xen-vtx-unstable

annotate linux-2.6-xen-sparse/arch/xen/kernel/gnttab.c @ 6349:5b1ed5b39451

Cleanup grant table code.
- keep count of free references
- let callbacks specify the number of references they need at least
- get rid of terminal reference
- simplify and more correct locking for callbacks
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
author cl349@firebug.cl.cam.ac.uk
date Tue Aug 23 13:11:31 2005 +0000 (2005-08-23)
parents 4956ea5b1e34
children d760699356fd
rev   line source
cl349@4693 1 /******************************************************************************
cl349@4693 2 * gnttab.c
cl349@4693 3 *
cl349@4693 4 * Two sets of functionality:
cl349@4693 5 * 1. Granting foreign access to our memory reservation.
cl349@4693 6 * 2. Accessing others' memory reservations via grant references.
cl349@4693 7 * (i.e., mechanisms for both sender and recipient of grant references)
cl349@4693 8 *
cl349@4693 9 * Copyright (c) 2005, Christopher Clark
cl349@4693 10 * Copyright (c) 2004, K A Fraser
cl349@4693 11 */
cl349@4693 12
cl349@4693 13 #include <linux/config.h>
cl349@4693 14 #include <linux/module.h>
cl349@4693 15 #include <linux/sched.h>
cl349@4693 16 #include <asm/pgtable.h>
cl349@4693 17 #include <asm/fixmap.h>
cl349@4693 18 #include <asm/uaccess.h>
cl349@4693 19 #include <asm-xen/xen_proc.h>
cl349@4693 20 #include <asm-xen/linux-public/privcmd.h>
cl349@4693 21 #include <asm-xen/gnttab.h>
kaf24@5402 22 #include <asm-xen/synch_bitops.h>
cl349@4693 23
cl349@4693 24 #if 1
cl349@4693 25 #define ASSERT(_p) \
cl349@4693 26 if ( !(_p) ) { printk(KERN_ALERT"Assertion '%s': line %d, file %s\n", \
cl349@4693 27 #_p , __LINE__, __FILE__); *(int*)0=0; }
cl349@4693 28 #else
cl349@4693 29 #define ASSERT(_p) ((void)0)
cl349@4693 30 #endif
cl349@4693 31
cl349@4693 32 #define WPRINTK(fmt, args...) \
cl349@4693 33 printk(KERN_WARNING "xen_grant: " fmt, ##args)
cl349@4693 34
cl349@4693 35
cl349@4693 36 EXPORT_SYMBOL(gnttab_grant_foreign_access);
cl349@4693 37 EXPORT_SYMBOL(gnttab_end_foreign_access);
cl349@4693 38 EXPORT_SYMBOL(gnttab_query_foreign_access);
cl349@4693 39 EXPORT_SYMBOL(gnttab_grant_foreign_transfer);
cl349@4693 40 EXPORT_SYMBOL(gnttab_end_foreign_transfer);
cl349@4693 41 EXPORT_SYMBOL(gnttab_alloc_grant_references);
cl349@4693 42 EXPORT_SYMBOL(gnttab_free_grant_references);
cl349@6347 43 EXPORT_SYMBOL(gnttab_free_grant_reference);
cl349@4693 44 EXPORT_SYMBOL(gnttab_claim_grant_reference);
cl349@4693 45 EXPORT_SYMBOL(gnttab_release_grant_reference);
cl349@4693 46 EXPORT_SYMBOL(gnttab_grant_foreign_access_ref);
cl349@4693 47 EXPORT_SYMBOL(gnttab_grant_foreign_transfer_ref);
cl349@4693 48
cl349@6349 49 #define NR_GRANT_ENTRIES (NR_GRANT_FRAMES * PAGE_SIZE / sizeof(grant_entry_t))
cl349@6349 50 #define GNTTAB_LIST_END (NR_GRANT_ENTRIES + 1)
cl349@6349 51
cl349@6349 52 static grant_ref_t gnttab_list[NR_GRANT_ENTRIES];
cl349@6349 53 static int gnttab_free_count = NR_GRANT_ENTRIES;
cl349@4693 54 static grant_ref_t gnttab_free_head;
cl349@6349 55 static spinlock_t gnttab_list_lock = SPIN_LOCK_UNLOCKED;
cl349@4693 56
cl349@4693 57 static grant_entry_t *shared;
cl349@4693 58
cl349@6339 59 static struct gnttab_free_callback *gnttab_free_callback_list = NULL;
cl349@6339 60
cl349@6349 61 static int
cl349@6349 62 get_free_entries(int count)
cl349@4693 63 {
cl349@6349 64 unsigned long flags;
cl349@6349 65 int ref;
cl349@6349 66 grant_ref_t head;
