migration/multifd-zstd.c

   1 /*
   2  * Multifd zlib compression implementation
   3  *
   4  * Copyright (c) 2020 Red Hat Inc
   5  *
   6  * Authors:
   7  *  Juan Quintela <quintela@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include <zstd.h>
  15 #include "qemu/rcu.h"
  16 #include "exec/ramblock.h"
  17 #include "exec/target_page.h"
  18 #include "qapi/error.h"
  19 #include "migration.h"
  20 #include "trace.h"
  21 #include "multifd.h"
  22
  23 struct zstd_data {
  24     /* stream for compression */
  25     ZSTD_CStream *zcs;
  26     /* stream for decompression */
  27     ZSTD_DStream *zds;
  28     /* buffers */
  29     ZSTD_inBuffer in;
  30     ZSTD_outBuffer out;
  31     /* compressed buffer */
  32     uint8_t *zbuff;
  33     /* size of compressed buffer */
  34     uint32_t zbuff_len;
  35 };
  36
  37 /* Multifd zstd compression */
  38
  39 /**
  40  * zstd_send_setup: setup send side
  41  *
  42  * Setup each channel with zstd compression.
  43  *
  44  * Returns 0 for success or -1 for error
  45  *
  46  * @p: Params for the channel that we are using
  47  * @errp: pointer to an error
  48  */
  49 static int zstd_send_setup(MultiFDSendParams *p, Error **errp)
  50 {
  51     struct zstd_data *z = g_new0(struct zstd_data, 1);
  52     int res;
  53
  54     p->data = z;
  55     z->zcs = ZSTD_createCStream();
  56     if (!z->zcs) {
  57         g_free(z);
  58         error_setg(errp, "multifd %u: zstd createCStream failed", p->id);
  59         return -1;
  60     }
  61
  62     res = ZSTD_initCStream(z->zcs, migrate_multifd_zstd_level());
  63     if (ZSTD_isError(res)) {
  64         ZSTD_freeCStream(z->zcs);
  65         g_free(z);
  66         error_setg(errp, "multifd %u: initCStream failed with error %s",
  67                    p->id, ZSTD_getErrorName(res));
  68         return -1;
  69     }
  70     /* This is the maxium size of the compressed buffer */
  71     z->zbuff_len = ZSTD_compressBound(MULTIFD_PACKET_SIZE);
  72     z->zbuff = g_try_malloc(z->zbuff_len);
  73     if (!z->zbuff) {
  74         ZSTD_freeCStream(z->zcs);
  75         g_free(z);
  76         error_setg(errp, "multifd %u: out of memory for zbuff", p->id);
  77         return -1;
  78     }
  79     return 0;
  80 }
  81
  82 /**
  83  * zstd_send_cleanup: cleanup send side
  84  *
  85  * Close the channel and return memory.
  86  *
  87  * @p: Params for the channel that we are using
  88  * @errp: pointer to an error
  89  */
  90 static void zstd_send_cleanup(MultiFDSendParams *p, Error **errp)
  91 {
  92     struct zstd_data *z = p->data;
  93
  94     ZSTD_freeCStream(z->zcs);
  95     z->zcs = NULL;
  96     g_free(z->zbuff);
  97     z->zbuff = NULL;
  98     g_free(p->data);
  99     p->data = NULL;
 100 }
 101
 102 /**
 103  * zstd_send_prepare: prepare date to be able to send
 104  *
 105  * Create a compressed buffer with all the pages that we are going to
 106  * send.
 107  *
 108  * Returns 0 for success or -1 for error
 109  *
 110  * @p: Params for the channel that we are using
 111  * @errp: pointer to an error
 112  */
 113 static int zstd_send_prepare(MultiFDSendParams *p, Error **errp)
 114 {
 115     struct zstd_data *z = p->data;
 116     size_t page_size = qemu_target_page_size();
 117     int ret;
 118     uint32_t i;
 119
 120     z->out.dst = z->zbuff;
 121     z->out.size = z->zbuff_len;
 122     z->out.pos = 0;
 123
 124     for (i = 0; i < p->normal_num; i++) {
 125         ZSTD_EndDirective flush = ZSTD_e_continue;
 126
 127         if (i == p->normal_num - 1) {
 128             flush = ZSTD_e_flush;
 129         }
 130         z->in.src = p->pages->block->host + p->normal[i];
 131         z->in.size = page_size;
 132         z->in.pos = 0;
 133
 134         /*
 135          * Welcome to compressStream2 semantics
 136          *
 137          * We need to loop while:
 138          * - return is > 0
 139          * - there is input available
 140          * - there is output space free
 141          */
 142         do {
 143             ret = ZSTD_compressStream2(z->zcs, &z->out, &z->in, flush);
 144         } while (ret > 0 && (z->in.size - z->in.pos > 0)
 145                          && (z->out.size - z->out.pos > 0));
 146         if (ret > 0 && (z->in.size - z->in.pos > 0)) {
 147             error_setg(errp, "multifd %u: compressStream buffer too small",
 148                        p->id);
 149             return -1;
 150         }
 151         if (ZSTD_isError(ret)) {
 152             error_setg(errp, "multifd %u: compressStream error %s",
 153                        p->id, ZSTD_getErrorName(ret));
 154             return -1;
 155         }
 156     }
 157     p->iov[p->iovs_num].iov_base = z->zbuff;
 158     p->iov[p->iovs_num].iov_len = z->out.pos;
 159     p->iovs_num++;
 160     p->next_packet_size = z->out.pos;
 161     p->flags |= MULTIFD_FLAG_ZSTD;
 162
 163     return 0;
 164 }
 165
 166 /**
 167  * zstd_recv_setup: setup receive side
 168  *
 169  * Create the compressed channel and buffer.
