xen-vtx-unstable

annotate linux-2.6-xen-sparse/arch/xen/kernel/gnttab.c @ 6346:96f1f6c71089

Update gnttab_free_callback_list locking.
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
author cl349@firebug.cl.cam.ac.uk
date Tue Aug 23 09:24:46 2005 +0000 (2005-08-23)
parents af9e3ae3a9b1
children 4956ea5b1e34
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@4693 43 EXPORT_SYMBOL(gnttab_claim_grant_reference);
cl349@4693 44 EXPORT_SYMBOL(gnttab_release_grant_reference);
cl349@4693 45 EXPORT_SYMBOL(gnttab_grant_foreign_access_ref);
cl349@4693 46 EXPORT_SYMBOL(gnttab_grant_foreign_transfer_ref);
cl349@4693 47
cl349@4693 48 static grant_ref_t gnttab_free_list[NR_GRANT_ENTRIES];
cl349@4693 49 static grant_ref_t gnttab_free_head;
cl349@4693 50
cl349@4693 51 static grant_entry_t *shared;
cl349@4693 52
cl349@6339 53 static struct gnttab_free_callback *gnttab_free_callback_list = NULL;
cl349@6345 54 static spinlock_t gnttab_free_callback_list_lock = SPIN_LOCK_UNLOCKED;
cl349@6339 55
cl349@4693 56 /*
cl349@4693 57 * Lock-free grant-entry allocator
cl349@4693 58 */
cl349@4693 59
cl349@4693 60 static inline int
cl349@4693 61 get_free_entry(
cl349@4693 62 void)
cl349@4693 63 {
cl349@4693 64 grant_ref_t fh, nfh = gnttab_free_head;
cl349@4693 65 do { if ( unlikely((fh = nfh) == NR_GRANT_ENTRIES) ) return -1; }
cl349@4693 66 while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh,
cl349@4693 67 gnttab_free_list[fh])) != fh) );
cl349@4693 68 return fh;
cl349@4693 69 }
cl349@4693 70
cl349@6346 71 static void do_free_callbacks(unsigned long flags)
cl349@6339 72 {
cl349@6346 73 struct gnttab_free_callback *callback = gnttab_free_callback_list, *next;
cl349@6339 74 gnttab_free_callback_list = NULL;
cl349@6346 75 spin_unlock_irqrestore(&gnttab_free_callback_list_lock, flags);
cl349@6339 76 while (callback) {
cl349@6342 77 next = callback->next;
cl349@6342 78 callback->next = NULL;
cl349@6342 79 callback->fn(callback->arg);
cl349@6342 80 callback = next;
cl349@6339 81 }
cl349@6339 82 }
cl349@6339 83
cl349@4693 84 static inline void
cl349@4693 85 put_free_entry(
cl349@4693 86 grant_ref_t ref)
cl349@4693 87 {
cl349@4693 88 grant_ref_t fh, nfh = gnttab_free_head;
cl349@6346 89 unsigned long flags;
cl349@4693 90 do { gnttab_free_list[ref] = fh = nfh; wmb(); }
cl349@4693 91 while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh, ref)) != fh) );
cl349@6346 92 spin_lock_irqsave(&gnttab_free_callback_list_lock, flags);
cl349@6339 93 if ( unlikely(gnttab_free_callback_list) )
cl349@6346 94 do_free_callbacks(flags);
cl349@6346 95 else
cl349@6346 96 spin_unlock_irqrestore(&gnttab_free_callback_list_lock, flags);
cl349@4693 97 }
cl349@4693 98
cl349@4693 99 /*
cl349@4693 100 * Public grant-issuing interface functions
cl349@4693 101 */
cl349@4693 102
cl349@4693 103 int
cl349@4693 104 gnttab_grant_foreign_access(
cl349@4693 105 domid_t domid, unsigned long frame, int readonly)
cl349@4693 106 {
cl349@4693 107 int ref;
cl349@4693 108
cl349@4693 109 if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693 110 return -ENOSPC;
cl349@4693 111
cl349@4693 112 shared[ref].frame = frame;
cl349@4693 113 shared[ref].domid = domid;
cl349@4693 114 wmb();
cl349@4693 115 shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693 116
cl349@4693 117 return ref;
cl349@4693 118 }
cl349@4693 119
cl349@4693 120 void
cl349@4693 121 gnttab_grant_foreign_access_ref(
cl349@4693 122 grant_ref_t ref, domid_t domid, unsigned long frame, int readonly)
cl349@4693 123 {
cl349@4693 124 shared[ref].frame = frame;
cl349@4693 125 shared[ref].domid = domid;
cl349@4693 126 wmb();