cl349@6349 67 spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6349 68 if (gnttab_free_count < count) {
cl349@6349 69 spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@6349 70 return -1;
cl349@6349 71 }
cl349@6349 72 ref = head = gnttab_free_head;
cl349@6349 73 gnttab_free_count -= count;
cl349@6349 74 while (count-- > 1)
cl349@6349 75 head = gnttab_list[head];
cl349@6349 76 gnttab_free_head = gnttab_list[head];
cl349@6349 77 gnttab_list[head] = GNTTAB_LIST_END;
cl349@6349 78 spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@6349 79 return ref;
cl349@4693 80 }
cl349@4693 81
cl349@6349 82 #define get_free_entry() get_free_entries(1)
cl349@6349 83
cl349@6349 84 static void
cl349@6349 85 do_free_callbacks(void)
cl349@6339 86 {
cl349@6346 87 struct gnttab_free_callback *callback = gnttab_free_callback_list, *next;
cl349@6339 88 gnttab_free_callback_list = NULL;
cl349@6339 89 while (callback) {
cl349@6342 90 next = callback->next;
cl349@6349 91 if (gnttab_free_count >= callback->count) {
cl349@6349 92 callback->next = NULL;
cl349@6349 93 callback->fn(callback->arg);
cl349@6349 94 } else {
cl349@6349 95 callback->next = gnttab_free_callback_list;
cl349@6349 96 gnttab_free_callback_list = callback;
cl349@6349 97 }
cl349@6342 98 callback = next;
cl349@6339 99 }
cl349@6339 100 }
cl349@6339 101
cl349@4693 102 static inline void
cl349@6349 103 check_free_callbacks(void)
cl349@4693 104 {
cl349@6349 105 if (unlikely(gnttab_free_callback_list))
cl349@6349 106 do_free_callbacks();
cl349@6349 107 }
cl349@6349 108
cl349@6349 109 static void
cl349@6349 110 put_free_entry(grant_ref_t ref)
cl349@6349 111 {
cl349@6346 112 unsigned long flags;
cl349@6349 113 spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6349 114 gnttab_list[ref] = gnttab_free_head;
cl349@6349 115 gnttab_free_head = ref;
cl349@6349 116 gnttab_free_count++;
cl349@6349 117 check_free_callbacks();
cl349@6349 118 spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@4693 119 }
cl349@4693 120
cl349@4693 121 /*
cl349@4693 122 * Public grant-issuing interface functions
cl349@4693 123 */
cl349@4693 124
cl349@4693 125 int
cl349@6349 126 gnttab_grant_foreign_access(domid_t domid, unsigned long frame, int readonly)
cl349@4693 127 {
cl349@4693 128 int ref;
cl349@4693 129
cl349@4693 130 if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693 131 return -ENOSPC;
cl349@4693 132
cl349@4693 133 shared[ref].frame = frame;
cl349@4693 134 shared[ref].domid = domid;
cl349@4693 135 wmb();
cl349@4693 136 shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693 137
cl349@4693 138 return ref;
cl349@4693 139 }
cl349@4693 140
cl349@4693 141 void
cl349@6349 142 gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
cl349@6349 143 unsigned long frame, int readonly)
cl349@4693 144 {
cl349@4693 145 shared[ref].frame = frame;
cl349@4693 146 shared[ref].domid = domid;
cl349@4693 147 wmb();
cl349@4693 148 shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693 149 }
cl349@4693 150
cl349@4693 151
cl349@4693 152 int
cl349@6349 153 gnttab_query_foreign_access(grant_ref_t ref)
cl349@4693 154 {
cl349@4693 155 u16 nflags;
cl349@4693 156
cl349@4693 157 nflags = shared[ref].flags;
cl349@4693 158
cl349@4693 159 return ( nflags & (GTF_reading|GTF_writing) );
cl349@4693 160 }
cl349@4693 161
cl349@4693 162 void
cl349@6349 163 gnttab_end_foreign_access(grant_ref_t ref, int readonly)
cl349@4693 164 {
cl349@4693 165 u16 flags, nflags;
cl349@4693 166
