| 1 | /* $NetBSD: balloon.c,v 1.17 2016/07/07 06:55:40 msaitoh Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2010 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software contributed to The NetBSD Foundation |
| 8 | * by Cherry G. Mathew <cherry@zyx.in> and |
| 9 | * Jean-Yves Migeon <jym@NetBSD.org> |
| 10 | * |
| 11 | * Redistribution and use in source and binary forms, with or without |
| 12 | * modification, are permitted provided that the following conditions |
| 13 | * are met: |
| 14 | * 1. Redistributions of source code must retain the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer. |
| 16 | * 2. Redistributions in binary form must reproduce the above copyright |
| 17 | * notice, this list of conditions and the following disclaimer in the |
| 18 | * documentation and/or other materials provided with the distribution. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 22 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 23 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 24 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 25 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 26 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 29 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 30 | * POSSIBILITY OF SUCH DAMAGE. |
| 31 | */ |
| 32 | |
| 33 | /* |
| 34 | * The Xen balloon driver enables growing and shrinking PV domains |
| 35 | * memory on the fly, by allocating and freeing memory pages directly. |
| 36 | * This management needs domain cooperation to work properly, especially |
| 37 | * during balloon_inflate() operation where a domain gives back memory to |
| 38 | * the hypervisor. |
| 39 | * |
| 40 | * Shrinking memory on a live system is a difficult task, and may render |
| 41 | * it unstable or lead to crash. The driver takes a conservative approach |
| 42 | * there by doing memory operations in smal steps of a few MiB each time. It |
| 43 | * will also refuse to decrease reservation below a certain threshold |
| 44 | * (XEN_RESERVATION_MIN), so as to avoid a complete kernel memory exhaustion. |
| 45 | * |
| 46 | * The user can intervene at two different levels to manage the ballooning |
| 47 | * of a domain: |
| 48 | * - directly within the domain using a sysctl(9) interface. |
| 49 | * - through the Xentools, by modifying the memory/target entry associated |
| 50 | * to a domain. This is usually done in dom0. |
| 51 | * |
| 52 | * Modification of the reservation is signaled by writing inside the |
| 53 | * memory/target node in Xenstore. Writing new values will fire the xenbus |
| 54 | * watcher, and wakeup the balloon thread to inflate or deflate balloon. |
| 55 | * |
| 56 | * Both sysctl(9) nodes and memory/target entry assume that the values passed |
| 57 | * to them are in KiB. Internally, the driver will convert this value in |
| 58 | * pages (assuming a page is PAGE_SIZE bytes), and issue the correct hypercalls |
| 59 | * to decrease/increase domain's reservation accordingly. |
| 60 | * |
| 61 | * XXX Pages used by balloon are tracked through entries stored in a SLIST. |
| 62 | * This allows driver to conveniently add/remove wired pages from memory |
| 63 | * without the need to support these "memory gaps" inside uvm(9). Still, the |
| 64 | * driver does not currently "plug" new pages into uvm(9) when more memory |
| 65 | * is available than originally managed by balloon. For example, deflating |
| 66 | * balloon with a total number of pages above physmem is not supported for |
| 67 | * now. See balloon_deflate() for more details. |
| 68 | * |
| 69 | */ |
| 70 | |
| 71 | #define BALLOONDEBUG 0 |
| 72 | |
| 73 | #include <sys/cdefs.h> |
| 74 | __KERNEL_RCSID(0, "$NetBSD: balloon.c,v 1.17 2016/07/07 06:55:40 msaitoh Exp $" ); |
| 75 | |
