1 /* $NetBSD: xengnt.c,v 1.25 2012/10/24 13:07:46 royger Exp $ */ 2 3 /* 4 * Copyright (c) 2006 Manuel Bouyer. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28 #include <sys/cdefs.h> 29 __KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1.25 2012/10/24 13:07:46 royger Exp $"); 30 31 #include <sys/types.h> 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/malloc.h> 35 #include <sys/queue.h> 36 #include <sys/extent.h> 37 #include <sys/kernel.h> 38 #include <sys/mutex.h> 39 #include <uvm/uvm.h> 40 41 #include <xen/hypervisor.h> 42 #include <xen/xen.h> 43 #include <xen/granttables.h> 44 45 /* #define XENDEBUG */ 46 #ifdef XENDEBUG 47 #define DPRINTF(x) printf x 48 #else 49 #define DPRINTF(x) 50 #endif 51 52 #define NR_GRANT_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(grant_entry_t)) 53 54 /* External tools reserve first few grant table entries. */ 55 #define NR_RESERVED_ENTRIES 8 56 57 /* Current number of frames making up the grant table */ 58 int gnt_nr_grant_frames; 59 /* Maximum number of frames that can make up the grant table */ 60 int gnt_max_grant_frames; 61 62 /* table of free grant entries */ 63 grant_ref_t *gnt_entries; 64 /* last free entry */ 65 int last_gnt_entry; 66 /* empty entry in the list */ 67 #define XENGNT_NO_ENTRY 0xffffffff 68 69 /* VM address of the grant table */ 70 grant_entry_t *grant_table; 71 kmutex_t grant_lock; 72 73 static grant_ref_t xengnt_get_entry(void); 74 static void xengnt_free_entry(grant_ref_t); 75 static int xengnt_more_entries(void); 76 77 void 78 xengnt_init(void) 79 { 80 struct gnttab_query_size query; 81 int rc; 82 int nr_grant_entries; 83 int i; 84 85 query.dom = DOMID_SELF; 86 rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1); 87 if ((rc < 0) || (query.status != GNTST_okay)) 88 gnt_max_grant_frames = 4; /* Legacy max number of frames */ 89 else 90 gnt_max_grant_frames = query.max_nr_frames; 91 gnt_nr_grant_frames = 0; 92 93 nr_grant_entries = 94 gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE; 95 96 grant_table = (void *)uvm_km_alloc(kernel_map, 97 gnt_max_grant_frames * PAGE_SIZE, 0, UVM_KMF_VAONLY); 98 if (grant_table == NULL) 99 panic("xengnt_init() no VM space"); 100 gnt_entries = malloc((nr_grant_entries + 1) * sizeof(grant_ref_t), 101 M_DEVBUF, M_NOWAIT); 102 if (gnt_entries == NULL) 103 panic("xengnt_init() no space for bitmask"); 104 for (i = 0; i <= nr_grant_entries; i++) 105 gnt_entries[i] = XENGNT_NO_ENTRY; 106 107 mutex_init(&grant_lock, MUTEX_DEFAULT, IPL_VM); 108 109 xengnt_resume(); 110 111 } 112 113 /* 114 * Resume grant table state 115 */ 116 bool 117 xengnt_resume(void) 118 { 119 int previous_nr_grant_frames = gnt_nr_grant_frames; 120 121 last_gnt_entry = 0; 122 gnt_nr_grant_frames = 0; 123 124 mutex_enter(&grant_lock); 125 while (gnt_nr_grant_frames < previous_nr_grant_frames) { 126 if (xengnt_more_entries() != 0) 127 panic("xengnt_resume: can't restore grant frames"); 128 } 129 mutex_exit(&grant_lock); 130 return true; 131 } 132 133 /* 134 * Suspend grant table state 135 */ 136 bool 137 xengnt_suspend(void) { 138 139 int i; 140 141 mutex_enter(&grant_lock); 142 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 143 144 for (i = 0; i < last_gnt_entry; i++) { 