138
139		virt = bip_get_seed(bip) & 0xffffffff;
140
141		bip_for_each_vec(iv, bip, iter) {
142			pi = kmap_atomic(iv.bv_page) + iv.bv_offset;
143
144			for (j = 0; j < iv.bv_len; j += tuple_sz, pi++) {
145
146				if (be32_to_cpu(pi->ref_tag) == virt)
147					pi->ref_tag = cpu_to_be32(phys);
148
149				virt++;
150				phys++;
151			}
152
153			kunmap_atomic(pi);
154		}
155
156		bip->bip_flags |= BIP_MAPPED_INTEGRITY;
157	}
158}
159
160/*
161 * Remap physical sector values in the reference tag to the virtual
162 * values expected by the block layer.
163 */
164void sd_dif_complete(struct scsi_cmnd *scmd, unsigned int good_bytes)
165{
166	const int tuple_sz = sizeof(struct t10_pi_tuple);
167	struct scsi_disk *sdkp;
168	struct bio *bio;
169	struct t10_pi_tuple *pi;
170	unsigned int j, intervals;
171	u32 phys, virt;
172
173	sdkp = scsi_disk(scmd->request->rq_disk);
174
175	if (sdkp->protection_type == SD_DIF_TYPE3_PROTECTION || good_bytes == 0)
176		return;
177
178	intervals = good_bytes / scsi_prot_interval(scmd);
179	phys = scsi_prot_ref_tag(scmd);
180
181	__rq_for_each_bio(bio, scmd->request) {
182		struct bio_integrity_payload *bip = bio_integrity(bio);
183		struct bio_vec iv;
184		struct bvec_iter iter;
185
186		virt = bip_get_seed(bip) & 0xffffffff;
187
188		bip_for_each_vec(iv, bip, iter) {
189			pi = kmap_atomic(iv.bv_page) + iv.bv_offset;
190
191			for (j = 0; j < iv.bv_len; j += tuple_sz, pi++) {
192
193				if (intervals == 0) {
194					kunmap_atomic(pi);
195					return;
196				}
197
198				if (be32_to_cpu(pi->ref_tag) == phys)
199					pi->ref_tag = cpu_to_be32(virt);
200
201				virt++;
202				phys++;
203				intervals--;
204			}
205
206			kunmap_atomic(pi);
207		}
208	}
209}
210
211