1 /* $NetBSD: xengnt.c,v 1.6 2008/02/17 14:03:16 bouyer 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 1.6 2008/02/17 14:03:16 bouyer 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 static int 121 xengnt_more_entries() 122 { 123 gnttab_setup_table_t setup; 124 unsigned long *pages; 125 int nframes_new = gnt_nr_grant_frames + 1; 126 int i; 127 128 if (gnt_nr_grant_frames == gnt_max_grant_frames) 129 return ENOMEM; 130 131 pages = malloc(nframes_new * sizeof(long), M_DEVBUF, M_NOWAIT); 132 if (pages == NULL) 133 return ENOMEM; 134 135 setup.dom = DOMID_SELF; 136 setup.nr_frames = nframes_new; 137 setup.frame_list = pages; 138 139 if (HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1) != 0) 140 panic("xengnt_more_entries: setup table failed"); 141 if (setup.status != 0) { 142 printf("xengnt_more_entries: setup table returned %d\n", 143 setup.status); 144 return ENOMEM; 145 } 146 147 DPRINTF(("xengnt_more_entries: map 0x%lx -> %p\n", 148 pages[gnt_nr_grant_frames], 149 (char *)grant_table + gnt_nr_grant_frames * PAGE_SIZE)); 150 151 pmap_kenter_ma(((vaddr_t)grant_table) + gnt_nr_grant_frames * PAGE_SIZE, 152 pages[gnt_nr_grant_frames] << PAGE_SHIFT, VM_PROT_WRITE); 153 154 155 for (i = gnt_nr_grant_frames * NR_GRANT_ENTRIES_PER_PAGE; 156 i < nframes_new * NR_GRANT_ENTRIES_PER_PAGE; 157 i++) { 158 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 159 gnt_entries[last_gnt_entry] = i; 160 last_gnt_entry++; 161 } 162 gnt_nr_grant_frames = nframes_new; 163 return 0; 164 } 165 166 static grant_ref_t 167 xengnt_get_entry() 168 { 169 grant_ref_t entry; 170 int s = splvm(); 171 static struct timeval xengnt_nonmemtime; 172 const static struct timeval xengnt_nonmemintvl = {5,0}; 173 174 if (last_gnt_entry == 0) { 175 if (xengnt_more_entries()) { 176 splx(s); 177 if (ratecheck(&xengnt_nonmemtime, &xengnt_nonmemintvl)) 178 printf("xengnt_get_entry: out of grant " 179 "table entries\n"); 180 return XENGNT_NO_ENTRY; 181 } 182 } 183 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 184 last_gnt_entry--; 185 entry = gnt_entries[last_gnt_entry]; 186 gnt_entries[last_gnt_entry] = XENGNT_NO_ENTRY; 187 splx(s); 188 KASSERT(entry != XENGNT_NO_ENTRY); 189 KASSERT(last_gnt_entry >= 0 && last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 190 return entry; 191 } 192 193 static void 194 xengnt_free_entry(grant_ref_t entry) 195 { 196 int s = splvm(); 197 KASSERT(gnt_entries[last_gnt_entry] == XENGNT_NO_ENTRY); 198 KASSERT(last_gnt_entry >= 0 && last_gnt_entry <= gnt_max_grant_frames * NR_GRANT_ENTRIES_PER_PAGE); 199 gnt_entries[last_gnt_entry] = entry; 200 last_gnt_entry++; 201 splx(s); 202 } 203 204 int 205 xengnt_grant_access(domid_t dom, paddr_t ma, int ro, grant_ref_t *entryp) 206 { 207 *entryp = xengnt_get_entry(); 208 if (__predict_false(*entryp == XENGNT_NO_ENTRY)) 209 return ENOMEM; 210 211 grant_table[*entryp].frame = ma >> PAGE_SHIFT; 212 grant_table[*entryp].domid = dom; 213 x86_lfence(); 214 grant_table[*entryp].flags = 215 GTF_permit_access | (ro ? GTF_readonly : 0); 216 return 0; 217 } 218 219 void 220 xengnt_revoke_access(grant_ref_t entry) 221 { 222 uint16_t flags, nflags; 223 224 nflags = grant_table[entry].flags; 225 226 do { 227 if ((flags = nflags) & (GTF_reading|GTF_writing)) 228 panic("xengnt_revoke_access: still in use"); 229 nflags = xen_atomic_cmpxchg16(&grant_table[entry].flags, 230 flags, 0); 231 } while (nflags != flags); 232 xengnt_free_entry(entry); 233 } 234 235 int 236 xengnt_grant_transfer(domid_t dom, grant_ref_t *entryp) 237 { 238 *entryp = xengnt_get_entry(); 239 if (__predict_false(*entryp == XENGNT_NO_ENTRY)) 240 return ENOMEM; 241 242 grant_table[*entryp].frame = 0; 243 grant_table[*entryp].domid =dom; 244 x86_lfence(); 245 grant_table[*entryp].flags = GTF_accept_transfer; 246 return 0; 247 } 248 249 paddr_t 250 xengnt_revoke_transfer(grant_ref_t entry) 251 { 252 paddr_t page; 253 uint16_t flags; 254 255 /* if the transfer has not started, free the entry and return 0 */ 256 while (!((flags = grant_table[entry].flags) & GTF_transfer_committed)) { 257 if (xen_atomic_cmpxchg16(&grant_table[entry].flags, 258 flags, 0) == flags ) { 259 xengnt_free_entry(entry); 260 return 0; 261 } 262 HYPERVISOR_yield(); 263 } 264 265 /* If transfer in progress, wait for completion */ 266 while (!((flags = grant_table[entry].flags) & GTF_transfer_completed)) 267 HYPERVISOR_yield(); 268 269 /* Read the frame number /after/ reading completion status. */ 270 __insn_barrier(); 271 page = grant_table[entry].frame; 272 if (page == 0) 273 printf("xengnt_revoke_transfer: guest sent pa 0\n"); 274 275 xengnt_free_entry(entry); 276 return page; 277 } 278 279 int 280 xengnt_status(grant_ref_t entry) 281 { 282 return (grant_table[entry].flags & (GTF_reading|GTF_writing)); 283 } 284