cl349@4693 167 nflags = shared[ref].flags;
cl349@4693 168 do {
cl349@4693 169 if ( (flags = nflags) & (GTF_reading|GTF_writing) )
cl349@4693 170 printk(KERN_ALERT "WARNING: g.e. still in use!\n");
cl349@4693 171 }
sos22@5391 172 while ( (nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) != flags );
cl349@4693 173
cl349@4693 174 put_free_entry(ref);
cl349@4693 175 }
cl349@4693 176
cl349@4693 177 int
cl349@6349 178 gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
cl349@4693 179 {
cl349@4693 180 int ref;
cl349@4693 181
cl349@4693 182 if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693 183 return -ENOSPC;
cl349@4693 184
cl349@4693 185 shared[ref].frame = pfn;
cl349@4693 186 shared[ref].domid = domid;
cl349@4693 187 wmb();
cl349@4693 188 shared[ref].flags = GTF_accept_transfer;
cl349@4693 189
cl349@4693 190 return ref;
cl349@4693 191 }
cl349@4693 192
cl349@4693 193 void
cl349@6349 194 gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
cl349@6349 195 unsigned long pfn)
cl349@4693 196 {
cl349@4693 197 shared[ref].frame = pfn;
cl349@4693 198 shared[ref].domid = domid;
cl349@4693 199 wmb();
cl349@4693 200 shared[ref].flags = GTF_accept_transfer;
cl349@4693 201 }
cl349@4693 202
cl349@4693 203 unsigned long
cl349@6349 204 gnttab_end_foreign_transfer(grant_ref_t ref)
cl349@4693 205 {
cl349@4693 206 unsigned long frame = 0;
cl349@4693 207 u16 flags;
cl349@4693 208
cl349@4693 209 flags = shared[ref].flags;
vh249@5828 210 #ifdef CONFIG_XEN_NETDEV_GRANT_RX
vh249@5828 211 /*
vh249@5828 212 * But can't flags == (GTF_accept_transfer | GTF_transfer_completed)
vh249@5828 213 * if gnttab_donate executes without interruption???
vh249@5828 214 */
vh249@5828 215 #else
cl349@4693 216 ASSERT(flags == (GTF_accept_transfer | GTF_transfer_committed));
vh249@5828 217 #endif
cl349@4693 218 /*
cl349@4693 219 * If a transfer is committed then wait for the frame address to appear.
cl349@4693 220 * Otherwise invalidate the grant entry against future use.
cl349@4693 221 */
cl349@4693 222 if ( likely(flags != GTF_accept_transfer) ||
sos22@5391 223 (synch_cmpxchg(&shared[ref].flags, flags, 0) != GTF_accept_transfer) )
cl349@4693 224 while ( unlikely((frame = shared[ref].frame) == 0) )
cl349@4693 225 cpu_relax();
cl349@4693 226
cl349@4693 227 put_free_entry(ref);
cl349@4693 228
cl349@4693 229 return frame;
cl349@4693 230 }
cl349@4693 231
cl349@4693 232 void
cl349@6349 233 gnttab_free_grant_reference(grant_ref_t ref)
cl349@6339 234 {
cl349@6339 235
cl349@6339 236 put_free_entry(ref);
cl349@6339 237 }
cl349@6339 238
cl349@6339 239 void
cl349@6349 240 gnttab_free_grant_references(grant_ref_t head)
cl349@4693 241 {
cl349@6339 242 grant_ref_t ref;
cl349@6349 243 unsigned long flags;
cl349@6349 244 int count = 1;
cl349@6349 245 if (head == GNTTAB_LIST_END)
cl349@6349 246 return;
cl349@6349 247 spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6349 248 ref = head;
cl349@6349 249 while (gnttab_list[ref] != GNTTAB_LIST_END) {
cl349@6349 250 ref = gnttab_list[ref];
cl349@6349 251 count++;
vh249@5272 252 }
cl349@6349 253 gnttab_list[ref] = gnttab_free_head;
cl349@6349 254 gnttab_free_head = head;
cl349@6349 255 gnttab_free_count += count;
cl349@6349 256 check_free_callbacks();
cl349@6349 257 spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@4693 258 }
cl349@4693 259
cl349@4693 260 int
cl349@6349 261 gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
cl349@4693 262 {
