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 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
9
10 #include <linux/module.h>
11 #include <linux/kernel.h>
12 #include <linux/types.h>
13 #include <linux/init.h>
14 #include <linux/pagemap.h>
15 #include <linux/cleancache.h>
16 #include <linux/frontswap.h>
17
18 #include <xen/xen.h>
19 #include <xen/interface/xen.h>
20 #include <xen/page.h>
21 #include <asm/xen/hypercall.h>
22 #include <asm/xen/hypervisor.h>
23 #include <xen/tmem.h>
24
25 #ifndef CONFIG_XEN_TMEM_MODULE
26 bool __read_mostly tmem_enabled = false;
27
enable_tmem(char * s)28 static int __init enable_tmem(char *s)
29 {
30 tmem_enabled = true;
31 return 1;
32 }
33 __setup("tmem", enable_tmem);
34 #endif
35
36 #ifdef CONFIG_CLEANCACHE
37 static bool cleancache __read_mostly = true;
38 module_param(cleancache, bool, S_IRUGO);
39 static bool selfballooning __read_mostly = true;
40 module_param(selfballooning, bool, S_IRUGO);
41 #endif /* CONFIG_CLEANCACHE */
42
43 #ifdef CONFIG_FRONTSWAP
44 static bool frontswap __read_mostly = true;
45 module_param(frontswap, bool, S_IRUGO);
46 #else /* CONFIG_FRONTSWAP */
47 #define frontswap (0)
48 #endif /* CONFIG_FRONTSWAP */
49
50 #ifdef CONFIG_XEN_SELFBALLOONING
51 static bool selfshrinking __read_mostly = true;
52 module_param(selfshrinking, bool, S_IRUGO);
53 #endif /* CONFIG_XEN_SELFBALLOONING */
54
55 #define TMEM_CONTROL 0
56 #define TMEM_NEW_POOL 1
57 #define TMEM_DESTROY_POOL 2
58 #define TMEM_NEW_PAGE 3
59 #define TMEM_PUT_PAGE 4
60 #define TMEM_GET_PAGE 5
61 #define TMEM_FLUSH_PAGE 6
62 #define TMEM_FLUSH_OBJECT 7
63 #define TMEM_READ 8
64 #define TMEM_WRITE 9
65 #define TMEM_XCHG 10
66
67 /* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */
68 #define TMEM_POOL_PERSIST 1
69 #define TMEM_POOL_SHARED 2
70 #define TMEM_POOL_PAGESIZE_SHIFT 4
71 #define TMEM_VERSION_SHIFT 24
72
73
74 struct tmem_pool_uuid {
75 u64 uuid_lo;
76 u64 uuid_hi;
77 };
78
79 struct tmem_oid {
80 u64 oid[3];
81 };
82
83 #define TMEM_POOL_PRIVATE_UUID { 0, 0 }
84
85 /* flags for tmem_ops.new_pool */
86 #define TMEM_POOL_PERSIST 1
87 #define TMEM_POOL_SHARED 2
88
89 /* xen tmem foundation ops/hypercalls */
90
xen_tmem_op(u32 tmem_cmd,u32 tmem_pool,struct tmem_oid oid,u32 index,unsigned long gmfn,u32 tmem_offset,u32 pfn_offset,u32 len)91 static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid,
92 u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len)
93 {
94 struct tmem_op op;
95 int rc = 0;
96
97 op.cmd = tmem_cmd;
98 op.pool_id = tmem_pool;
99 op.u.gen.oid[0] = oid.oid[0];
100 op.u.gen.oid[1] = oid.oid[1];
101 op.u.gen.oid[2] = oid.oid[2];
102 op.u.gen.index = index;
103 op.u.gen.tmem_offset = tmem_offset;
104 op.u.gen.pfn_offset = pfn_offset;
105 op.u.gen.len = len;
106 set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn);
107 rc = HYPERVISOR_tmem_op(&op);
108 return rc;
109 }
110
xen_tmem_new_pool(struct tmem_pool_uuid uuid,u32 flags,unsigned long pagesize)111 static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
112 u32 flags, unsigned long pagesize)
113 {
114 struct tmem_op op;
115 int rc = 0, pageshift;
116
117 for (pageshift = 0; pagesize != 1; pageshift++)
118 pagesize >>= 1;
119 flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT;
120 flags |= TMEM_SPEC_VERSION << TMEM_VERSION_SHIFT;
121 op.cmd = TMEM_NEW_POOL;
122 op.u.new.uuid[0] = uuid.uuid_lo;
123 op.u.new.uuid[1] = uuid.uuid_hi;
124 op.u.new.flags = flags;
125 rc = HYPERVISOR_tmem_op(&op);
126 return rc;
127 }
128
129 /* xen generic tmem ops */
130
xen_tmem_put_page(u32 pool_id,struct tmem_oid oid,u32 index,struct page * page)131 static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
132 u32 index, struct page *page)
133 {
134 return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
135 xen_page_to_gfn(page), 0, 0, 0);
136 }
137
xen_tmem_get_page(u32 pool_id,struct tmem_oid oid,u32 index,struct page * page)138 static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
139 u32 index, struct page *page)
140 {
141 return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
142 xen_page_to_gfn(page), 0, 0, 0);
143 }
144
xen_tmem_flush_page(u32 pool_id,struct tmem_oid oid,u32 index)145 static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
146 {
147 return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
148 0, 0, 0, 0);
149 }
150
xen_tmem_flush_object(u32 pool_id,struct tmem_oid oid)151 static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
152 {
153 return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
154 }
155
156
157 #ifdef CONFIG_CLEANCACHE
xen_tmem_destroy_pool(u32 pool_id)158 static int xen_tmem_destroy_pool(u32 pool_id)