| 76 | #include <sys/inttypes.h> |
| 77 | #include <sys/device.h> |
| 78 | #include <sys/param.h> |
| 79 | |
| 80 | #include <sys/atomic.h> |
| 81 | #include <sys/condvar.h> |
| 82 | #include <sys/kernel.h> |
| 83 | #include <sys/kmem.h> |
| 84 | #include <sys/kthread.h> |
| 85 | #include <sys/mutex.h> |
| 86 | #include <sys/pool.h> |
| 87 | #include <sys/queue.h> |
| 88 | #include <sys/sysctl.h> |
| 89 | |
| 90 | #include <xen/xen.h> |
| 91 | #include <xen/xenbus.h> |
| 92 | #include <xen/balloon.h> |
| 93 | |
| 94 | #include <uvm/uvm.h> |
| 95 | #include <uvm/uvm.h> |
| 96 | #include <xen/xenpmap.h> |
| 97 | |
| 98 | #include "locators.h" |
| 99 | |
| 100 | /* |
| 101 | * Number of MFNs stored in the array passed back and forth between domain |
| 102 | * and balloon/hypervisor, during balloon_inflate() / balloon_deflate(). These |
| 103 | * should fit in a page, for performance reasons. |
| 104 | */ |
| 105 | #define BALLOON_DELTA (PAGE_SIZE / sizeof(xen_pfn_t)) |
| 106 | |
| 107 | /* |
| 108 | * Safeguard value. Refuse to go below this threshold, so that domain |
| 109 | * can keep some free pages for its own use. Value is arbitrary, and may |
| 110 | * evolve with time. |
| 111 | */ |
| 112 | #define BALLOON_BALLAST 256 /* In pages - 1MiB */ |
| 113 | #define XEN_RESERVATION_MIN (uvmexp.freemin + BALLOON_BALLAST) /* In pages */ |
| 114 | |
| 115 | /* KB <-> PAGEs */ |
| 116 | #define PAGE_SIZE_KB (PAGE_SIZE >> 10) /* page size in KB */ |
| 117 | #define BALLOON_PAGES_TO_KB(_pg) ((uint64_t)_pg * PAGE_SIZE_KB) |
| 118 | #define BALLOON_KB_TO_PAGES(_kb) (roundup(_kb, PAGE_SIZE_KB) / PAGE_SIZE_KB) |
| 119 | |
| 120 | /* |
| 121 | * A balloon page entry. Needed to track pages put/reclaimed from balloon |
| 122 | */ |
| 123 | struct balloon_page_entry { |
| 124 | struct vm_page *pg; |
| 125 | SLIST_ENTRY(balloon_page_entry) entry; |
| 126 | }; |
| 127 | |
| 128 | struct balloon_xenbus_softc { |
| 129 | device_t sc_dev; |
| 130 | struct sysctllog *sc_log; |
| 131 | |
| 132 | kmutex_t balloon_mtx; /* Protects condvar, target and res_min (below) */ |
| 133 | kcondvar_t balloon_cv; /* Condvar variable for target (below) */ |
| 134 | size_t balloon_target; /* Target domain reservation size in pages. */ |
| 135 | /* Minimum amount of memory reserved by domain, in KiB */ |
| 136 | uint64_t balloon_res_min; |
| 137 | |
| 138 | xen_pfn_t *sc_mfn_list; /* List of MFNs passed from/to balloon */ |
| 139 | pool_cache_t bpge_pool; /* pool cache for balloon page entries */ |
| 140 | /* linked list for tracking pages used by balloon */ |
| 141 | SLIST_HEAD(, balloon_page_entry) balloon_page_entries; |
| 142 | size_t balloon_num_page_entries; |
| 143 | }; |
| 144 | |
| 145 | static size_t xenmem_get_currentreservation(void); |
| 146 | static size_t xenmem_get_maxreservation(void); |
| 147 | |
| 148 | static int bpge_ctor(void *, void *, int); |
| 149 | static void bpge_dtor(void *, void *); |
| 150 | |
| 151 | static void balloon_thread(void *); |
| 152 | static size_t balloon_deflate(struct balloon_xenbus_softc*, size_t); |
| 153 | static size_t balloon_inflate(struct balloon_xenbus_softc*, size_t); |
| 154 | |
| 155 | static void sysctl_kern_xen_balloon_setup(struct balloon_xenbus_softc *); |
| 156 | static void balloon_xenbus_watcher(struct xenbus_watch *, const char **, |
| 157 | unsigned int); |
| 158 | |
| 159 | static int balloon_xenbus_match(device_t, cfdata_t, void *); |
| 160 | static void balloon_xenbus_attach(device_t, device_t, void *); |
| 161 | |
| 162 | CFATTACH_DECL_NEW(balloon, sizeof(struct balloon_xenbus_softc), |
| 163 | balloon_xenbus_match, balloon_xenbus_attach, NULL, NULL); |
| 164 | |
| 165 | static struct xenbus_watch balloon_xenbus_watch = { |
| 166 | .node = __UNCONST("memory/target" ), |
