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tmem.c
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1 /*
2  * Xen implementation for transcendent memory (tmem)
3  *
4  * Copyright (C) 2009-2011 Oracle Corp. All rights reserved.
5  * Author: Dan Magenheimer
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/types.h>
10 #include <linux/init.h>
11 #include <linux/pagemap.h>
12 #include <linux/cleancache.h>
13 
14 /* temporary ifdef until include/linux/frontswap.h is upstream */
15 #ifdef CONFIG_FRONTSWAP
16 #include <linux/frontswap.h>
17 #endif
18 
19 #include <xen/xen.h>
20 #include <xen/interface/xen.h>
21 #include <asm/xen/hypercall.h>
22 #include <asm/xen/page.h>
23 #include <asm/xen/hypervisor.h>
24 #include <xen/tmem.h>
25 
26 #define TMEM_CONTROL 0
27 #define TMEM_NEW_POOL 1
28 #define TMEM_DESTROY_POOL 2
29 #define TMEM_NEW_PAGE 3
30 #define TMEM_PUT_PAGE 4
31 #define TMEM_GET_PAGE 5
32 #define TMEM_FLUSH_PAGE 6
33 #define TMEM_FLUSH_OBJECT 7
34 #define TMEM_READ 8
35 #define TMEM_WRITE 9
36 #define TMEM_XCHG 10
37 
38 /* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */
39 #define TMEM_POOL_PERSIST 1
40 #define TMEM_POOL_SHARED 2
41 #define TMEM_POOL_PAGESIZE_SHIFT 4
42 #define TMEM_VERSION_SHIFT 24
43 
44 
48 };
49 
50 struct tmem_oid {
51  u64 oid[3];
52 };
53 
54 #define TMEM_POOL_PRIVATE_UUID { 0, 0 }
55 
56 /* flags for tmem_ops.new_pool */
57 #define TMEM_POOL_PERSIST 1
58 #define TMEM_POOL_SHARED 2
59 
60 /* xen tmem foundation ops/hypercalls */
61 
62 static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid,
63  u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len)
64 {
65  struct tmem_op op;
66  int rc = 0;
67 
68  op.cmd = tmem_cmd;
69  op.pool_id = tmem_pool;
70  op.u.gen.oid[0] = oid.oid[0];
71  op.u.gen.oid[1] = oid.oid[1];
72  op.u.gen.oid[2] = oid.oid[2];
73  op.u.gen.index = index;
74  op.u.gen.tmem_offset = tmem_offset;
75  op.u.gen.pfn_offset = pfn_offset;
76  op.u.gen.len = len;
77  set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn);
78  rc = HYPERVISOR_tmem_op(&op);
79  return rc;
80 }
81 
82 static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
83  u32 flags, unsigned long pagesize)
84 {
85  struct tmem_op op;
86  int rc = 0, pageshift;
87 
88  for (pageshift = 0; pagesize != 1; pageshift++)
89  pagesize >>= 1;
90  flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT;
92  op.cmd = TMEM_NEW_POOL;
93  op.u.new.uuid[0] = uuid.uuid_lo;
94  op.u.new.uuid[1] = uuid.uuid_hi;
95  op.u.new.flags = flags;
96  rc = HYPERVISOR_tmem_op(&op);
97  return rc;
98 }
99 
100 /* xen generic tmem ops */
101 
102 static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
103  u32 index, unsigned long pfn)
104 {
105  unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
106 
107  return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
108  gmfn, 0, 0, 0);
109 }
110 
111 static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
112  u32 index, unsigned long pfn)
113 {
114  unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
115 
116  return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
117  gmfn, 0, 0, 0);
118 }
119 
120 static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
121 {
122  return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
123  0, 0, 0, 0);
124 }
125 
126 static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
127 {
128  return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
129 }
130 
132 
133 static int __init enable_tmem(char *s)
134 {
135  tmem_enabled = true;
136  return 1;
137 }
138 __setup("tmem", enable_tmem);
139 
140 #ifdef CONFIG_CLEANCACHE
141 static int xen_tmem_destroy_pool(u32 pool_id)
142 {
143  struct tmem_oid oid = { { 0 } };
144 
145  return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
146 }
147 
148 /* cleancache ops */
149 
150 static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
151  pgoff_t index, struct page *page)
152 {
153  u32 ind = (u32) index;
154  struct tmem_oid oid = *(struct tmem_oid *)&key;
155  unsigned long pfn = page_to_pfn(page);