159 {
160 struct tmem_oid oid = { { 0 } };
161
162 return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
163 }
164
165 /* cleancache ops */
166
tmem_cleancache_put_page(int pool,struct cleancache_filekey key,pgoff_t index,struct page * page)167 static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
168 pgoff_t index, struct page *page)
169 {
170 u32 ind = (u32) index;
171 struct tmem_oid oid = *(struct tmem_oid *)&key;
172
173 if (pool < 0)
174 return;
175 if (ind != index)
176 return;
177 mb(); /* ensure page is quiescent; tmem may address it with an alias */
178 (void)xen_tmem_put_page((u32)pool, oid, ind, page);
179 }
180
tmem_cleancache_get_page(int pool,struct cleancache_filekey key,pgoff_t index,struct page * page)181 static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
182 pgoff_t index, struct page *page)
183 {
184 u32 ind = (u32) index;
185 struct tmem_oid oid = *(struct tmem_oid *)&key;
186 int ret;
187
188 /* translate return values to linux semantics */
189 if (pool < 0)
190 return -1;
191 if (ind != index)
192 return -1;
193 ret = xen_tmem_get_page((u32)pool, oid, ind, page);
194 if (ret == 1)
195 return 0;
196 else
197 return -1;
198 }
199
tmem_cleancache_flush_page(int pool,struct cleancache_filekey key,pgoff_t index)200 static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
201 pgoff_t index)
202 {
203 u32 ind = (u32) index;
204 struct tmem_oid oid = *(struct tmem_oid *)&key;
205
206 if (pool < 0)
207 return;
208 if (ind != index)
209 return;
210 (void)xen_tmem_flush_page((u32)pool, oid, ind);
211 }
212
tmem_cleancache_flush_inode(int pool,struct cleancache_filekey key)213 static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
214 {
215 struct tmem_oid oid = *(struct tmem_oid *)&key;
216
217 if (pool < 0)
218 return;
219 (void)xen_tmem_flush_object((u32)pool, oid);
220 }
221
tmem_cleancache_flush_fs(int pool)222 static void tmem_cleancache_flush_fs(int pool)
223 {
224 if (pool < 0)
225 return;
226 (void)xen_tmem_destroy_pool((u32)pool);
227 }
228
tmem_cleancache_init_fs(size_t pagesize)229 static int tmem_cleancache_init_fs(size_t pagesize)
230 {
231 struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
232
233 return xen_tmem_new_pool(uuid_private, 0, pagesize);
234 }
235
tmem_cleancache_init_shared_fs(uuid_t * uuid,size_t pagesize)236 static int tmem_cleancache_init_shared_fs(uuid_t *uuid, size_t pagesize)
237 {
238 struct tmem_pool_uuid shared_uuid;
239
240 shared_uuid.uuid_lo = *(u64 *)&uuid->b[0];
241 shared_uuid.uuid_hi = *(u64 *)&uuid->b[8];
242 return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
243 }
244
245 static const struct cleancache_ops tmem_cleancache_ops = {
246 .put_page = tmem_cleancache_put_page,
247 .get_page = tmem_cleancache_get_page,
248 .invalidate_page = tmem_cleancache_flush_page,
249 .invalidate_inode = tmem_cleancache_flush_inode,
250 .invalidate_fs = tmem_cleancache_flush_fs,
251 .init_shared_fs = tmem_cleancache_init_shared_fs,
252 .init_fs = tmem_cleancache_init_fs
253 };
254 #endif
255
256 #ifdef CONFIG_FRONTSWAP
257 /* frontswap tmem operations */
258
259 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
260 static int tmem_frontswap_poolid;
261
262 /*
263 * Swizzling increases objects per swaptype, increasing tmem concurrency
264 * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
265 */
266 #define SWIZ_BITS 4
267 #define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
268 #define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
269 #define iswiz(_ind) (_ind >> SWIZ_BITS)
270
oswiz(unsigned type,u32 ind)271 static inline struct tmem_oid oswiz(unsigned type, u32 ind)
272 {
273 struct tmem_oid oid = { .oid = { 0 } };
274 oid.oid[0] = _oswiz(type, ind);
275 return oid;
276 }
277
278 /* returns 0 if the page was successfully put into frontswap, -1 if not */
tmem_frontswap_store(unsigned type,pgoff_t offset,struct page * page)279 static int tmem_frontswap_store(unsigned type, pgoff_t offset,
280 struct page *page)
281 {
282 u64 ind64 = (u64)offset;
283 u32 ind = (u32)offset;
284 int pool = tmem_frontswap_poolid;
285 int ret;
286
287 /* THP isn't supported */
288 if (PageTransHuge(page))
289 return -1;
290
291 if (pool < 0)
292 return -1;
293 if (ind64 != ind)
294 return -1;
295 mb(); /* ensure page is quiescent; tmem may address it with an alias */
296 ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), page);
297 /* translate Xen tmem return values to linux semantics */
298 if (ret == 1)
299 return 0;
300 else
301 return -1;
302 }
303
304 /*
305 * returns 0 if the page was successfully gotten from frontswap, -1 if
306 * was not present (should never happen!)