| 167 | .xbw_callback = balloon_xenbus_watcher, |
| 168 | }; |
| 169 | |
| 170 | static struct balloon_xenbus_softc *balloon_sc; |
| 171 | |
| 172 | static int |
| 173 | balloon_xenbus_match(device_t parent, cfdata_t match, void *aux) |
| 174 | { |
| 175 | struct xenbusdev_attach_args *xa = aux; |
| 176 | |
| 177 | if (strcmp(xa->xa_type, "balloon" ) != 0) |
| 178 | return 0; |
| 179 | |
| 180 | if (match->cf_loc[XENBUSCF_ID] != XENBUSCF_ID_DEFAULT && |
| 181 | match->cf_loc[XENBUSCF_ID] != xa->xa_id) |
| 182 | return 0; |
| 183 | |
| 184 | return 1; |
| 185 | } |
| 186 | |
| 187 | static void |
| 188 | balloon_xenbus_attach(device_t parent, device_t self, void *aux) |
| 189 | { |
| 190 | xen_pfn_t *mfn_list; |
| 191 | size_t currentpages; |
| 192 | struct balloon_xenbus_softc *sc = balloon_sc = device_private(self); |
| 193 | |
| 194 | aprint_normal(": Xen Balloon driver\n" ); |
| 195 | sc->sc_dev = self; |
| 196 | |
| 197 | /* Initialize target mutex and condvar */ |
| 198 | mutex_init(&sc->balloon_mtx, MUTEX_DEFAULT, IPL_NONE); |
| 199 | cv_init(&sc->balloon_cv, "xen_balloon" ); |
| 200 | |
| 201 | SLIST_INIT(&sc->balloon_page_entries); |
| 202 | sc->balloon_num_page_entries = 0; |
| 203 | |
| 204 | /* Get current number of pages */ |
| 205 | currentpages = xenmem_get_currentreservation(); |
| 206 | |
| 207 | KASSERT(currentpages > 0); |
| 208 | |
| 209 | /* Update initial target value - no need to lock for initialization */ |
| 210 | sc->balloon_target = currentpages; |
| 211 | |
| 212 | /* Set the values used by sysctl */ |
| 213 | sc->balloon_res_min = |
| 214 | BALLOON_PAGES_TO_KB(XEN_RESERVATION_MIN); |
| 215 | |
| 216 | aprint_normal_dev(self, "current reservation: %" PRIu64" KiB\n" , |
| 217 | BALLOON_PAGES_TO_KB(currentpages)); |
| 218 | #if BALLOONDEBUG |
| 219 | aprint_normal_dev(self, "min reservation: %" PRIu64" KiB\n" , |
| 220 | sc->balloon_res_min); |
| 221 | aprint_normal_dev(self, "max reservation: %" PRIu64" KiB\n" , |
| 222 | BALLOON_PAGES_TO_KB(xenmem_get_maxreservation())); |
| 223 | #endif |
| 224 | |
| 225 | sc->bpge_pool = pool_cache_init(sizeof(struct balloon_page_entry), |
| 226 | 0, 0, 0, "xen_bpge" , NULL, IPL_NONE, bpge_ctor, bpge_dtor, NULL); |
| 227 | |
| 228 | sysctl_kern_xen_balloon_setup(sc); |
| 229 | |
| 230 | /* List of MFNs passed from/to balloon for inflating/deflating */ |
| 231 | mfn_list = kmem_alloc(BALLOON_DELTA * sizeof(*mfn_list), KM_SLEEP); |
| 232 | sc->sc_mfn_list = mfn_list; |
| 233 | |
| 234 | /* Setup xenbus node watch callback */ |
| 235 | if (register_xenbus_watch(&balloon_xenbus_watch)) { |
| 236 | aprint_error_dev(self, "unable to watch memory/target\n" ); |
| 237 | goto error; |
| 238 | } |
| 239 | |
| 240 | /* Setup kernel thread to asynchronously (in/de)-flate the balloon */ |
| 241 | if (kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL, balloon_thread, |
| 242 | sc, NULL, "xen_balloon" )) { |
| 243 | aprint_error_dev(self, "unable to create balloon thread\n" ); |
| 244 | unregister_xenbus_watch(&balloon_xenbus_watch); |
| 245 | goto error; |
| 246 | } |
| 247 | |
| 248 | if (!pmf_device_register(self, NULL, NULL)) |
| 249 | aprint_error_dev(self, "couldn't establish power handler\n" ); |
| 250 | |
| 251 | return; |
| 252 | |
| 253 | error: |
| 254 | sysctl_teardown(&sc->sc_log); |
| 255 | cv_destroy(&sc->balloon_cv); |
| 256 | mutex_destroy(&sc->balloon_mtx); |
| 257 | return; |
| 258 | |
| 259 | } |
| 260 | |
| 261 | /* |
| 262 | * Returns maximum memory reservation available to current domain. In Xen |
| 263 | * with DOMID_SELF, this hypercall never fails: return value should be |
| 264 | * interpreted as unsigned. |
| 265 | * |
| 266 | */ |
| 267 | static size_t |
| 268 | xenmem_get_maxreservation(void) |
| 269 | { |
| 270 | int s; |
| 271 | unsigned int ret; |
