1 /* $NetBSD: xengnt.c,v 1.11 2008/11/13 18:44:51 cegger 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 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Manuel Bouyer. 17 * 4. The name of the author may not be used to endorse or promote products 18 * derived from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 * 31 */ 32 33 #include <sys/cdefs.h> 34 __KERNEL_RCSID(0, "$NetBSD: xengnt.c,v 1.11 2008/11/13 18:44:51 cegger Exp $"); 35 36 #include <sys/types.h> 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/malloc.h> 40 #include <sys/queue.h> 41 #include <sys/extent.h> 42 #include <sys/kernel.h> 43 #include <uvm/uvm.h> 44 45 #include <xen/hypervisor.h> 46 #include <xen/xen.h> 47 #include <xen/granttables.h> 48 49 /* #define XENDEBUG */ 50 #ifdef XENDEBUG 51 #define DPRINTF(x) printf x 52 #else 53 #define DPRINTF(x) 54 #endif 55 56 #define NR_GRANT_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(grant_entry_t)) 57 58 int gnt_nr_grant_frames; 59 int gnt_max_grant_frames; 60 61 /* table of free grant entries */ 62 grant_ref_t *gnt_entries; 63 int last_gnt_entry; 64 65 /* VM address of the grant table */ 66 grant_entry_t *grant_table; 67 68 static grant_ref_t xengnt_get_entry(void); 69 #define XENGNT_NO_ENTRY 0xffffffff 70 static void xengnt_free_entry(grant_ref_t); 71 static void xengnt_resume(void); 72 static int xengnt_more_entries(void); 73 74 void 75 xengnt_init() 76 { 77 struct gnttab_query_size query; 78 int rc; 79 int nr_grant_entries; 80 int i; 81 82 query.dom = DOMID_SELF; 83 rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1); 84 if ((rc < 0) || (query.status != GNTST_okay)) 85 gnt_max_grant_frames = 4; /* Legacy max number of frames */ 86 else 87 gnt_max_grant_frames = query.max_nr_frames; 88 gnt_nr_grant_frames = 0; 89 90 nr_grant_entries = 91 gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE; 92 93 grant_table = (void *)uvm_km_alloc(kernel_map, 94 gnt_max_grant_frames * PAGE_SIZE, 0, UVM_KMF_VAONLY); 95 if (grant_table == NULL) 96 panic("xengnt_init() no VM space"); 97 gnt_entries = malloc((nr_grant_entries + 1) * sizeof(grant_ref_t), 98 M_DEVBUF, M_NOWAIT); 99 if (gnt_entries == NULL) 100 panic("xengnt_init() no space for bitmask"); 101 for (i = 0; i <= nr_grant_entries; i++) 102 gnt_entries[i] = XENGNT_NO_ENTRY; 103 104 last_gnt_entry = 0; 105 xengnt_resume(); 106 107 } 108 109 static void 110 xengnt_resume() 111 { 112 int previous_nr_grant_frames = gnt_nr_grant_frames; 113 gnt_nr_grant_frames = 0; 114 while (gnt_nr_grant_frames < previous_nr_grant_frames) { 115 if (xengnt_more_entries() != 0) 116 panic("xengnt_resume: can't restore grant frames"); 117 } 118 } 119 120 /* 121 * Add another page to the grant table 122 * Returns 0 on success, ENOMEM on failure 123 */ 124 static int 125 xengnt_more_entries(void) 126 { 127 gnttab_setup_table_t setup; 128 unsigned long *pages; 129 int nframes_new = gnt_nr_grant_frames + 1; 130 int i; 131 132 if (gnt_nr_grant_frames == gnt_max_grant_frames) 133 return ENOMEM; 134 135 pages = malloc(nframes_new * sizeof(long), M_DEVBUF, M_NOWAIT); 136 if (pages == NULL) 137 return ENOMEM; 138 139 setup.dom = DOMID_SELF; 140 setup.nr_frames = nframes_new; 141 xenguest_handle(setup.frame_list) = pages; 142 143 /* 144 * setup the grant table, made of nframes_new frames 145 * and return the list of their virtual addresses 146 * in 'pages' 147 */ 148 if (HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0) 149 panic("%s: setup table failed", __func__); 150 if (setup.status != GNTST_okay) { 151 aprint_error("%s: setup table returned %d\n", 152 __func__, setup.status); 153 free(pages, M_DEVBUF); 154 return ENOMEM; 155 } 156 157 DPRINTF(("xengnt_more_entries: map 0x%lx -> %p\n", 158 pages[gnt_nr_grant_frames], 159 (char *)grant_table + gnt_nr_grant_frames * PAGE_SIZE)); 160 161 /* 162 * map between grant_table addresses and the machine addresses of 163 * the grant table frames 164 */ 165 