xen-vtx-unstable

annotate linux-2.6.11-xen-sparse/arch/xen/kernel/gnttab.c @ 5391:11dce3390a66

bitkeeper revision 1.1696 (42a81fe89VPLawDxu2WTiKLZH-Br3Q)

Make sure the grant table stuff uses locked cmpxchg instructions even when compiled
!CONFIG_SMP.

Signed-off-by: Steven Smith <sos22@cam.ac.uk>
author sos22@douglas.cl.cam.ac.uk
date Thu Jun 09 10:54:32 2005 +0000 (2005-06-09)
parents cefe173ea09b
children e982699aa8cd
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>
sos22@5391 22 #include <asm/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@4693 53 /*
cl349@4693 54 * Lock-free grant-entry allocator
cl349@4693 55 */
cl349@4693 56
cl349@4693 57 static inline int
cl349@4693 58 get_free_entry(
cl349@4693 59 void)
cl349@4693 60 {
cl349@4693 61 grant_ref_t fh, nfh = gnttab_free_head;
cl349@4693 62 do { if ( unlikely((fh = nfh) == NR_GRANT_ENTRIES) ) return -1; }
cl349@4693 63 while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh,
cl349@4693 64 gnttab_free_list[fh])) != fh) );
cl349@4693 65 return fh;
cl349@4693 66 }
cl349@4693 67
cl349@4693 68 static inline void
cl349@4693 69 put_free_entry(
cl349@4693 70 grant_ref_t ref)
cl349@4693 71 {
cl349@4693 72 grant_ref_t fh, nfh = gnttab_free_head;
cl349@4693 73 do { gnttab_free_list[ref] = fh = nfh; wmb(); }
cl349@4693 74 while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh, ref)) != fh) );
cl349@4693 75 }
cl349@4693 76
cl349@4693 77 /*
cl349@4693 78 * Public grant-issuing interface functions
cl349@4693 79 */
cl349@4693 80
cl349@4693 81 int
cl349@4693 82 gnttab_grant_foreign_access(
cl349@4693 83 domid_t domid, unsigned long frame, int readonly)
cl349@4693 84 {
cl349@4693 85 int ref;
cl349@4693 86
cl349@4693 87 if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693 88 return -ENOSPC;
cl349@4693 89
cl349@4693 90 shared[ref].frame = frame;
cl349@4693 91 shared[ref].domid = domid;
cl349@4693 92 wmb();
cl349@4693 93 shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693 94
cl349@4693 95 return ref;
cl349@4693 96 }
cl349@4693 97
cl349@4693 98 void
cl349@4693 99 gnttab_grant_foreign_access_ref(
cl349@4693 100 grant_ref_t ref, domid_t domid, unsigned long frame, int readonly)
cl349@4693 101 {
cl349@4693 102 shared[ref].frame = frame;
cl349@4693 103 shared[ref].domid = domid;
cl349@4693 104 wmb();
cl349@4693 105 shared[ref].flags = GTF_permit_access | (readonly ? GTF_readonly : 0);
cl349@4693 106 }
cl349@4693 107
cl349@4693 108
cl349@4693 109 int
cl349@4693 110 gnttab_query_foreign_access( grant_ref_t ref )
cl349@4693 111 {
cl349@4693 112 u16 nflags;
cl349@4693 113
cl349@4693 114 nflags = shared[ref].flags;
cl349@4693 115
cl349@4693 116 return ( nflags & (GTF_reading|GTF_writing) );
cl349@4693 117 }
cl349@4693 118
cl349@4693 119 void
cl349@4693 120 gnttab_end_foreign_access( grant_ref_t ref, int readonly )
cl349@4693 121 {
cl349@4693 122 u16 flags, nflags;
cl349@4693 123
cl349@4693 124 nflags = shared[ref].flags;
cl349@4693 125 do {
cl349@4693 126 if ( (flags = nflags) & (GTF_reading|GTF_writing) )