| 272 | |
| 273 | s = splvm(); |
| 274 | ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, |
| 275 | & (domid_t) { DOMID_SELF }); |
| 276 | |
| 277 | splx(s); |
| 278 | |
| 279 | if (ret == 0) { |
| 280 | /* well, a maximum reservation of 0 is really bogus */ |
| 281 | panic("%s failed, maximum reservation returned 0" , __func__); |
| 282 | } |
| 283 | |
| 284 | return ret; |
| 285 | } |
| 286 | |
| 287 | /* Returns current reservation, in pages */ |
| 288 | static size_t |
| 289 | xenmem_get_currentreservation(void) |
| 290 | { |
| 291 | int s, ret; |
| 292 | |
| 293 | s = splvm(); |
| 294 | ret = HYPERVISOR_memory_op(XENMEM_current_reservation, |
| 295 | & (domid_t) { DOMID_SELF }); |
| 296 | splx(s); |
| 297 | |
| 298 | if (ret < 0) { |
| 299 | panic("%s failed: %d" , __func__, ret); |
| 300 | } |
| 301 | |
| 302 | return ret; |
| 303 | } |
| 304 | |
| 305 | /* |
| 306 | * Get value (in KiB) of memory/target in XenStore for current domain |
| 307 | * A return value of 0 can be considered as bogus or absent. |
| 308 | */ |
| 309 | static unsigned long long |
| 310 | balloon_xenbus_read_target(void) |
| 311 | { |
| 312 | unsigned long long new_target; |
| 313 | int err = xenbus_read_ull(NULL, "memory" , "target" , &new_target, 0); |
| 314 | |
| 315 | switch(err) { |
| 316 | case 0: |
| 317 | return new_target; |
| 318 | case ENOENT: |
| 319 | break; |
| 320 | default: |
| 321 | device_printf(balloon_sc->sc_dev, |
| 322 | "error %d, couldn't read xenbus target node\n" , err); |
| 323 | break; |
| 324 | } |
| 325 | |
| 326 | return 0; |
| 327 | } |
| 328 | |
| 329 | /* Set memory/target value (in KiB) in XenStore for current domain */ |
| 330 | static void |
| 331 | balloon_xenbus_write_target(unsigned long long new_target) |
| 332 | { |
| 333 | int err = xenbus_printf(NULL, "memory" , "target" , "%llu" , new_target); |
| 334 | |
| 335 | if (err != 0) { |
| 336 | device_printf(balloon_sc->sc_dev, |
| 337 | "error %d, couldn't write xenbus target node\n" , err); |
| 338 | } |
| 339 | |
| 340 | return; |
| 341 | } |
| 342 | |
| 343 | static int |
| 344 | bpge_ctor(void *arg, void *obj, int flags) |
| 345 | { |
| 346 | struct balloon_page_entry *bpge = obj; |
| 347 | |
| 348 | bpge->pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_ZERO); |
| 349 | if (bpge->pg == NULL) |
| 350 | return ENOMEM; |
| 351 | |
| 352 | return 0; |
| 353 | |
| 354 | } |
| 355 | |
| 356 | static void |
| 357 | bpge_dtor(void *arg, void *obj) |
| 358 | { |
| 359 | struct balloon_page_entry *bpge = obj; |
| 360 | |
| 361 | uvm_pagefree(bpge->pg); |
| 362 | } |
| 363 | |
| 364 | /* |
| 365 | * Inflate balloon. Pages are moved out of domain's memory towards balloon. |
| 366 | */ |
| 367 | static size_t |
| 368 | balloon_inflate(struct balloon_xenbus_softc *sc, size_t tpages) |
| 369 | { |
| 370 | int rpages, s, ret; |
| 371 | paddr_t pa; |
| 372 | struct balloon_page_entry *bpg_entry; |
| 373 | xen_pfn_t *mfn_list = sc->sc_mfn_list; |
| 374 | |
| 375 | struct xen_memory_reservation reservation = { |
| 376 | .address_bits = 0, |
| 377 | .extent_order = 0, |
| 378 | .domid = DOMID_SELF |
| 379 | }; |
| 380 | |
| 381 | KASSERT(tpages > 0); |
| 382 | KASSERT(tpages <= BALLOON_DELTA); |
| 383 | |
| 384 | memset(mfn_list, 0, BALLOON_DELTA * sizeof(*mfn_list)); |
| 385 | |
| 386 | /* allocate pages that will be given to Hypervisor */ |
| 387 | for (rpages = 0; rpages < tpages; rpages++) { |
| 388 | |
| 389 | bpg_entry = pool_cache_get(sc->bpge_pool, PR_WAITOK); |
| 390 | if (bpg_entry == NULL) { |
| 391 | /* failed reserving a page for balloon */ |
| 392 | break; |
| 393 | } |
| 394 | |
| 395 | pa = VM_PAGE_TO_PHYS(bpg_entry->pg); |
| 396 | |
| 397 | mfn_list[rpages] = xpmap_ptom(pa) >> PAGE_SHIFT; |
| 398 | |
| 399 | s = splvm(); |
