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common.h
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26 
27 #ifndef __XEN_BLKIF__BACKEND__COMMON_H__
28 #define __XEN_BLKIF__BACKEND__COMMON_H__
29 
30 #include <linux/module.h>
31 #include <linux/interrupt.h>
32 #include <linux/slab.h>
33 #include <linux/blkdev.h>
34 #include <linux/vmalloc.h>
35 #include <linux/wait.h>
36 #include <linux/io.h>
37 #include <asm/setup.h>
38 #include <asm/pgalloc.h>
39 #include <asm/hypervisor.h>
40 #include <xen/grant_table.h>
41 #include <xen/xenbus.h>
42 #include <xen/interface/io/ring.h>
43 #include <xen/interface/io/blkif.h>
44 #include <xen/interface/io/protocols.h>
45 
46 #define DRV_PFX "xen-blkback:"
47 #define DPRINTK(fmt, args...) \
48  pr_debug(DRV_PFX "(%s:%d) " fmt ".\n", \
49  __func__, __LINE__, ##args)
50 
51 
52 /* Not a real protocol. Used to generate ring structs which contain
53  * the elements common to all protocols only. This way we get a
54  * compiler-checkable way to use common struct elements, so we can
55  * avoid using switch(protocol) in a number of places. */
56 struct blkif_common_request {
57  char dummy;
58 };
59 struct blkif_common_response {
60  char dummy;
61 };
62 
63 struct blkif_x86_32_request_rw {
64  uint8_t nr_segments; /* number of segments */
65  blkif_vdev_t handle; /* only for read/write requests */
66  uint64_t id; /* private guest value, echoed in resp */
67  blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
68  struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
69 } __attribute__((__packed__));
70 
71 struct blkif_x86_32_request_discard {
72  uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
73  blkif_vdev_t _pad1; /* was "handle" for read/write requests */
74  uint64_t id; /* private guest value, echoed in resp */
75  blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
76  uint64_t nr_sectors;
77 } __attribute__((__packed__));
78 
79 struct blkif_x86_32_request {
80  uint8_t operation; /* BLKIF_OP_??? */
81  union {
82  struct blkif_x86_32_request_rw rw;
83  struct blkif_x86_32_request_discard discard;
84  } u;
85 } __attribute__((__packed__));
86 
87 /* i386 protocol version */
88 #pragma pack(push, 4)
89 struct blkif_x86_32_response {
90  uint64_t id; /* copied from request */
91  uint8_t operation; /* copied from request */
92  int16_t status; /* BLKIF_RSP_??? */
93 };
94 #pragma pack(pop)
95 /* x86_64 protocol version */
96 
97 struct blkif_x86_64_request_rw {
98  uint8_t nr_segments; /* number of segments */
99  blkif_vdev_t handle; /* only for read/write requests */
100  uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */
101  uint64_t id;
102  blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
103  struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
104 } __attribute__((__packed__));
105 
106 struct blkif_x86_64_request_discard {
107  uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
108  blkif_vdev_t _pad1; /* was "handle" for read/write requests */
109  uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
110  uint64_t id;
111  blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
112  uint64_t nr_sectors;
113 } __attribute__((__packed__));
114 
115 struct blkif_x86_64_request {
116  uint8_t operation; /* BLKIF_OP_??? */
117  union {
118  struct blkif_x86_64_request_rw rw;
119  struct blkif_x86_64_request_discard discard;
120  } u;
121 } __attribute__((__packed__));
122 
123 struct blkif_x86_64_response {
124  uint64_t __attribute__((__aligned__(8))) id;
125  uint8_t operation; /* copied from request */
126  int16_t status; /* BLKIF_RSP_??? */
127 };
128 
129 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
130  struct blkif_common_response);
131 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
132  struct blkif_x86_32_response);
133 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
134  struct blkif_x86_64_response);
135 
136 union blkif_back_rings {
137  struct blkif_back_ring native;
138  struct blkif_common_back_ring common;
139  struct blkif_x86_32_back_ring x86_32;
140  struct blkif_x86_64_back_ring x86_64;
141 };
142 
143 enum blkif_protocol {
144  BLKIF_PROTOCOL_NATIVE = 1,
145  BLKIF_PROTOCOL_X86_32 = 2,
146  BLKIF_PROTOCOL_X86_64 = 3,
147 };
148 
149 struct xen_vbd {
150  /* What the domain refers to this vbd as. */
151  blkif_vdev_t handle;
152  /* Non-zero -> read-only */
153  unsigned char readonly;
154  /* VDISK_xxx */
