migration/multifd-zlib.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 <zlib.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 "options.h"
  22 #include "multifd.h"
  23
  24 struct zlib_data {
  25     /* stream for compression */
  26     z_stream zs;
  27     /* compressed buffer */
  28     uint8_t *zbuff;
  29     /* size of compressed buffer */
  30     uint32_t zbuff_len;
  31     /* uncompressed buffer of size qemu_target_page_size() */
  32     uint8_t *buf;
  33 };
  34
  35 /* Multifd zlib compression */
  36
  37 /**
  38  * zlib_send_setup: setup send side
  39  *
  40  * Setup each channel with zlib compression.
  41  *
  42  * Returns 0 for success or -1 for error
  43  *
  44  * @p: Params for the channel that we are using
  45  * @errp: pointer to an error
  46  */
  47 static int zlib_send_setup(MultiFDSendParams *p, Error **errp)
  48 {
  49     struct zlib_data *z = g_new0(struct zlib_data, 1);
  50     z_stream *zs = &z->zs;
  51     const char *err_msg;
  52
  53     zs->zalloc = Z_NULL;
  54     zs->zfree = Z_NULL;
  55     zs->opaque = Z_NULL;
  56     if (deflateInit(zs, migrate_multifd_zlib_level()) != Z_OK) {
  57         err_msg = "deflate init failed";
  58         goto err_free_z;
  59     }
  60     /* This is the maximum size of the compressed buffer */
  61     z->zbuff_len = compressBound(MULTIFD_PACKET_SIZE);
  62     z->zbuff = g_try_malloc(z->zbuff_len);
  63     if (!z->zbuff) {
  64         err_msg = "out of memory for zbuff";
  65         goto err_deflate_end;
  66     }
  67     z->buf = g_try_malloc(qemu_target_page_size());
  68     if (!z->buf) {
  69         err_msg = "out of memory for buf";
  70         goto err_free_zbuff;
  71     }
  72     p->data = z;
  73     return 0;
  74
  75 err_free_zbuff:
  76     g_free(z->zbuff);
  77 err_deflate_end:
  78     deflateEnd(&z->zs);
  79 err_free_z:
  80     g_free(z);
  81     error_setg(errp, "multifd %u: %s", p->id, err_msg);
  82     return -1;
  83 }
  84
  85 /**
  86  * zlib_send_cleanup: cleanup send side
  87  *
  88  * Close the channel and return memory.
  89  *
  90  * @p: Params for the channel that we are using
  91  * @errp: pointer to an error
  92  */
  93 static void zlib_send_cleanup(MultiFDSendParams *p, Error **errp)
  94 {
  95     struct zlib_data *z = p->data;
  96
  97     deflateEnd(&z->zs);
  98     g_free(z->zbuff);
  99     z->zbuff = NULL;
 100     g_free(z->buf);
 101     z->buf = NULL;
 102     g_free(p->data);
 103     p->data = NULL;
 104 }
 105
 106 /**
 107  * zlib_send_prepare: prepare date to be able to send
 108  *
 109  * Create a compressed buffer with all the pages that we are going to
 110  * send.
 111  *
 112  * Returns 0 for success or -1 for error
 113  *
 114  * @p: Params for the channel that we are using
 115  * @errp: pointer to an error
 116  */
 117 static int zlib_send_prepare(MultiFDSendParams *p, Error **errp)
 118 {
 119     struct zlib_data *z = p->data;
 120     z_stream *zs = &z->zs;
 121     uint32_t out_size = 0;
 122     int ret;
 123     uint32_t i;
 124
 125     for (i = 0; i < p->normal_num; i++) {
 126         uint32_t available = z->zbuff_len - out_size;
 127         int flush = Z_NO_FLUSH;
 128
 129         if (i == p->normal_num - 1) {
 130             flush = Z_SYNC_FLUSH;
 131         }
 132
 133         /*
 134          * Since the VM might be running, the page may be changing concurrently
 135          * with compression. zlib does not guarantee that this is safe,
 136          * therefore copy the page before calling deflate().
 137          */
 138         memcpy(z->buf, p->pages->block->host + p->normal[i], p->page_size);
 139         zs->avail_in = p->page_size;
 140         zs->next_in = z->buf;
 141
 142         zs->avail_out = available;
 143         zs->next_out = z->zbuff + out_size;
 144
 145         /*
 146          * Welcome to deflate semantics
 147          *
 148          * We need to loop while:
 149          * - return is Z_OK
 150          * - there are stuff to be compressed
 151          * - there are output space free
 152          */
 153         do {
 154             ret = deflate(zs, flush);
 155         } while (ret == Z_OK && zs->avail_in && zs->avail_out);
 156         if (ret == Z_OK && zs->avail_in) {
 157             error_setg(errp, "multifd %u: deflate failed to compress all input",
 158                        p->id);
 159             return -1;
 160         }
 161         if (ret != Z_OK) {
 162             error_setg(errp, "multifd %u: deflate returned %d instead of Z_OK",
 163                        p->id, ret);
 164             return -1;
 165         }
 166         out_size += available - zs->avail_out;
 167     }
 168     p->iov[p->iovs_num].iov_base = z->zbuff;
 169     p->iov[p->iovs_num].iov_len = out_size;
 170     p->iovs_num++;
 171     p->next_packet_size = out_size;
 172     p->flags |= MULTIFD_FLAG_ZLIB;
 173
 174     return 0;
 175 }
 176
 177 /**
 178  * zlib_recv_setup: setup receive side
 179  *
 180  * Create the compressed channel and buffer.