| 400 | /* Invalidate pg */ |
| 401 | xpmap_ptom_unmap(pa); |
| 402 | splx(s); |
| 403 | |
| 404 | SLIST_INSERT_HEAD(&balloon_sc->balloon_page_entries, |
| 405 | bpg_entry, entry); |
| 406 | balloon_sc->balloon_num_page_entries++; |
| 407 | } |
| 408 | |
| 409 | /* Hand over pages to Hypervisor */ |
| 410 | set_xen_guest_handle(reservation.extent_start, mfn_list); |
| 411 | reservation.nr_extents = rpages; |
| 412 | |
| 413 | s = splvm(); |
| 414 | ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, |
| 415 | &reservation); |
| 416 | splx(s); |
| 417 | |
| 418 | if (ret != rpages) { |
| 419 | /* |
| 420 | * we are in bad shape: the operation failed for certain |
| 421 | * MFNs. As the API does not allow us to know which frame |
| 422 | * numbers were erroneous, we cannot really recover safely. |
| 423 | */ |
| 424 | panic("%s: decrease reservation failed: was %d, " |
| 425 | "returned %d" , device_xname(sc->sc_dev), rpages, ret); |
| 426 | } |
| 427 | |
| 428 | #if BALLOONDEBUG |
| 429 | device_printf(sc->sc_dev, "inflate %zu => inflated by %d\n" , |
| 430 | tpages, rpages); |
| 431 | #endif |
| 432 | return rpages; |
| 433 | } |
| 434 | |
| 435 | /* |
| 436 | * Deflate balloon. Pages are given back to domain's memory. |
| 437 | */ |
| 438 | static size_t |
| 439 | balloon_deflate(struct balloon_xenbus_softc *sc, size_t tpages) |
| 440 | { |
| 441 | int rpages, s, ret; |
| 442 | paddr_t pa; |
| 443 | struct balloon_page_entry *bpg_entry; |
| 444 | xen_pfn_t *mfn_list = sc->sc_mfn_list; |
| 445 | |
| 446 | struct xen_memory_reservation reservation = { |
| 447 | .address_bits = 0, |
| 448 | .extent_order = 0, |
| 449 | .domid = DOMID_SELF |
| 450 | }; |
| 451 | |
| 452 | KASSERT(tpages > 0); |
| 453 | KASSERT(tpages <= BALLOON_DELTA); |
| 454 | |
| 455 | memset(mfn_list, 0, BALLOON_DELTA * sizeof(*mfn_list)); |
| 456 | |
| 457 | /* |
| 458 | * If the list is empty, we are deflating balloon beyond empty. This |
| 459 | * is currently unsupported as this would require to dynamically add |
| 460 | * new memory pages inside uvm(9) and instruct pmap(9) on how to |
| 461 | * handle them. For now, we clip reservation up to the point we |
| 462 | * can manage them, eg. the remaining bpg entries in the SLIST. |
| 463 | * XXX find a way to hotplug memory through uvm(9)/pmap(9). |
| 464 | */ |
| 465 | if (tpages > sc->balloon_num_page_entries) { |
| 466 | device_printf(sc->sc_dev, |
| 467 | "memory 'hot-plug' unsupported - clipping " |
| 468 | "reservation %zu => %zu pages.\n" , |
| 469 | tpages, sc->balloon_num_page_entries); |
| 470 | tpages = sc->balloon_num_page_entries; |
| 471 | } |
| 472 | |
| 473 | /* reclaim pages from balloon */ |
| 474 | set_xen_guest_handle(reservation.extent_start, mfn_list); |
| 475 | reservation.nr_extents = tpages; |
| 476 | |
| 477 | s = splvm(); |
| 478 | ret = HYPERVISOR_memory_op(XENMEM_increase_reservation, &reservation); |
| 479 | splx(s); |
| 480 | |
| 481 | if (ret < 0) { |
| 482 | panic("%s: increase reservation failed, ret %d" , |
| 483 | device_xname(sc->sc_dev), ret); |
| 484 | } |
| 485 | |
| 486 | if (ret != tpages) { |
| 487 | device_printf(sc->sc_dev, |
| 488 | "increase reservation incomplete: was %zu, " |
| 489 | "returned %d\n" , tpages, ret); |
| 490 | } |
| 491 | |
| 492 | /* plug pages back into memory through bpge entries */ |
| 493 | for (rpages = 0; rpages < ret; rpages++) { |
| 494 | |
| 495 | #ifdef noyet |
| 496 | if (sc->balloon_num_page_entries == 0) { |
| 497 | /* |
| 498 | * XXX This is the case where extra "hot-plug" |
| 499 | * mem w.r.t boot comes in |
| 500 | */ |
| 501 | device_printf(sc->sc_dev, |
| 502 | "List empty. Cannot be collapsed further!\n" ); |
| 503 | break; |
| 504 | } |
| 505 | #endif |
| 506 | |
| 507 | bpg_entry = SLIST_FIRST(&balloon_sc->balloon_page_entries); |