cl349@6349 263 int h = get_free_entries(count);
cl349@4693 264
cl349@6349 265 if (h == -1)
cl349@6349 266 return -ENOSPC;
cl349@4693 267
cl349@4693 268 *head = h;
cl349@4693 269
cl349@4693 270 return 0;
cl349@4693 271 }
cl349@4693 272
cl349@4693 273 int
cl349@6349 274 gnttab_claim_grant_reference(grant_ref_t *private_head)
cl349@4693 275 {
cl349@6349 276 grant_ref_t g = *private_head;
cl349@6349 277 if (unlikely(g == GNTTAB_LIST_END))
cl349@4693 278 return -ENOSPC;
cl349@6349 279 *private_head = gnttab_list[g];
cl349@4693 280 return g;
cl349@4693 281 }
cl349@4693 282
cl349@4693 283 void
cl349@6349 284 gnttab_release_grant_reference(grant_ref_t *private_head, grant_ref_t release)
cl349@4693 285 {
cl349@6349 286 gnttab_list[release] = *private_head;
cl349@4693 287 *private_head = release;
cl349@4693 288 }
cl349@4693 289
cl349@6339 290 void
cl349@6339 291 gnttab_request_free_callback(struct gnttab_free_callback *callback,
cl349@6349 292 void (*fn)(void *), void *arg, u16 count)
cl349@6339 293 {
cl349@6346 294 unsigned long flags;
cl349@6349 295 spin_lock_irqsave(&gnttab_list_lock, flags);
cl349@6342 296 if (callback->next)
cl349@6349 297 goto out;
cl349@6342 298 callback->fn = fn;
cl349@6342 299 callback->arg = arg;
cl349@6349 300 callback->count = count;
cl349@6339 301 callback->next = gnttab_free_callback_list;
cl349@6339 302 gnttab_free_callback_list = callback;
cl349@6349 303 check_free_callbacks();
cl349@6349 304 out:
cl349@6349 305 spin_unlock_irqrestore(&gnttab_list_lock, flags);
cl349@6339 306 }
cl349@6339 307
cl349@4693 308 /*
cl349@4693 309 * ProcFS operations
cl349@4693 310 */
cl349@4693 311
cl349@4693 312 #ifdef CONFIG_PROC_FS
cl349@4693 313
cl349@4693 314 static struct proc_dir_entry *grant_pde;
cl349@4693 315
cl349@6349 316 static int
cl349@6349 317 grant_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
cl349@6349 318 unsigned long data)
cl349@4693 319 {
cl349@4693 320 int ret;
cl349@4693 321 privcmd_hypercall_t hypercall;
cl349@4693 322
cl349@4693 323 /* XXX Need safety checks here if using for anything other
cl349@4693 324 * than debugging */
cl349@4693 325 return -ENOSYS;
cl349@4693 326
cl349@4693 327 if ( cmd != IOCTL_PRIVCMD_HYPERCALL )
cl349@4693 328 return -ENOSYS;
cl349@4693 329
cl349@4693 330 if ( copy_from_user(&hypercall, (void *)data, sizeof(hypercall)) )
cl349@4693 331 return -EFAULT;
cl349@4693 332
cl349@4693 333 if ( hypercall.op != __HYPERVISOR_grant_table_op )
cl349@4693 334 return -ENOSYS;
cl349@4693 335
cl349@4693 336 /* hypercall-invoking asm taken from privcmd.c */
cl349@4693 337 __asm__ __volatile__ (
cl349@4693 338 "pushl %%ebx; pushl %%ecx; pushl %%edx; pushl %%esi; pushl %%edi; "
cl349@4693 339 "movl 4(%%eax),%%ebx ;"
cl349@4693 340 "movl 8(%%eax),%%ecx ;"
cl349@4693 341 "movl 12(%%eax),%%edx ;"
cl349@4693 342 "movl 16(%%eax),%%esi ;"
cl349@4693 343 "movl 20(%%eax),%%edi ;"
cl349@4693 344 "movl (%%eax),%%eax ;"
cl349@4693 345 TRAP_INSTR "; "
cl349@4693 346 "popl %%edi; popl %%esi; popl %%edx; popl %%ecx; popl %%ebx"
cl349@4693 347 : "=a" (ret) : "0" (&hypercall) : "memory" );
cl349@4693 348
cl349@4693 349 return ret;
cl349@4693 350 }
cl349@4693 351
cl349@4693 352 static struct file_operations grant_file_ops = {
cl349@4693 353 ioctl: grant_ioctl,
cl349@4693 354 };
cl349@4693 355
cl349@6349 356 static int
cl349@6349 357 grant_read(char *page, char **start, off_t off, int count, int *eof,
cl349@6349 358 void *data)
cl349@4693 359 {