pmap_kenter_ma(((vaddr_t)grant_table) + gnt_nr_grant_frames * PAGE_SIZE, 166 pages[gnt_nr_grant_frames] << PAGE_SHIFT, VM_PROT_WRITE); 167 168 /* 169 * add the grant entries associated to the last grant table frame 170 * and mark them as free 171 */ 172 for (i = gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE; 173 i < nframes_new * NR_GRANT_ENTRIES_PER_PAGE; 174 i++) { 175 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 176 gnt_entries[last_gnt_entry] = i; 177 last_gnt_entry++; 178 } 179 gnt_nr_grant_frames = nframes_new; 180 free(pages, M_DEVBUF); 181 return 0; 182 } 183 184 /* 185 * Returns a reference to the first free entry in grant table 186 */ 187 static grant_ref_t 188 xengnt_get_entry() 189 { 190 grant_ref_t entry; 191 int s = splvm(); 192 static struct timeval xengnt_nonmemtime; 193 static const struct timeval xengnt_nonmemintvl = {5,0}; 194 195 if (last_gnt_entry == 0) { 196 if (xengnt_more_entries()) { 197 splx(s); 198 if (ratecheck(&xengnt_nonmemtime, &xengnt_nonmemintvl)) 199 printf("xengnt_get_entry: out of grant " 200 "table entries\n"); 201 return XENGNT_NO_ENTRY; 202 } 203 } 204 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 205 last_gnt_entry--; 206 entry = gnt_entries[last_gnt_entry]; 207 gnt_entries[last_gnt_entry] = XENGNT_NO_ENTRY; 208 splx(s); 209 KASSERT(entry != XENGNT_NO_ENTRY); 210 KASSERT(last_gnt_entry >= 0 && last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 211 return entry; 212 } 213 214 /* 215 * Mark the grant table entry as free 216 */ 217 static void 218 xengnt_free_entry(grant_ref_t entry) 219 { 220 int s = splvm(); 221 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 222 KASSERT(last_gnt_entry >= 0 && last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 223 gnt_entries[last_gnt_entry] = entry; 224 last_gnt_entry++; 225 splx(s); 226 } 227 228 int 229 xengnt_grant_access(domid_t dom, paddr_t ma, int ro, grant_ref_t *entryp) 230 { 231 *entryp = xengnt_get_entry(); 232 if (__predict_false(*entryp == XENGNT_NO_ENTRY)) 233 return ENOMEM; 234 235 grant_table[*entryp].frame = ma >> PAGE_SHIFT; 236 grant_table[*entryp].domid = dom; 237 x86_lfence(); 238 grant_table[*entryp].flags = 239 GTF_permit_access | (ro ? GTF_readonly : 0); 240 return 0; 241 } 242 243 void 244 xengnt_revoke_access(grant_ref_t entry) 245 { 246 uint16_t flags, nflags; 247 248 nflags = grant_table[entry].flags; 249 250 do { 251 if ((flags = nflags) & (GTF_reading|GTF_writing)) 252 panic("xengnt_revoke_access: still in use"); 253 nflags = xen_atomic_cmpxchg16(&grant_table[entry].flags, 254 flags, 0); 255 } while (nflags != flags); 256 xengnt_free_entry(entry); 257 } 258 259 int 260 xengnt_grant_transfer(domid_t dom, grant_ref_t *entryp) 261 { 262 *entryp = xengnt_get_entry(); 263 if (__predict_false(*entryp == XENGNT_NO_ENTRY)) 264 return ENOMEM; 265 266 grant_table[*entryp].frame = 0; 267 grant_table[*entryp].domid =dom; 268 x86_lfence(); 269 grant_table[*entryp].flags = GTF_accept_transfer; 270 return 0; 271 } 272 273 paddr_t 274 xengnt_revoke_transfer(grant_ref_t entry) 275 { 276 paddr_t page; 277 uint16_t flags; 278 279 /* if the transfer has not started, free the entry and return 0 */ 280 while (!((flags = grant_table[entry].flags) & GTF_transfer_committed)) { 281 if (xen_atomic_cmpxchg16(&grant_table[entry].flags, 282 flags, 0) == flags ) { 283 xengnt_free_entry(entry); 284 return 0; 285 } 286 HYPERVISOR_yield(); 287 } 288 289 /* If transfer in progress, wait for completion */ 290 while (!((flags = grant_table[entry].flags) & GTF_transfer_completed)) 291 HYPERVISOR_yield(); 292 293 /* Read the frame number /after/ reading completion status. */ 294 __insn_barrier(); 295 page = grant_table[entry].frame; 296 if (page == 0) 297 printf("xengnt_revoke_transfer: guest sent pa 0\n"); 298 299 xengnt_free_entry(entry); 300 return page; 301 } 302 303 int 304 xengnt_status(grant_ref_t entry) 305 { 306 return (grant_table[entry].flags & (GTF_reading|GTF_writing)); 307 } 308