| 508 | SLIST_REMOVE_HEAD(&balloon_sc->balloon_page_entries, entry); |
| 509 | balloon_sc->balloon_num_page_entries--; |
| 510 | |
| 511 | /* Update P->M */ |
| 512 | pa = VM_PAGE_TO_PHYS(bpg_entry->pg); |
| 513 | |
| 514 | s = splvm(); |
| 515 | |
| 516 | xpmap_ptom_map(pa, ptoa(mfn_list[rpages])); |
| 517 | xpq_queue_machphys_update(ptoa(mfn_list[rpages]), pa); |
| 518 | |
| 519 | splx(s); |
| 520 | |
| 521 | pool_cache_put(sc->bpge_pool, bpg_entry); |
| 522 | } |
| 523 | |
| 524 | xpq_flush_queue(); |
| 525 | |
| 526 | #if BALLOONDEBUG |
| 527 | device_printf(sc->sc_dev, "deflate %zu => deflated by %d\n" , |
| 528 | tpages, rpages); |
| 529 | #endif |
| 530 | return rpages; |
| 531 | } |
| 532 | |
| 533 | /* |
| 534 | * The balloon thread is responsible for handling inflate/deflate balloon |
| 535 | * requests for the current domain given the new "target" value. |
| 536 | */ |
| 537 | static void |
| 538 | balloon_thread(void *cookie) |
| 539 | { |
| 540 | int ret; |
| 541 | size_t current, diff, target; |
| 542 | struct balloon_xenbus_softc *sc = cookie; |
| 543 | |
| 544 | for/*ever*/ (;;) { |
| 545 | current = xenmem_get_currentreservation(); |
| 546 | |
| 547 | /* |
| 548 | * We assume that balloon_xenbus_watcher() and |
| 549 | * sysctl(9) handlers checked the sanity of the |
| 550 | * new target value. |
| 551 | */ |
| 552 | mutex_enter(&sc->balloon_mtx); |
| 553 | target = sc->balloon_target; |
| 554 | if (current != target) { |
| 555 | /* |
| 556 | * There is work to do. Inflate/deflate in |
| 557 | * increments of BALLOON_DELTA pages at maximum. The |
| 558 | * risk of integer wrapping is mitigated by |
| 559 | * BALLOON_DELTA, which is the upper bound. |
| 560 | */ |
| 561 | mutex_exit(&sc->balloon_mtx); |
| 562 | diff = MIN(target - current, BALLOON_DELTA); |
| 563 | if (current < target) |
| 564 | ret = balloon_deflate(sc, diff); |
| 565 | else |
| 566 | ret = balloon_inflate(sc, diff); |
| 567 | |
| 568 | if (ret != diff) { |
| 569 | /* |
| 570 | * Something went wrong during operation. |
| 571 | * Log error then feedback current value in |
| 572 | * target so that thread gets back to waiting |
| 573 | * for the next iteration |
| 574 | */ |
| 575 | device_printf(sc->sc_dev, |
| 576 | "WARNING: balloon could not reach target " |
| 577 | "%zu (current %zu)\n" , |
| 578 | target, current); |
| 579 | current = xenmem_get_currentreservation(); |
| 580 | mutex_enter(&sc->balloon_mtx); |
| 581 | sc->balloon_target = current; |
| 582 | mutex_exit(&sc->balloon_mtx); |
| 583 | } |
| 584 | } else { |
| 585 | /* no need for change -- wait for a signal */ |
| 586 | cv_wait(&sc->balloon_cv, &sc->balloon_mtx); |
| 587 | mutex_exit(&sc->balloon_mtx); |
| 588 | } |
| 589 | } |
| 590 | } |
| 591 | |
| 592 | /* |
| 593 | * Handler called when memory/target value changes inside Xenstore. |
| 594 | * All sanity checks must also happen in this handler, as it is the common |
| 595 | * entry point where controller domain schedules balloon operations. |
| 596 | */ |
| 597 | static void |
| 598 | balloon_xenbus_watcher(struct xenbus_watch *watch, const char **vec, |
| 599 | unsigned int len) |
| 600 | { |
| 601 | size_t new_target; |
| 602 | uint64_t target_kb, target_max, target_min; |
| 603 | |
| 604 | target_kb = balloon_xenbus_read_target(); |
| 605 | if (target_kb == 0) { |
| 606 | /* bogus -- just return */ |
| 607 | return; |
| 608 | } |
| 609 | |
| 610 | mutex_enter(&balloon_sc->balloon_mtx); |
| 611 | target_min = balloon_sc->balloon_res_min; |
| 612 | mutex_exit(&balloon_sc->balloon_mtx); |
| 613 | if (target_kb < target_min) { |
| 614 | device_printf(balloon_sc->sc_dev, |
| 615 | "new target %" PRIu64" is below min %" PRIu64"\n" , |
| 616 | target_kb, target_min); |