 170  *
 171  * Returns 0 for success or -1 for error
 172  *
 173  * @p: Params for the channel that we are using
 174  * @errp: pointer to an error
 175  */
 176 static int zstd_recv_setup(MultiFDRecvParams *p, Error **errp)
 177 {
 178     struct zstd_data *z = g_new0(struct zstd_data, 1);
 179     int ret;
 180
 181     p->data = z;
 182     z->zds = ZSTD_createDStream();
 183     if (!z->zds) {
 184         g_free(z);
 185         error_setg(errp, "multifd %u: zstd createDStream failed", p->id);
 186         return -1;
 187     }
 188
 189     ret = ZSTD_initDStream(z->zds);
 190     if (ZSTD_isError(ret)) {
 191         ZSTD_freeDStream(z->zds);
 192         g_free(z);
 193         error_setg(errp, "multifd %u: initDStream failed with error %s",
 194                    p->id, ZSTD_getErrorName(ret));
 195         return -1;
 196     }
 197
 198     /* To be safe, we reserve twice the size of the packet */
 199     z->zbuff_len = MULTIFD_PACKET_SIZE * 2;
 200     z->zbuff = g_try_malloc(z->zbuff_len);
 201     if (!z->zbuff) {
 202         ZSTD_freeDStream(z->zds);
 203         g_free(z);
 204         error_setg(errp, "multifd %u: out of memory for zbuff", p->id);
 205         return -1;
 206     }
 207     return 0;
 208 }
 209
 210 /**
 211  * zstd_recv_cleanup: setup receive side
 212  *
 213  * For no compression this function does nothing.
 214  *
 215  * @p: Params for the channel that we are using
 216  */
 217 static void zstd_recv_cleanup(MultiFDRecvParams *p)
 218 {
 219     struct zstd_data *z = p->data;
 220
 221     ZSTD_freeDStream(z->zds);
 222     z->zds = NULL;
 223     g_free(z->zbuff);
 224     z->zbuff = NULL;
 225     g_free(p->data);
 226     p->data = NULL;
 227 }
 228
 229 /**
 230  * zstd_recv_pages: read the data from the channel into actual pages
 231  *
 232  * Read the compressed buffer, and uncompress it into the actual
 233  * pages.
 234  *
 235  * Returns 0 for success or -1 for error
 236  *
 237  * @p: Params for the channel that we are using
 238  * @errp: pointer to an error
 239  */
 240 static int zstd_recv_pages(MultiFDRecvParams *p, Error **errp)
 241 {
 242     uint32_t in_size = p->next_packet_size;
 243     uint32_t out_size = 0;
 244     size_t page_size = qemu_target_page_size();
 245     uint32_t expected_size = p->normal_num * page_size;
 246     uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
 247     struct zstd_data *z = p->data;
 248     int ret;
 249     int i;
 250
 251     if (flags != MULTIFD_FLAG_ZSTD) {
 252         error_setg(errp, "multifd %u: flags received %x flags expected %x",
 253                    p->id, flags, MULTIFD_FLAG_ZSTD);
 254         return -1;
 255     }
 256     ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp);
 257
 258     if (ret != 0) {
 259         return ret;
 260     }
 261
 262     z->in.src = z->zbuff;
 263     z->in.size = in_size;
 264     z->in.pos = 0;
 265
 266     for (i = 0; i < p->normal_num; i++) {
 267         z->out.dst = p->host + p->normal[i];
 268         z->out.size = page_size;
 269         z->out.pos = 0;
 270
 271         /*
 272          * Welcome to decompressStream semantics
 273          *
 274          * We need to loop while:
 275          * - return is > 0
 276          * - there is input available
 277          * - we haven't put out a full page
 278          */
 279         do {
 280             ret = ZSTD_decompressStream(z->zds, &z->out, &z->in);
 281         } while (ret > 0 && (z->in.size - z->in.pos > 0)
 282                          && (z->out.pos < page_size));
 283         if (ret > 0 && (z->out.pos < page_size)) {
 284             error_setg(errp, "multifd %u: decompressStream buffer too small",
 285                        p->id);
 286             return -1;
 287         }
 288         if (ZSTD_isError(ret)) {
 289             error_setg(errp, "multifd %u: decompressStream returned %s",
 290                        p->id, ZSTD_getErrorName(ret));
 291             return ret;
 292         }
 293         out_size += z->out.pos;
 294     }
 295     if (out_size != expected_size) {
 296         error_setg(errp, "multifd %u: packet size received %u size expected %u",
 297                    p->id, out_size, expected_size);
 298         return -1;
 299     }
 300     return 0;
 301 }
 302
 303 static MultiFDMethods multifd_zstd_ops = {
 304     .send_setup = zstd_send_setup,
 305     .send_cleanup = zstd_send_cleanup,
 306     .send_prepare = zstd_send_prepare,
 307     .recv_setup = zstd_recv_setup,
 308     .recv_cleanup = zstd_recv_cleanup,
 309     .recv_pages = zstd_recv_pages
 310 };
 311
 312 static void multifd_zstd_register(void)
 313 {
 314     multifd_register_ops(MULTIFD_COMPRESSION_ZSTD, &multifd_zstd_ops);
 315 }
 316
 317 migration_init(multifd_zstd_register);