cl349@4693 127 printk(KERN_ALERT "WARNING: g.e. still in use!\n");
cl349@4693 128 }
sos22@5391 129 while ( (nflags = synch_cmpxchg(&shared[ref].flags, flags, 0)) != flags );
cl349@4693 130
cl349@4693 131 put_free_entry(ref);
cl349@4693 132 }
cl349@4693 133
cl349@4693 134 int
cl349@4693 135 gnttab_grant_foreign_transfer(
cl349@4693 136 domid_t domid, unsigned long pfn )
cl349@4693 137 {
cl349@4693 138 int ref;
cl349@4693 139
cl349@4693 140 if ( unlikely((ref = get_free_entry()) == -1) )
cl349@4693 141 return -ENOSPC;
cl349@4693 142
cl349@4693 143 shared[ref].frame = pfn;
cl349@4693 144 shared[ref].domid = domid;
cl349@4693 145 wmb();
cl349@4693 146 shared[ref].flags = GTF_accept_transfer;
cl349@4693 147
cl349@4693 148 return ref;
cl349@4693 149 }
cl349@4693 150
cl349@4693 151 void
cl349@4693 152 gnttab_grant_foreign_transfer_ref(
cl349@4693 153 grant_ref_t ref, domid_t domid, unsigned long pfn )
cl349@4693 154 {
cl349@4693 155 shared[ref].frame = pfn;
cl349@4693 156 shared[ref].domid = domid;
cl349@4693 157 wmb();
cl349@4693 158 shared[ref].flags = GTF_accept_transfer;
cl349@4693 159 }
cl349@4693 160
cl349@4693 161 unsigned long
cl349@4693 162 gnttab_end_foreign_transfer(
cl349@4693 163 grant_ref_t ref)
cl349@4693 164 {
cl349@4693 165 unsigned long frame = 0;
cl349@4693 166 u16 flags;
cl349@4693 167
cl349@4693 168 flags = shared[ref].flags;
cl349@4693 169 ASSERT(flags == (GTF_accept_transfer | GTF_transfer_committed));
cl349@4693 170
cl349@4693 171 /*
cl349@4693 172 * If a transfer is committed then wait for the frame address to appear.
cl349@4693 173 * Otherwise invalidate the grant entry against future use.
cl349@4693 174 */
cl349@4693 175 if ( likely(flags != GTF_accept_transfer) ||
sos22@5391 176 (synch_cmpxchg(&shared[ref].flags, flags, 0) != GTF_accept_transfer) )
cl349@4693 177 while ( unlikely((frame = shared[ref].frame) == 0) )
cl349@4693 178 cpu_relax();
cl349@4693 179
cl349@4693 180 put_free_entry(ref);
cl349@4693 181
cl349@4693 182 return frame;
cl349@4693 183 }
cl349@4693 184
cl349@4693 185 void
cl349@4693 186 gnttab_free_grant_references( u16 count, grant_ref_t head )
cl349@4693 187 {
cl349@4693 188 /* TODO: O(N)...? */
cl349@4693 189 grant_ref_t to_die = 0, next = head;
cl349@4693 190 int i;
cl349@4693 191
cl349@4693 192 for ( i = 0; i < count; i++ )
vh249@5272 193 {
cl349@4693 194 to_die = next;
cl349@4693 195 next = gnttab_free_list[next];
cl349@4693 196 put_free_entry( to_die );
vh249@5272 197 }
cl349@4693 198 }
cl349@4693 199
cl349@4693 200 int
cl349@4693 201 gnttab_alloc_grant_references( u16 count,
cl349@4693 202 grant_ref_t *head,
cl349@4693 203 grant_ref_t *terminal )
cl349@4693 204 {
cl349@4693 205 int i;
cl349@4693 206 grant_ref_t h = gnttab_free_head;
cl349@4693 207
cl349@4693 208 for ( i = 0; i < count; i++ )
cl349@4693 209 if ( unlikely(get_free_entry() == -1) )
cl349@4693 210 goto not_enough_refs;
cl349@4693 211
cl349@4693 212 *head = h;
cl349@4693 213 *terminal = gnttab_free_head;
cl349@4693 214
cl349@4693 215 return 0;
cl349@4693 216