| 617 | return; |
| 618 | } |
| 619 | |
| 620 | target_max = BALLOON_PAGES_TO_KB(xenmem_get_maxreservation()); |
| 621 | if (target_kb > target_max) { |
| 622 | /* |
| 623 | * Should not happen. Hypervisor should block balloon |
| 624 | * requests above mem-max. |
| 625 | */ |
| 626 | device_printf(balloon_sc->sc_dev, |
| 627 | "new target %" PRIu64" is above max %" PRIu64"\n" , |
| 628 | target_kb, target_max); |
| 629 | return; |
| 630 | } |
| 631 | |
| 632 | new_target = BALLOON_KB_TO_PAGES(target_kb); |
| 633 | |
| 634 | device_printf(balloon_sc->sc_dev, |
| 635 | "current reservation: %zu pages => target: %zu pages\n" , |
| 636 | xenmem_get_currentreservation(), new_target); |
| 637 | |
| 638 | /* Only update target if its value changes */ |
| 639 | mutex_enter(&balloon_sc->balloon_mtx); |
| 640 | if (balloon_sc->balloon_target != new_target) { |
| 641 | balloon_sc->balloon_target = new_target; |
| 642 | cv_signal(&balloon_sc->balloon_cv); |
| 643 | } |
| 644 | mutex_exit(&balloon_sc->balloon_mtx); |
| 645 | |
| 646 | return; |
| 647 | } |
| 648 | |
| 649 | /* |
| 650 | * sysctl(9) stuff |
| 651 | */ |
| 652 | |
| 653 | /* routine to control the minimum memory reserved for the domain */ |
| 654 | static int |
| 655 | sysctl_kern_xen_balloon_min(SYSCTLFN_ARGS) |
| 656 | { |
| 657 | struct sysctlnode node; |
| 658 | u_quad_t newval; |
| 659 | int error; |
| 660 | |
| 661 | node = *rnode; |
| 662 | node.sysctl_data = &newval; |
| 663 | |
| 664 | mutex_enter(&balloon_sc->balloon_mtx); |
| 665 | newval = balloon_sc->balloon_res_min; |
| 666 | mutex_exit(&balloon_sc->balloon_mtx); |
| 667 | |
| 668 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 669 | if (error || newp == NULL) |
| 670 | return error; |
| 671 | |
| 672 | /* Safeguard value: refuse to go below. */ |
| 673 | if (newval < XEN_RESERVATION_MIN) { |
| 674 | device_printf(balloon_sc->sc_dev, |
| 675 | "cannot set min below minimum safe value (%d)\n" , |
| 676 | XEN_RESERVATION_MIN); |
| 677 | return EPERM; |
| 678 | } |
| 679 | |
| 680 | mutex_enter(&balloon_sc->balloon_mtx); |
| 681 | if (balloon_sc->balloon_res_min != newval) |
| 682 | balloon_sc->balloon_res_min = newval; |
| 683 | mutex_exit(&balloon_sc->balloon_mtx); |
| 684 | |
| 685 | return 0; |
| 686 | } |
| 687 | |
| 688 | /* Returns the maximum memory reservation of the domain */ |
| 689 | static int |
| 690 | sysctl_kern_xen_balloon_max(SYSCTLFN_ARGS) |
| 691 | { |
| 692 | struct sysctlnode node; |
| 693 | u_quad_t node_val; |
| 694 | |
| 695 | node = *rnode; |
| 696 | |
| 697 | node_val = BALLOON_PAGES_TO_KB(xenmem_get_maxreservation()); |
| 698 | node.sysctl_data = &node_val; |
| 699 | return sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 700 | } |
| 701 | |
| 702 | /* Returns the current memory reservation of the domain */ |
| 703 | static int |
| 704 | sysctl_kern_xen_balloon_current(SYSCTLFN_ARGS) |
| 705 | { |
| 706 | struct sysctlnode node; |
| 707 | u_quad_t node_val; |
| 708 | |
| 709 | node = *rnode; |
| 710 | |
| 711 | node_val = BALLOON_PAGES_TO_KB(xenmem_get_currentreservation()); |
| 712 | node.sysctl_data = &node_val; |
| 713 | return sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 714 | } |
| 715 | |
| 716 | /* |
| 717 | * Returns the target memory reservation of the domain |
| 718 | * When reading, this sysctl will return the value of the balloon_target |
| 719 | * variable, converted into KiB |
| 720 | * When used for writing, it will update the new memory/target value |
| 721 | * in XenStore, but will not update the balloon_target variable directly. |
| 722 | * This will be done by the Xenbus watch handler, balloon_xenbus_watcher(). |
| 723 | */ |
| 724 | static int |
| 725 | sysctl_kern_xen_balloon_target(SYSCTLFN_ARGS) |
| 726 | { |
| 727 | struct sysctlnode node; |