156 
157  if (pool < 0)
158  return;
159  if (ind != index)
160  return;
161  mb(); /* ensure page is quiescent; tmem may address it with an alias */
162  (void)xen_tmem_put_page((u32)pool, oid, ind, pfn);
163 }
164 
165 static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
166  pgoff_t index, struct page *page)
167 {
168  u32 ind = (u32) index;
169  struct tmem_oid oid = *(struct tmem_oid *)&key;
170  unsigned long pfn = page_to_pfn(page);
171  int ret;
172 
173  /* translate return values to linux semantics */
174  if (pool < 0)
175  return -1;
176  if (ind != index)
177  return -1;
178  ret = xen_tmem_get_page((u32)pool, oid, ind, pfn);
179  if (ret == 1)
180  return 0;
181  else
182  return -1;
183 }
184 
185 static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
186  pgoff_t index)
187 {
188  u32 ind = (u32) index;
189  struct tmem_oid oid = *(struct tmem_oid *)&key;
190 
191  if (pool < 0)
192  return;
193  if (ind != index)
194  return;
195  (void)xen_tmem_flush_page((u32)pool, oid, ind);
196 }
197 
198 static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
199 {
200  struct tmem_oid oid = *(struct tmem_oid *)&key;
201 
202  if (pool < 0)
203  return;
204  (void)xen_tmem_flush_object((u32)pool, oid);
205 }
206 
207 static void tmem_cleancache_flush_fs(int pool)
208 {
209  if (pool < 0)
210  return;
211  (void)xen_tmem_destroy_pool((u32)pool);
212 }
213 
214 static int tmem_cleancache_init_fs(size_t pagesize)
215 {
216  struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
217 
218  return xen_tmem_new_pool(uuid_private, 0, pagesize);
219 }
220 
221 static int tmem_cleancache_init_shared_fs(char *uuid, size_t pagesize)
222 {
223  struct tmem_pool_uuid shared_uuid;
224 
225  shared_uuid.uuid_lo = *(u64 *)uuid;
226  shared_uuid.uuid_hi = *(u64 *)(&uuid[8]);
227  return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
228 }
229 
230 static bool __initdata use_cleancache = true;
231 
232 static int __init no_cleancache(char *s)
233 {
234  use_cleancache = false;
235  return 1;
236 }
237 __setup("nocleancache", no_cleancache);
238 
239 static struct cleancache_ops __initdata tmem_cleancache_ops = {
240  .put_page = tmem_cleancache_put_page,
241  .get_page = tmem_cleancache_get_page,
242  .invalidate_page = tmem_cleancache_flush_page,
243  .invalidate_inode = tmem_cleancache_flush_inode,
244  .invalidate_fs = tmem_cleancache_flush_fs,
245  .init_shared_fs = tmem_cleancache_init_shared_fs,
246  .init_fs = tmem_cleancache_init_fs
247 };
248 #endif
249 
250 #ifdef CONFIG_FRONTSWAP
251 /* frontswap tmem operations */
252 
253 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
254 static int tmem_frontswap_poolid;
255 
256 /*
257  * Swizzling increases objects per swaptype, increasing tmem concurrency
258  * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
259  */
260 #define SWIZ_BITS 4
261 #define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
262 #define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
263 #define iswiz(_ind) (_ind >> SWIZ_BITS)
264 
265 static inline struct tmem_oid oswiz(unsigned type, u32 ind)
266 {
267  struct tmem_oid oid = { .oid = { 0 } };
268  oid.oid[0] = _oswiz(type, ind);
269  return oid;
270 }
271 
272 /* returns 0 if the page was successfully put into frontswap, -1 if not */
273 static int tmem_frontswap_store(unsigned type, pgoff_t offset,
274  struct page *page)
275 {
276  u64 ind64 = (u64)offset;
277  u32 ind = (u32)offset;
278  unsigned long pfn = page_to_pfn(page);
279  int pool = tmem_frontswap_poolid;
280  int ret;
281 
282  if (pool < 0)
283  return -1;
284  if (ind64 != ind)
285  return -1;
286  mb(); /* ensure page is quiescent; tmem may address it with an alias */
287  ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);
288  /* translate Xen tmem return values to linux semantics */
289  if (ret == 1)
290  return 0;
291  else
292  return -1;
293 }
294 
295 /*
296  * returns 0 if the page was successfully gotten from frontswap, -1 if
297  * was not present (should never happen!)