cl349@4693 217 not_enough_refs:
cl349@4693 218 gnttab_free_head = h;
cl349@4693 219 return -ENOSPC;
cl349@4693 220 }
cl349@4693 221
cl349@4693 222 int
cl349@4693 223 gnttab_claim_grant_reference( grant_ref_t *private_head,
cl349@4693 224 grant_ref_t terminal )
cl349@4693 225 {
cl349@4693 226 grant_ref_t g;
cl349@4693 227 if ( unlikely((g = *private_head) == terminal) )
cl349@4693 228 return -ENOSPC;
cl349@4693 229 *private_head = gnttab_free_list[g];
cl349@4693 230 return g;
cl349@4693 231 }
cl349@4693 232
cl349@4693 233 void
cl349@4693 234 gnttab_release_grant_reference( grant_ref_t *private_head,
cl349@4693 235 grant_ref_t release )
cl349@4693 236 {
cl349@4693 237 gnttab_free_list[release] = *private_head;
cl349@4693 238 *private_head = release;
cl349@4693 239 }
cl349@4693 240
cl349@4693 241 /*
cl349@4693 242 * ProcFS operations
cl349@4693 243 */
cl349@4693 244
cl349@4693 245 #ifdef CONFIG_PROC_FS
cl349@4693 246
cl349@4693 247 static struct proc_dir_entry *grant_pde;
cl349@4693 248
cl349@4693 249 static int grant_ioctl(struct inode *inode, struct file *file,
cl349@4693 250 unsigned int cmd, unsigned long data)
cl349@4693 251 {
cl349@4693 252 int ret;
cl349@4693 253 privcmd_hypercall_t hypercall;
cl349@4693 254
cl349@4693 255 /* XXX Need safety checks here if using for anything other
cl349@4693 256 * than debugging */
cl349@4693 257 return -ENOSYS;
cl349@4693 258
cl349@4693 259 if ( cmd != IOCTL_PRIVCMD_HYPERCALL )
cl349@4693 260 return -ENOSYS;
cl349@4693 261
cl349@4693 262 if ( copy_from_user(&hypercall, (void *)data, sizeof(hypercall)) )
cl349@4693 263 return -EFAULT;
cl349@4693 264
cl349@4693 265 if ( hypercall.op != __HYPERVISOR_grant_table_op )
cl349@4693 266 return -ENOSYS;
cl349@4693 267
cl349@4693 268 /* hypercall-invoking asm taken from privcmd.c */
cl349@4693 269 __asm__ __volatile__ (
cl349@4693 270 "pushl %%ebx; pushl %%ecx; pushl %%edx; pushl %%esi; pushl %%edi; "
cl349@4693 271 "movl 4(%%eax),%%ebx ;"
cl349@4693 272 "movl 8(%%eax),%%ecx ;"
cl349@4693 273 "movl 12(%%eax),%%edx ;"
cl349@4693 274 "movl 16(%%eax),%%esi ;"
cl349@4693 275 "movl 20(%%eax),%%edi ;"
cl349@4693 276 "movl (%%eax),%%eax ;"
cl349@4693 277 TRAP_INSTR "; "
cl349@4693 278 "popl %%edi; popl %%esi; popl %%edx; popl %%ecx; popl %%ebx"
cl349@4693 279 : "=a" (ret) : "0" (&hypercall) : "memory" );
cl349@4693 280
cl349@4693 281 return ret;
cl349@4693 282 }
cl349@4693 283
cl349@4693 284 static struct file_operations grant_file_ops = {
cl349@4693 285 ioctl: grant_ioctl,
cl349@4693 286 };
cl349@4693 287
cl349@4693 288 static int grant_read(char *page, char **start, off_t off,
cl349@4693 289 int count, int *eof, void *data)
cl349@4693 290 {
cl349@4693 291 int len;
cl349@4693 292 unsigned int i;
cl349@4693 293 grant_entry_t *gt;
cl349@4693 294
cl349@4693 295 gt = (grant_entry_t *)shared;
cl349@4693 296 len = 0;
cl349@4693 297
cl349@4693 298 for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@4693 299 /* TODO: safety catch here until this can handle >PAGE_SIZE output */