155  unsigned char type;
156  /* phys device that this vbd maps to. */
157  u32 pdevice;
158  struct block_device *bdev;
159  /* Cached size parameter. */
160  sector_t size;
161  unsigned int flush_support:1;
162  unsigned int discard_secure:1;
163 };
164 
165 struct backend_info;
166 
167 struct xen_blkif {
168  /* Unique identifier for this interface. */
169  domid_t domid;
170  unsigned int handle;
171  /* Physical parameters of the comms window. */
172  unsigned int irq;
173  /* Comms information. */
174  enum blkif_protocol blk_protocol;
175  union blkif_back_rings blk_rings;
176  void *blk_ring;
177  /* The VBD attached to this interface. */
178  struct xen_vbd vbd;
179  /* Back pointer to the backend_info. */
180  struct backend_info *be;
181  /* Private fields. */
182  spinlock_t blk_ring_lock;
183  atomic_t refcnt;
184 
185  wait_queue_head_t wq;
186  /* for barrier (drain) requests */
187  struct completion drain_complete;
188  atomic_t drain;
189  /* One thread per one blkif. */
190  struct task_struct *xenblkd;
191  unsigned int waiting_reqs;
192 
193  /* statistics */
194  unsigned long st_print;
195  int st_rd_req;
196  int st_wr_req;
197  int st_oo_req;
198  int st_f_req;
199  int st_ds_req;
200  int st_rd_sect;
201  int st_wr_sect;
202 
203  wait_queue_head_t waiting_to_free;
204 };
205 
206 
207 #define vbd_sz(_v) ((_v)->bdev->bd_part ? \
208  (_v)->bdev->bd_part->nr_sects : \
209  get_capacity((_v)->bdev->bd_disk))
210 
211 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
212 #define xen_blkif_put(_b) \
213  do { \
214  if (atomic_dec_and_test(&(_b)->refcnt)) \
215  wake_up(&(_b)->waiting_to_free);\
216  } while (0)
217 
218 struct phys_req {
219  unsigned short dev;
220  blkif_sector_t nr_sects;
221  struct block_device *bdev;
222  blkif_sector_t sector_number;
223 };
224 int xen_blkif_interface_init(void);
225 
226 int xen_blkif_xenbus_init(void);
227 
228 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
229 int xen_blkif_schedule(void *arg);
230 
231 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
232  struct backend_info *be, int state);
233 
234 int xen_blkbk_barrier(struct xenbus_transaction xbt,
235  struct backend_info *be, int state);
236 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
237 
238 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
239  struct blkif_x86_32_request *src)
240 {
241  int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
242  dst->operation = src->operation;
243  switch (src->operation) {
244  case BLKIF_OP_READ:
245  case BLKIF_OP_WRITE:
246  case BLKIF_OP_WRITE_BARRIER:
247  case BLKIF_OP_FLUSH_DISKCACHE:
248  dst->u.rw.nr_segments = src->u.rw.nr_segments;
249  dst->u.rw.handle = src->u.rw.handle;
250  dst->u.rw.id = src->u.rw.id;
251  dst->u.rw.sector_number = src->u.rw.sector_number;
252  barrier();
253  if (n > dst->u.rw.nr_segments)
254  n = dst->u.rw.nr_segments;
255  for (i = 0; i < n; i++)
256  dst->u.rw.seg[i] = src->u.rw.seg[i];
257  break;
258  case BLKIF_OP_DISCARD:
259  dst->u.discard.flag = src->u.discard.flag;
260  dst->u.discard.id = src->u.discard.id;
261  dst->u.discard.sector_number = src->u.discard.sector_number;
262  dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
263  break;
264  default:
265  break;
266  }
267 }
268 
269 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
270  struct blkif_x86_64_request *src)
271 {
272  int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
273  dst->operation = src->operation;
274  switch (src->operation) {
275  case BLKIF_OP_READ:
276  case BLKIF_OP_WRITE:
277  case BLKIF_OP_WRITE_BARRIER:
278  case BLKIF_OP_FLUSH_DISKCACHE:
279  dst->u.rw.nr_segments = src->u.rw.nr_segments;
280  dst->u.rw.handle = src->u.rw.handle;
281  dst->u.rw.id = src->u.rw.id;
282  dst->u.rw.sector_number = src->u.rw.sector_number;
283  barrier();
284  if (n > dst->u.rw.nr_segments)
285  n = dst->u.rw.nr_segments;
286  for (i = 0; i < n; i++)
287  dst->u.rw.seg[i] = src->u.rw.seg[i];
288  break;
289  case BLKIF_OP_DISCARD:
290  dst->u.discard.flag = src->u.discard.flag;
291  dst->u.discard.id = src->u.discard.id;
292  dst->u.discard.sector_number = src->u.discard.sector_number;
293  dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
294  break;
295  default:
296  break;
297  }
298 }
299 
300 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */
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