 181  *
 182  * Returns 0 for success or -1 for error
 183  *
 184  * @p: Params for the channel that we are using
 185  * @errp: pointer to an error
 186  */
 187 static int zlib_recv_setup(MultiFDRecvParams *p, Error **errp)
 188 {
 189     struct zlib_data *z = g_new0(struct zlib_data, 1);
 190     z_stream *zs = &z->zs;
 191
 192     p->data = z;
 193     zs->zalloc = Z_NULL;
 194     zs->zfree = Z_NULL;
 195     zs->opaque = Z_NULL;
 196     zs->avail_in = 0;
 197     zs->next_in = Z_NULL;
 198     if (inflateInit(zs) != Z_OK) {
 199         error_setg(errp, "multifd %u: inflate init failed", p->id);
 200         return -1;
 201     }
 202     /* To be safe, we reserve twice the size of the packet */
 203     z->zbuff_len = MULTIFD_PACKET_SIZE * 2;
 204     z->zbuff = g_try_malloc(z->zbuff_len);
 205     if (!z->zbuff) {
 206         inflateEnd(zs);
 207         error_setg(errp, "multifd %u: out of memory for zbuff", p->id);
 208         return -1;
 209     }
 210     return 0;
 211 }
 212
 213 /**
 214  * zlib_recv_cleanup: setup receive side
 215  *
 216  * For no compression this function does nothing.
 217  *
 218  * @p: Params for the channel that we are using
 219  */
 220 static void zlib_recv_cleanup(MultiFDRecvParams *p)
 221 {
 222     struct zlib_data *z = p->data;
 223
 224     inflateEnd(&z->zs);
 225     g_free(z->zbuff);
 226     z->zbuff = NULL;
 227     g_free(p->data);
 228     p->data = NULL;
 229 }
 230
 231 /**
 232  * zlib_recv_pages: read the data from the channel into actual pages
 233  *
 234  * Read the compressed buffer, and uncompress it into the actual
 235  * pages.
 236  *
 237  * Returns 0 for success or -1 for error
 238  *
 239  * @p: Params for the channel that we are using
 240  * @errp: pointer to an error
 241  */
 242 static int zlib_recv_pages(MultiFDRecvParams *p, Error **errp)
 243 {
 244     struct zlib_data *z = p->data;
 245     z_stream *zs = &z->zs;
 246     uint32_t in_size = p->next_packet_size;
 247     /* we measure the change of total_out */
 248     uint32_t out_size = zs->total_out;
 249     uint32_t expected_size = p->normal_num * p->page_size;
 250     uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
 251     int ret;
 252     int i;
 253
 254     if (flags != MULTIFD_FLAG_ZLIB) {
 255         error_setg(errp, "multifd %u: flags received %x flags expected %x",
 256                    p->id, flags, MULTIFD_FLAG_ZLIB);
 257         return -1;
 258     }
 259     ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp);
 260
 261     if (ret != 0) {
 262         return ret;
 263     }
 264
 265     zs->avail_in = in_size;
 266     zs->next_in = z->zbuff;
 267
 268     for (i = 0; i < p->normal_num; i++) {
 269         int flush = Z_NO_FLUSH;
 270         unsigned long start = zs->total_out;
 271
 272         if (i == p->normal_num - 1) {
 273             flush = Z_SYNC_FLUSH;
 274         }
 275
 276         zs->avail_out = p->page_size;
 277         zs->next_out = p->host + p->normal[i];
 278
 279         /*
 280          * Welcome to inflate semantics
 281          *
 282          * We need to loop while:
 283          * - return is Z_OK
 284          * - there are input available
 285          * - we haven't completed a full page
 286          */
 287         do {
 288             ret = inflate(zs, flush);
 289         } while (ret == Z_OK && zs->avail_in
 290                              && (zs->total_out - start) < p->page_size);
 291         if (ret == Z_OK && (zs->total_out - start) < p->page_size) {
 292             error_setg(errp, "multifd %u: inflate generated too few output",
 293                        p->id);
 294             return -1;
 295         }
 296         if (ret != Z_OK) {
 297             error_setg(errp, "multifd %u: inflate returned %d instead of Z_OK",
 298                        p->id, ret);
 299             return -1;
 300         }
 301     }
 302     out_size = zs->total_out - out_size;
 303     if (out_size != expected_size) {
 304         error_setg(errp, "multifd %u: packet size received %u size expected %u",
 305                    p->id, out_size, expected_size);
 306         return -1;
 307     }
 308     return 0;
 309 }
 310
 311 static MultiFDMethods multifd_zlib_ops = {
 312     .send_setup = zlib_send_setup,
 313     .send_cleanup = zlib_send_cleanup,
 314     .send_prepare = zlib_send_prepare,
 315     .recv_setup = zlib_recv_setup,
 316     .recv_cleanup = zlib_recv_cleanup,
 317     .recv_pages = zlib_recv_pages
 318 };
 319
 320 static void multifd_zlib_register(void)
 321 {
 322     multifd_register_ops(MULTIFD_COMPRESSION_ZLIB, &multifd_zlib_ops);
 323 }
 324
 325 migration_init(multifd_zlib_register);