cl349@4693 300 if (len > (PAGE_SIZE - 200))
cl349@4693 301 {
cl349@4693 302 len += sprintf( page + len, "Truncated.\n");
cl349@4693 303 break;
cl349@4693 304 }
cl349@4693 305
cl349@4693 306 if ( gt[i].flags )
cl349@4693 307 len += sprintf( page + len,
cl349@4693 308 "Grant: ref (0x%x) flags (0x%hx) dom (0x%hx) frame (0x%x)\n",
cl349@4693 309 i,
cl349@4693 310 gt[i].flags,
cl349@4693 311 gt[i].domid,
cl349@4693 312 gt[i].frame );
cl349@4693 313
cl349@4693 314 *eof = 1;
cl349@4693 315 return len;
cl349@4693 316 }
cl349@4693 317
cl349@4693 318 static int grant_write(struct file *file, const char __user *buffer,
cl349@4693 319 unsigned long count, void *data)
cl349@4693 320 {
cl349@4693 321 /* TODO: implement this */
cl349@4693 322 return -ENOSYS;
cl349@4693 323 }
cl349@4693 324
cl349@4693 325 #endif /* CONFIG_PROC_FS */
cl349@4693 326
cl349@4693 327 int gnttab_resume(void)
cl349@4693 328 {
cl349@4693 329 gnttab_setup_table_t setup;
cl349@4693 330 unsigned long frames[NR_GRANT_FRAMES];
cl349@4693 331 int i;
cl349@4693 332
cl349@4693 333 setup.dom = DOMID_SELF;
cl349@4693 334 setup.nr_frames = NR_GRANT_FRAMES;
cl349@4693 335 setup.frame_list = frames;
cl349@4693 336
cl349@4693 337 BUG_ON(HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0);
cl349@4693 338 BUG_ON(setup.status != 0);
cl349@4693 339
cl349@4693 340 for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4777 341 set_fixmap(FIX_GNTTAB_END - i, frames[i] << PAGE_SHIFT);
cl349@4693 342
cl349@4693 343 return 0;
cl349@4693 344 }
cl349@4693 345
cl349@4693 346 int gnttab_suspend(void)
cl349@4693 347 {
cl349@4693 348 int i;
cl349@4693 349
cl349@4693 350 for ( i = 0; i < NR_GRANT_FRAMES; i++ )
cl349@4693 351 clear_fixmap(FIX_GNTTAB_END - i);
cl349@4693 352
cl349@4693 353 return 0;
cl349@4693 354 }
cl349@4693 355
cl349@4693 356 static int __init gnttab_init(void)
cl349@4693 357 {
cl349@4693 358 int i;
cl349@4693 359
cl349@4693 360 BUG_ON(gnttab_resume());
cl349@4693 361
cl349@4693 362 shared = (grant_entry_t *)fix_to_virt(FIX_GNTTAB_END);
cl349@4693 363
cl349@4693 364 for ( i = 0; i < NR_GRANT_ENTRIES; i++ )
cl349@4693 365 gnttab_free_list[i] = i + 1;
cl349@4693 366
cl349@4693 367 #ifdef CONFIG_PROC_FS
cl349@4693 368 /*
cl349@4693 369 * /proc/xen/grant : used by libxc to access grant tables
cl349@4693 370 */
cl349@4693 371 if ( (grant_pde = create_xen_proc_entry("grant", 0600)) == NULL )
cl349@4693 372 {
cl349@4693 373 WPRINTK("Unable to create grant xen proc entry\n");
cl349@4693 374 return -1;
cl349@4693 375 }
cl349@4693 376
cl349@4693 377 grant_file_ops.read = grant_pde->proc_fops->read;
cl349@4693 378 grant_file_ops.write = grant_pde->proc_fops->write;
cl349@4693 379
cl349@4693 380 grant_pde->proc_fops = &grant_file_ops;
cl349@4693 381
cl349@4693 382 grant_pde->read_proc = &grant_read;
cl349@4693 383 grant_pde->write_proc = &grant_write;
cl349@4693 384 #endif
cl349@4693 385
cl349@4693 386 printk("Grant table initialized\n");
cl349@4693 387 return 0;
cl349@4693 388 }
cl349@4693 389
cl349@4693 390 __initcall(gnttab_init);