cl349@4693 127 shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693 128 }
cl349@4693 129
cl349@4693 130
cl349@4693 131 int
cl349@4693 132 gnttab_query_foreign_access( grant_ref_t ref )
cl349@4693 133 {
cl349@4693 134 u16 nflags;
cl349@4693 135
cl349@4693 136 nflags = shared[ref].flags;
cl349@4693 137
cl349@4693 138 return ( nflags & (GTF_reading|GTF_writing) );
cl349@4693 139 }
cl349@4693 140
cl349@4693 141 void
cl349@4693 142 gnttab_end_foreign_access( grant_ref_t ref, int readonly )
cl349@4693 143 {
cl349@4693 144 u16 flags, nflags;
cl349@4693 145
cl349@4693 146 nflags = shared[ref].flags;
cl349@4693 147 do {
cl349@4693 148 if ( (flags = nflags) & (GTF_reading|GTF_writing) )
cl349@4693 149 printk(KERN_ALERT "WARNING: g.e. still in use!\n");
cl349@4693 150 }
sos22@5391 151 while ( (nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) != flags );
cl349@4693 152
cl349@4693 153 put_free_entry(ref);
cl349@4693 154 }
cl349@4693 155
cl349@4693 156 int
cl349@4693 157 gnttab_grant_foreign_transfer(
cl349@4693 158 domid_t domid, unsigned long pfn )
cl349@4693 159 {
cl349@4693 160 int ref;
cl349@4693 161
cl349@4693 162 if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693 163 return -ENOSPC;
cl349@4693 164
cl349@4693 165 shared[ref].frame = pfn;
cl349@4693 166 shared[ref].domid = domid;
cl349@4693 167 wmb();
cl349@4693 168 shared[ref].flags = GTF_accept_transfer;
cl349@4693 169
cl349@4693 170 return ref;
cl349@4693 171 }
cl349@4693 172
cl349@4693 173 void
cl349@4693 174 gnttab_grant_foreign_transfer_ref(
cl349@4693 175 grant_ref_t ref, domid_t domid, unsigned long pfn )
cl349@4693 176 {
cl349@4693 177 shared[ref].frame = pfn;
cl349@4693 178 shared[ref].domid = domid;
cl349@4693 179 wmb();
cl349@4693 180 shared[ref].flags = GTF_accept_transfer;
cl349@4693 181 }
cl349@4693 182
cl349@4693 183 unsigned long
cl349@4693 184 gnttab_end_foreign_transfer(
cl349@4693 185 grant_ref_t ref)
cl349@4693 186 {
cl349@4693 187 unsigned long frame = 0;
cl349@4693 188 u16 flags;
cl349@4693 189
cl349@4693 190 flags = shared[ref].flags;
vh249@5828 191 #ifdef CONFIG_XEN_NETDEV_GRANT_RX
vh249@5828 192 /*
vh249@5828 193 * But can't flags == (GTF_accept_transfer | GTF_transfer_completed)
vh249@5828 194 * if gnttab_donate executes without interruption???
vh249@5828 195 */
vh249@5828 196 #else
cl349@4693 197 ASSERT(flags == (GTF_accept_transfer | GTF_transfer_committed));
vh249@5828 198 #endif
cl349@4693 199 /*
cl349@4693 200 * If a transfer is committed then wait for the frame address to appear.
cl349@4693 201 * Otherwise invalidate the grant entry against future use.
cl349@4693 202 */
cl349@4693 203 if ( likely(flags != GTF_accept_transfer) ||
sos22@5391 204 (synch_cmpxchg(&shared[ref].flags, flags, 0) != GTF_accept_transfer) )
cl349@4693 205 while ( unlikely((frame = shared[ref].frame) == 0) )
cl349@4693 206 cpu_relax();
cl349@4693 207
cl349@4693 208 put_free_entry(ref);
cl349@4693 209
cl349@4693 210 return frame;
cl349@4693 211 }
cl349@4693 212
cl349@4693 213 void
cl349@6339 214 gnttab_free_grant_reference( grant_ref_t ref )
cl349@6339 215 {
cl349@6339 216
cl349@6339 217 put_free_entry(ref);
cl349@6339 218 }
cl349@6339 219
cl349@6339 220 void
cl349@6339 221 gnttab_free_grant_references( grant_ref_t *head,
cl349@6339 222 grant_ref_t terminal )
cl349@4693 223 {
cl349@4693 224 /* TODO: O(N)...? */
cl349@6339 225 grant_ref_t ref;
cl349@4693 226
cl349@6339 227 while (*head != terminal) {
cl349@6339 228 ref = *head;
cl349@6339 229 *head = gnttab_free_list[*head];
cl349@6339 230 put_free_entry(ref);
vh249@5272 231 }
cl349@4693 232 }
cl349@4693 233
cl349@4693 234 int