298  */
299 static int tmem_frontswap_load(unsigned type, pgoff_t offset,
300  struct page *page)
301 {
302  u64 ind64 = (u64)offset;
303  u32 ind = (u32)offset;
304  unsigned long pfn = page_to_pfn(page);
305  int pool = tmem_frontswap_poolid;
306  int ret;
307 
308  if (pool < 0)
309  return -1;
310  if (ind64 != ind)
311  return -1;
312  ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);
313  /* translate Xen tmem return values to linux semantics */
314  if (ret == 1)
315  return 0;
316  else
317  return -1;
318 }
319 
320 /* flush a single page from frontswap */
321 static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
322 {
323  u64 ind64 = (u64)offset;
324  u32 ind = (u32)offset;
325  int pool = tmem_frontswap_poolid;
326 
327  if (pool < 0)
328  return;
329  if (ind64 != ind)
330  return;
331  (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
332 }
333 
334 /* flush all pages from the passed swaptype */
335 static void tmem_frontswap_flush_area(unsigned type)
336 {
337  int pool = tmem_frontswap_poolid;
338  int ind;
339 
340  if (pool < 0)
341  return;
342  for (ind = SWIZ_MASK; ind >= 0; ind--)
343  (void)xen_tmem_flush_object(pool, oswiz(type, ind));
344 }
345 
346 static void tmem_frontswap_init(unsigned ignored)
347 {
348  struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
349 
350  /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
351  if (tmem_frontswap_poolid < 0)
352  tmem_frontswap_poolid =
353  xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
354 }
355 
356 static bool __initdata use_frontswap = true;
357 
358 static int __init no_frontswap(char *s)
359 {
360  use_frontswap = false;
361  return 1;
362 }
363 __setup("nofrontswap", no_frontswap);
364 
365 static struct frontswap_ops __initdata tmem_frontswap_ops = {
366  .store = tmem_frontswap_store,
367  .load = tmem_frontswap_load,
368  .invalidate_page = tmem_frontswap_flush_page,
369  .invalidate_area = tmem_frontswap_flush_area,
370  .init = tmem_frontswap_init
371 };
372 #endif
373 
374 static int __init xen_tmem_init(void)
375 {
376  if (!xen_domain())
377  return 0;
378 #ifdef CONFIG_FRONTSWAP
379  if (tmem_enabled && use_frontswap) {
380  char *s = "";
381  struct frontswap_ops old_ops =
382  frontswap_register_ops(&tmem_frontswap_ops);
383 
384  tmem_frontswap_poolid = -1;
385  if (old_ops.init != NULL)
386  s = " (WARNING: frontswap_ops overridden)";
387  printk(KERN_INFO "frontswap enabled, RAM provided by "
388  "Xen Transcendent Memory\n");
389  }
390 #endif
391 #ifdef CONFIG_CLEANCACHE
392  BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
393  if (tmem_enabled && use_cleancache) {
394  char *s = "";
395  struct cleancache_ops old_ops =
396  cleancache_register_ops(&tmem_cleancache_ops);
397  if (old_ops.init_fs != NULL)
398  s = " (WARNING: cleancache_ops overridden)";
399  printk(KERN_INFO "cleancache enabled, RAM provided by "
400  "Xen Transcendent Memory%s\n", s);
401  }
402 #endif
403  return 0;
404 }
405 
406 module_init(xen_tmem_init)