| 728 | u_quad_t newval, res_min, res_max; |
| 729 | int error; |
| 730 | |
| 731 | node = *rnode; |
| 732 | node.sysctl_data = &newval; |
| 733 | |
| 734 | mutex_enter(&balloon_sc->balloon_mtx); |
| 735 | newval = BALLOON_PAGES_TO_KB(balloon_sc->balloon_target); |
| 736 | res_min = balloon_sc->balloon_res_min; |
| 737 | mutex_exit(&balloon_sc->balloon_mtx); |
| 738 | |
| 739 | error = sysctl_lookup(SYSCTLFN_CALL(&node)); |
| 740 | if (newp == NULL || error != 0) { |
| 741 | return error; |
| 742 | } |
| 743 | |
| 744 | /* |
| 745 | * Sanity check new size |
| 746 | * We should not balloon below the minimum reservation |
| 747 | * set by the domain, nor above the maximum reservation set |
| 748 | * by domain controller. |
| 749 | * Note: domain is not supposed to receive balloon requests when |
| 750 | * they are above maximum reservation, but better be safe than |
| 751 | * sorry. |
| 752 | */ |
| 753 | res_max = BALLOON_PAGES_TO_KB(xenmem_get_maxreservation()); |
| 754 | if (newval < res_min || newval > res_max) { |
| 755 | #if BALLOONDEBUG |
| 756 | device_printf(balloon_sc->sc_dev, |
| 757 | "new value out of bounds: %" PRIu64"\n" , newval); |
| 758 | device_printf(balloon_sc->sc_dev, |
| 759 | "min %" PRIu64", max %" PRIu64"\n" , res_min, res_max); |
| 760 | #endif |
| 761 | return EPERM; |
| 762 | } |
| 763 | |
| 764 | /* |
| 765 | * Write new value inside Xenstore. This will fire the memory/target |
| 766 | * watch handler, balloon_xenbus_watcher(). |
| 767 | */ |
| 768 | balloon_xenbus_write_target(newval); |
| 769 | |
| 770 | return 0; |
| 771 | } |
| 772 | |
| 773 | /* sysctl(9) nodes creation */ |
| 774 | static void |
| 775 | sysctl_kern_xen_balloon_setup(struct balloon_xenbus_softc *sc) |
| 776 | { |
| 777 | const struct sysctlnode *node = NULL; |
| 778 | struct sysctllog **clog = &sc->sc_log; |
| 779 | |
| 780 | sysctl_createv(clog, 0, NULL, &node, |
| 781 | CTLFLAG_PERMANENT, |
| 782 | CTLTYPE_NODE, "machdep" , NULL, |
| 783 | NULL, 0, NULL, 0, |
| 784 | CTL_MACHDEP, CTL_EOL); |
| 785 | |
| 786 | sysctl_createv(clog, 0, &node, &node, |
| 787 | CTLFLAG_PERMANENT, |
| 788 | CTLTYPE_NODE, "xen" , |
| 789 | SYSCTL_DESCR("Xen top level node" ), |
| 790 | NULL, 0, NULL, 0, |
| 791 | CTL_CREATE, CTL_EOL); |
| 792 | |
| 793 | sysctl_createv(clog, 0, &node, &node, |
| 794 | CTLFLAG_PERMANENT, |
| 795 | CTLTYPE_NODE, "balloon" , |
| 796 | SYSCTL_DESCR("Balloon details" ), |
| 797 | NULL, 0, NULL, 0, |
| 798 | CTL_CREATE, CTL_EOL); |
| 799 | |
| 800 | sysctl_createv(clog, 0, &node, NULL, |
| 801 | CTLFLAG_PERMANENT | CTLFLAG_READONLY, |
| 802 | CTLTYPE_QUAD, "current" , |
| 803 | SYSCTL_DESCR("Domain's current memory reservation from " |
| 804 | "hypervisor, in KiB." ), |
| 805 | sysctl_kern_xen_balloon_current, 0, NULL, 0, |
| 806 | CTL_CREATE, CTL_EOL); |
| 807 | |
| 808 | sysctl_createv(clog, 0, &node, NULL, |
| 809 | CTLFLAG_PERMANENT | CTLFLAG_READWRITE, |
| 810 | CTLTYPE_QUAD, "target" , |
| 811 | SYSCTL_DESCR("Target memory reservation for domain, in KiB." ), |
| 812 | sysctl_kern_xen_balloon_target, 0, NULL, 0, |
| 813 | CTL_CREATE, CTL_EOL); |
| 814 | |
| 815 | sysctl_createv(clog, 0, &node, NULL, |
| 816 | CTLFLAG_PERMANENT | CTLFLAG_READWRITE, |
| 817 | CTLTYPE_QUAD, "min" , |
| 818 | SYSCTL_DESCR("Minimum amount of memory the domain " |
| 819 | "reserves, in KiB." ), |
| 820 | sysctl_kern_xen_balloon_min, 0, NULL, 0, |
| 821 | CTL_CREATE, CTL_EOL); |
| 822 | |
| 823 | sysctl_createv(clog, 0, &node, NULL, |
| 824 | CTLFLAG_PERMANENT | CTLFLAG_READONLY, |
| 825 | CTLTYPE_QUAD, "max" , |
| 826 | SYSCTL_DESCR("Maximum amount of memory the domain " |
| 827 | "can use, in KiB." ), |
| 828 | sysctl_kern_xen_balloon_max, 0, NULL, 0, |
| 829 | CTL_CREATE, CTL_EOL); |
| 830 | } |
| 831 | |