cl349@4693 360 int len;
cl349@4693 361 unsigned int i;
cl349@4693 362 grant_entry_t *gt;
cl349@4693 363
cl349@4693 364 gt = (grant_entry_t *)shared;
cl349@4693 365 len = 0;
cl349@4693 366
cl349@4693 367 for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@4693 368 /* TODO: safety catch here until this can handle >PAGE_SIZE output */
cl349@4693 369 if (len > (PAGE_SIZE - 200))
cl349@4693 370 {
cl349@4693 371 len += sprintf( page + len, "Truncated.\n");
cl349@4693 372 break;
cl349@4693 373 }
cl349@4693 374
cl349@4693 375 if ( gt[i].flags )
cl349@4693 376 len += sprintf( page + len,
cl349@4693 377 "Grant: ref (0x%x) flags (0x%hx) dom (0x%hx) frame (0x%x)\n",
cl349@4693 378 i,
cl349@4693 379 gt[i].flags,
cl349@4693 380 gt[i].domid,
cl349@4693 381 gt[i].frame );
cl349@4693 382
cl349@4693 383 *eof = 1;
cl349@4693 384 return len;
cl349@4693 385 }
cl349@4693 386
cl349@6349 387 static int
cl349@6349 388 grant_write(struct file *file, const char __user *buffer, unsigned long count,
cl349@6349 389 void *data)
cl349@4693 390 {
cl349@4693 391 /* TODO: implement this */
cl349@4693 392 return -ENOSYS;
cl349@4693 393 }
cl349@4693 394
cl349@4693 395 #endif /* CONFIG_PROC_FS */
cl349@4693 396
cl349@6349 397 int
cl349@6349 398 gnttab_resume(void)
cl349@4693 399 {
cl349@4693 400 gnttab_setup_table_t setup;
cl349@4693 401 unsigned long frames[NR_GRANT_FRAMES];
cl349@4693 402 int i;
cl349@4693 403
cl349@4693 404 setup.dom = DOMID_SELF;
cl349@4693 405 setup.nr_frames = NR_GRANT_FRAMES;
cl349@4693 406 setup.frame_list = frames;
cl349@4693 407
cl349@4693 408 BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0);
cl349@4693 409 BUG_ON(setup.status != 0);
cl349@4693 410
cl349@4693 411 for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4777 412 set_fixmap(FIX_GNTTAB_END - i, frames[i] << PAGE_SHIFT);
cl349@4693 413
cl349@4693 414 return 0;
cl349@4693 415 }
cl349@4693 416
cl349@6349 417 int
cl349@6349 418 gnttab_suspend(void)
cl349@4693 419 {
cl349@4693 420 int i;
cl349@4693 421
cl349@4693 422 for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4693 423 clear_fixmap(FIX_GNTTAB_END - i);
cl349@4693 424
cl349@4693 425 return 0;
cl349@4693 426 }
cl349@4693 427
cl349@6349 428 static int __init
cl349@6349 429 gnttab_init(void)
cl349@4693 430 {
cl349@4693 431 int i;
cl349@4693 432
cl349@4693 433 BUG_ON(gnttab_resume());
cl349@4693 434
cl349@4693 435 shared = (grant_entry_t *)fix_to_virt(FIX_GNTTAB_END);
cl349@4693 436
cl349@4693 437 for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@6349 438 gnttab_list[i] = i + 1;
cl349@4693 439
cl349@4693 440 #ifdef CONFIG_PROC_FS
cl349@4693 441 /*
cl349@4693 442 * /proc/xen/grant : used by libxc to access grant tables
cl349@4693 443 */
cl349@4693 444 if ( (grant_pde = create_xen_proc_entry("grant", 0600)) == NULL )
cl349@4693 445 {
cl349@4693 446 WPRINTK("Unable to create grant xen proc entry\n");
cl349@4693 447 return -1;
cl349@4693 448 }
cl349@4693 449
cl349@4693 450 grant_file_ops.read = grant_pde->proc_fops->read;
cl349@4693 451 grant_file_ops.write = grant_pde->proc_fops->write;
cl349@4693 452
cl349@4693 453 grant_pde->proc_fops = &grant_file_ops;
cl349@4693 454
cl349@4693 455 grant_pde->read_proc = &grant_read;
cl349@4693 456 grant_pde->write_proc = &grant_write;
cl349@4693 457 #endif
cl349@4693 458
cl349@4693 459 printk("Grant table initialized\n");
cl349@4693 460 return 0;
cl349@4693 461 }
cl349@4693 462
cl349@4693 463 __initcall(gnttab_init);