cl349@4693 235 gnttab_alloc_grant_references( u16 count,
cl349@4693 236 grant_ref_t *head,
cl349@4693 237 grant_ref_t *terminal )
cl349@4693 238 {
cl349@4693 239 int i;
cl349@4693 240 grant_ref_t h = gnttab_free_head;
cl349@4693 241
cl349@4693 242 for ( i = 0; i < count; i++ )
cl349@4693 243 if ( unlikely(get_free_entry() == -1) )
cl349@4693 244 goto not_enough_refs;
cl349@4693 245
cl349@4693 246 *head = h;
cl349@4693 247 *terminal = gnttab_free_head;
cl349@4693 248
cl349@4693 249 return 0;
cl349@4693 250
cl349@4693 251 not_enough_refs:
cl349@4693 252 gnttab_free_head = h;
cl349@4693 253 return -ENOSPC;
cl349@4693 254 }
cl349@4693 255
cl349@4693 256 int
cl349@4693 257 gnttab_claim_grant_reference( grant_ref_t *private_head,
cl349@4693 258 grant_ref_t terminal )
cl349@4693 259 {
cl349@4693 260 grant_ref_t g;
cl349@4693 261 if ( unlikely((g = *private_head) == terminal) )
cl349@4693 262 return -ENOSPC;
cl349@4693 263 *private_head = gnttab_free_list[g];
cl349@4693 264 return g;
cl349@4693 265 }
cl349@4693 266
cl349@4693 267 void
cl349@4693 268 gnttab_release_grant_reference( grant_ref_t *private_head,
cl349@4693 269 grant_ref_t release )
cl349@4693 270 {
cl349@4693 271 gnttab_free_list[release] = *private_head;
cl349@4693 272 *private_head = release;
cl349@4693 273 }
cl349@4693 274
cl349@6339 275 void
cl349@6339 276 gnttab_request_free_callback(struct gnttab_free_callback *callback,
cl349@6342 277 void (*fn)(void *), void *arg)
cl349@6339 278 {
cl349@6346 279 unsigned long flags;
cl349@6342 280 if (callback->next)
cl349@6342 281 return;
cl349@6342 282 callback->fn = fn;
cl349@6342 283 callback->arg = arg;
cl349@6346 284 spin_lock_irqsave(&gnttab_free_callback_list_lock, flags);
cl349@6339 285 callback->next = gnttab_free_callback_list;
cl349@6339 286 gnttab_free_callback_list = callback;
cl349@6346 287 spin_unlock_irqrestore(&gnttab_free_callback_list_lock, flags);
cl349@6339 288 }
cl349@6339 289
cl349@4693 290 /*
cl349@4693 291 * ProcFS operations
cl349@4693 292 */
cl349@4693 293
cl349@4693 294 #ifdef CONFIG_PROC_FS
cl349@4693 295
cl349@4693 296 static struct proc_dir_entry *grant_pde;
cl349@4693 297
cl349@4693 298 static int grant_ioctl(struct inode *inode, struct file *file,
cl349@4693 299 unsigned int cmd, unsigned long data)
cl349@4693 300 {
cl349@4693 301 int ret;
cl349@4693 302 privcmd_hypercall_t hypercall;
cl349@4693 303
cl349@4693 304 /* XXX Need safety checks here if using for anything other
cl349@4693 305 * than debugging */
cl349@4693 306 return -ENOSYS;
cl349@4693 307
cl349@4693 308 if ( cmd != IOCTL_PRIVCMD_HYPERCALL )
cl349@4693 309 return -ENOSYS;
cl349@4693 310
cl349@4693 311 if ( copy_from_user(&hypercall, (void *)data, sizeof(hypercall)) )
cl349@4693 312 return -EFAULT;
cl349@4693 313
cl349@4693 314 if ( hypercall.op != __HYPERVISOR_grant_table_op )
cl349@4693 315 return -ENOSYS;
cl349@4693 316
cl349@4693 317 /* hypercall-invoking asm taken from privcmd.c */
cl349@4693 318 __asm__ __volatile__ (
cl349@4693 319 "pushl %%ebx; pushl %%ecx; pushl %%edx; pushl %%esi; pushl %%edi; "
cl349@4693 320 "movl 4(%%eax),%%ebx ;"
cl349@4693 321 "movl 8(%%eax),%%ecx ;"
cl349@4693 322 "movl 12(%%eax),%%edx ;"
cl349@4693 323 "movl 16(%%eax),%%esi ;"
cl349@4693 324 "movl 20(%%eax),%%edi ;"
cl349@4693 325 "movl (%%eax),%%eax ;"
cl349@4693 326 TRAP_INSTR "; "
cl349@4693 327 "popl %%edi; popl %%esi; popl %%edx; popl %%ecx; popl %%ebx"
cl349@4693 328 : "=a" (ret) : "0" (&hypercall) : "memory" );
cl349@4693 329
cl349@4693 330 return ret;
cl349@4693 331 }
cl349@4693 332
cl349@4693 333 static struct file_operations grant_file_ops = {