307 */
tmem_frontswap_load(unsigned type,pgoff_t offset,struct page * page)308 static int tmem_frontswap_load(unsigned type, pgoff_t offset,
309 struct page *page)
310 {
311 u64 ind64 = (u64)offset;
312 u32 ind = (u32)offset;
313 int pool = tmem_frontswap_poolid;
314 int ret;
315
316 if (pool < 0)
317 return -1;
318 if (ind64 != ind)
319 return -1;
320 ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), page);
321 /* translate Xen tmem return values to linux semantics */
322 if (ret == 1)
323 return 0;
324 else
325 return -1;
326 }
327
328 /* flush a single page from frontswap */
tmem_frontswap_flush_page(unsigned type,pgoff_t offset)329 static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
330 {
331 u64 ind64 = (u64)offset;
332 u32 ind = (u32)offset;
333 int pool = tmem_frontswap_poolid;
334
335 if (pool < 0)
336 return;
337 if (ind64 != ind)
338 return;
339 (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
340 }
341
342 /* flush all pages from the passed swaptype */
tmem_frontswap_flush_area(unsigned type)343 static void tmem_frontswap_flush_area(unsigned type)
344 {
345 int pool = tmem_frontswap_poolid;
346 int ind;
347
348 if (pool < 0)
349 return;
350 for (ind = SWIZ_MASK; ind >= 0; ind--)
351 (void)xen_tmem_flush_object(pool, oswiz(type, ind));
352 }
353
tmem_frontswap_init(unsigned ignored)354 static void tmem_frontswap_init(unsigned ignored)
355 {
356 struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
357
358 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
359 if (tmem_frontswap_poolid < 0)
360 tmem_frontswap_poolid =
361 xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
362 }
363
364 static struct frontswap_ops tmem_frontswap_ops = {
365 .store = tmem_frontswap_store,
366 .load = tmem_frontswap_load,
367 .invalidate_page = tmem_frontswap_flush_page,
368 .invalidate_area = tmem_frontswap_flush_area,
369 .init = tmem_frontswap_init
370 };
371 #endif
372
xen_tmem_init(void)373 static int __init xen_tmem_init(void)
374 {
375 if (!xen_domain())
376 return 0;
377 #ifdef CONFIG_FRONTSWAP
378 if (tmem_enabled && frontswap) {
379 char *s = "";
380
381 tmem_frontswap_poolid = -1;
382 frontswap_register_ops(&tmem_frontswap_ops);
383 pr_info("frontswap enabled, RAM provided by Xen Transcendent Memory%s\n",
384 s);
385 }
386 #endif
387 #ifdef CONFIG_CLEANCACHE
388 BUILD_BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
389 if (tmem_enabled && cleancache) {
390 int err;
391
392 err = cleancache_register_ops(&tmem_cleancache_ops);
393 if (err)
394 pr_warn("xen-tmem: failed to enable cleancache: %d\n",
395 err);
396 else
397 pr_info("cleancache enabled, RAM provided by "
398 "Xen Transcendent Memory\n");
399 }
400 #endif
401 #ifdef CONFIG_XEN_SELFBALLOONING
402 /*
403 * There is no point of driving pages to the swap system if they
404 * aren't going anywhere in tmem universe.
405 */
406 if (!frontswap) {
407 selfshrinking = false;
408 selfballooning = false;
409 }
410 xen_selfballoon_init(selfballooning, selfshrinking);
411 #endif
412 return 0;
413 }
414
415 module_init(xen_tmem_init)
416 MODULE_LICENSE("GPL");
417 MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
418 MODULE_DESCRIPTION("Shim to Xen transcendent memory");
419