145 /* invalidate all grant entries (necessary for resume) */ 146 gnt_entries[i] = XENGNT_NO_ENTRY; 147 } 148 149 /* Remove virtual => machine mapping */ 150 pmap_kremove((vaddr_t)grant_table, gnt_nr_grant_frames * PAGE_SIZE); 151 pmap_update(pmap_kernel()); 152 mutex_exit(&grant_lock); 153 return true; 154 } 155 156 157 /* 158 * Add another page to the grant table 159 * Returns 0 on success, ENOMEM on failure 160 */ 161 static int 162 xengnt_more_entries(void) 163 { 164 gnttab_setup_table_t setup; 165 u_long *pages; 166 int nframes_new = gnt_nr_grant_frames + 1; 167 int i, start_gnt; 168 KASSERT(mutex_owned(&grant_lock)); 169 170 if (gnt_nr_grant_frames == gnt_max_grant_frames) 171 return ENOMEM; 172 173 pages = malloc(nframes_new * sizeof(u_long), M_DEVBUF, M_NOWAIT); 174 if (pages == NULL) 175 return ENOMEM; 176 177 setup.dom = DOMID_SELF; 178 setup.nr_frames = nframes_new; 179 set_xen_guest_handle(setup.frame_list, pages); 180 181 /* 182 * setup the grant table, made of nframes_new frames 183 * and return the list of their virtual addresses 184 * in 'pages' 185 */ 186 if (HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0) 187 panic("%s: setup table failed", __func__); 188 if (setup.status != GNTST_okay) { 189 aprint_error("%s: setup table returned %d\n", 190 __func__, setup.status); 191 free(pages, M_DEVBUF); 192 return ENOMEM; 193 } 194 195 DPRINTF(("xengnt_more_entries: map 0x%lx -> %p\n", 196 pages[gnt_nr_grant_frames], 197 (char *)grant_table + gnt_nr_grant_frames * PAGE_SIZE)); 198 199 /* 200 * map between grant_table addresses and the machine addresses of 201 * the grant table frames 202 */ 203 pmap_kenter_ma(((vaddr_t)grant_table) + gnt_nr_grant_frames * PAGE_SIZE, 204 ((paddr_t)pages[gnt_nr_grant_frames]) << PAGE_SHIFT, 205 VM_PROT_WRITE, 0); 206 pmap_update(pmap_kernel()); 207 208 /* 209 * add the grant entries associated to the last grant table frame 210 * and mark them as free. Prevent using the first grants (from 0 to 8) 211 * since they are used by the tools. 212 */ 213 start_gnt = (gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE) < 214 (NR_RESERVED_ENTRIES + 1) ? 215 (NR_RESERVED_ENTRIES + 1) : 216 (gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 217 for (i = start_gnt; 218 i < nframes_new * NR_GRANT_ENTRIES_PER_PAGE; 219 i++) { 220 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 221 gnt_entries[last_gnt_entry] = i; 222 last_gnt_entry++; 223 } 224 gnt_nr_grant_frames = nframes_new; 225 free(pages, M_DEVBUF); 226 return 0; 227 } 228 229 /* 230 * Returns a reference to the first free entry in grant table 231 */ 232 static grant_ref_t 233 xengnt_get_entry(void) 234 { 235 grant_ref_t entry; 236 static struct timeval xengnt_nonmemtime; 237 static const struct timeval xengnt_nonmemintvl = {5,0}; 238 239 if (last_gnt_entry == 0) { 240 if (xengnt_more_entries()) { 241 if (ratecheck(&xengnt_nonmemtime, &xengnt_nonmemintvl)) 242 printf("xengnt_get_entry: out of grant " 243 "table entries\n"); 244 return XENGNT_NO_ENTRY; 245 } 246 } 247 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 248 last_gnt_entry--; 249 entry = gnt_entries[last_gnt_entry]; 250 gnt_entries[last_gnt_entry] = XENGNT_NO_ENTRY; 251 KASSERT(entry != XENGNT_NO_ENTRY && entry > NR_RESERVED_ENTRIES); 252 KASSERT(last_gnt_entry >= 0); 253 KASSERT(last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 254 return entry; 255 } 256 257 /* 258 * Mark the grant table entry as free 259 */ 260 static void 261 xengnt_free_entry(grant_ref_t entry) 262 { 263 mutex_enter(&grant_lock); 264 KASSERT(entry > NR_RESERVED_ENTRIES); 265 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 266 KASSERT(last_gnt_entry >= 0); 267 KASSERT(last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 268 gnt_entries[last_gnt_entry] = entry; 269 last_gnt_entry++; 270 mutex_exit(&grant_lock); 271 } 272 273 int 274 xengnt_grant_access(domid_t dom, paddr_t ma, int ro, grant_ref_t *entryp) 275 { 276 mutex_enter(&grant_lock); 277 278 *entryp = xengnt_get_entry(); 279 if (__predict_false(*entryp == XENGNT_NO_ENTRY)) { 280 mutex_exit(&grant_lock); 281 return ENOMEM; 282 } 283 284 grant_table[*entryp].frame = ma >> PAGE_SHIFT; 285 grant_table[*entryp].domid = dom; 286 /* 287 * ensure that the above values reach global visibility 288 * before permitting frame's access (done when we set flags) 289 */ 290 xen_rmb(); 291 grant_table[*entryp].flags = 292 GTF_permit_access | (ro ? GTF_readonly : 0); 293 mutex_exit(&grant_lock); 294 return 0; 295 } 296 297 void 298 xengnt_revoke_access(grant_ref_t entry) 299 { 300 uint16_t flags, nflags; 301 302 nflags = grant_table[entry].flags; 303 304 do { 305 if ((flags = nflags) & (GTF_reading|GTF_writing)) 306 panic("xengnt_revoke_access: still in use"); 307 nflags = xen_atomic_cmpxchg16(&grant_table[entry].flags, 308 flags, 0); 309 } while (nflags != flags); 310 xengnt_free_entry(entry); 311 } 312 313 int 314 xengnt_grant_transfer(domid_t dom, grant_ref_t *entryp) 315 { 316 mutex_enter(&grant_lock); 317 318 *entryp = xengnt_get_entry(); 319 if (__predict_false(*entryp == XENGNT_NO_ENTRY)) { 320 mutex_exit(&grant_lock); 321 return ENOMEM; 322 } 323 324 grant_table[*entryp].frame = 0; 325 grant_table[*entryp].domid = dom; 326 /* 327 * ensure that the above values reach global visibility 328 * before permitting frame's transfer (done when we set flags) 329 */ 330 xen_rmb(); 331 grant_table[*entryp].flags = GTF_accept_transfer; 332 mutex_exit(&grant_lock); 333 return 0; 334 } 335 336 paddr_t 337 xengnt_revoke_transfer(grant_ref_t entry) 338 { 339 paddr_t page; 340 uint16_t flags; 341 342 /* if the transfer has not started, free the entry and return 0 */ 343 while (!((flags = grant_table[entry].flags) & GTF_transfer_committed)) { 344 if (xen_atomic_cmpxchg16(&grant_table[entry].flags, 345 flags, 0) == flags ) { 346 xengnt_free_entry(entry); 347 return 0; 348 } 349 HYPERVISOR_yield(); 350 } 351 352 /* If transfer in progress, wait for completion */ 353 while (!((flags = grant_table[entry].flags) & GTF_transfer_completed)) 354 HYPERVISOR_yield(); 355 356 /* Read the frame number /after/ reading completion status. */ 357 __insn_barrier(); 358 page = grant_table[entry].frame; 359 if (page == 0) 360 printf("xengnt_revoke_transfer: guest sent pa 0\n"); 361 362 xengnt_free_entry(entry); 363 return page; 364 } 365 366 int 367 xengnt_status(grant_ref_t entry) 368 { 369 return (grant_table[entry].flags & (GTF_reading|GTF_writing)); 370 } 371