cl349@4693 334 ioctl: grant_ioctl,
cl349@4693 335 };
cl349@4693 336
cl349@4693 337 static int grant_read(char *page, char **start, off_t off,
cl349@4693 338 int count, int *eof, void *data)
cl349@4693 339 {
cl349@4693 340 int len;
cl349@4693 341 unsigned int i;
cl349@4693 342 grant_entry_t *gt;
cl349@4693 343
cl349@4693 344 gt = (grant_entry_t *)shared;
cl349@4693 345 len = 0;
cl349@4693 346
cl349@4693 347 for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@4693 348 /* TODO: safety catch here until this can handle >PAGE_SIZE output */
cl349@4693 349 if (len > (PAGE_SIZE - 200))
cl349@4693 350 {
cl349@4693 351 len += sprintf( page + len, "Truncated.\n");
cl349@4693 352 break;
cl349@4693 353 }
cl349@4693 354
cl349@4693 355 if ( gt[i].flags )
cl349@4693 356 len += sprintf( page + len,
cl349@4693 357 "Grant: ref (0x%x) flags (0x%hx) dom (0x%hx) frame (0x%x)\n",
cl349@4693 358 i,
cl349@4693 359 gt[i].flags,
cl349@4693 360 gt[i].domid,
cl349@4693 361 gt[i].frame );
cl349@4693 362
cl349@4693 363 *eof = 1;
cl349@4693 364 return len;
cl349@4693 365 }
cl349@4693 366
cl349@4693 367 static int grant_write(struct file *file, const char __user *buffer,
cl349@4693 368 unsigned long count, void *data)
cl349@4693 369 {
cl349@4693 370 /* TODO: implement this */
cl349@4693 371 return -ENOSYS;
cl349@4693 372 }
cl349@4693 373
cl349@4693 374 #endif /* CONFIG_PROC_FS */
cl349@4693 375
cl349@4693 376 int gnttab_resume(void)
cl349@4693 377 {
cl349@4693 378 gnttab_setup_table_t setup;
cl349@4693 379 unsigned long frames[NR_GRANT_FRAMES];
cl349@4693 380 int i;
cl349@4693 381
cl349@4693 382 setup.dom = DOMID_SELF;
cl349@4693 383 setup.nr_frames = NR_GRANT_FRAMES;
cl349@4693 384 setup.frame_list = frames;
cl349@4693 385
cl349@4693 386 BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0);
cl349@4693 387 BUG_ON(setup.status != 0);
cl349@4693 388
cl349@4693 389 for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4777 390 set_fixmap(FIX_GNTTAB_END - i, frames[i] << PAGE_SHIFT);
cl349@4693 391
cl349@4693 392 return 0;
cl349@4693 393 }
cl349@4693 394
cl349@4693 395 int gnttab_suspend(void)
cl349@4693 396 {
cl349@4693 397 int i;
cl349@4693 398
cl349@4693 399 for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4693 400 clear_fixmap(FIX_GNTTAB_END - i);
cl349@4693 401
cl349@4693 402 return 0;
cl349@4693 403 }
cl349@4693 404
cl349@4693 405 static int __init gnttab_init(void)
cl349@4693 406 {
cl349@4693 407 int i;
cl349@4693 408
cl349@4693 409 BUG_ON(gnttab_resume());
cl349@4693 410
cl349@4693 411 shared = (grant_entry_t *)fix_to_virt(FIX_GNTTAB_END);
cl349@4693 412
cl349@4693 413 for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@4693 414 gnttab_free_list[i] = i + 1;
cl349@4693 415
cl349@4693 416 #ifdef CONFIG_PROC_FS
cl349@4693 417 /*
cl349@4693 418 * /proc/xen/grant : used by libxc to access grant tables
cl349@4693 419 */
cl349@4693 420 if ( (grant_pde = create_xen_proc_entry("grant", 0600)) == NULL )
cl349@4693 421 {
cl349@4693 422 WPRINTK("Unable to create grant xen proc entry\n");
cl349@4693 423 return -1;
cl349@4693 424 }
cl349@4693 425
cl349@4693 426 grant_file_ops.read = grant_pde->proc_fops->read;
cl349@4693 427 grant_file_ops.write = grant_pde->proc_fops->write;
cl349@4693 428
cl349@4693 429 grant_pde->proc_fops = &grant_file_ops;
cl349@4693 430
cl349@4693 431 grant_pde->read_proc = &grant_read;
cl349@4693 432 grant_pde->write_proc = &grant_write;
cl349@4693 433 #endif
cl349@4693 434
cl349@4693 435 printk("Grant table initialized\n");
cl349@4693 436 return 0;
cl349@4693 437 }
cl349@4693 438
cl349@4693 439 __initcall(gnttab_init);