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 "multifd.h"
  22
  23 struct zlib_data {
  24     /* stream for compression */
  25     z_stream zs;
  26     /* compressed buffer */
  27     uint8_t *zbuff;
  28     /* size of compressed buffer */
  29     uint32_t zbuff_len;
  30     /* uncompressed buffer of size qemu_target_page_size() */
  31     uint8_t *buf;
  32 };
  33
  34 /* Multifd zlib compression */
  35
  36 /**
  37  * zlib_send_setup: setup send side
  38  *
  39  * Setup each channel with zlib compression.
  40  *
  41  * Returns 0 for success or -1 for error
  42  *
  43  * @p: Params for the channel that we are using
  44  * @errp: pointer to an error
  45  */
  46 static int zlib_send_setup(MultiFDSendParams *p, Error **errp)
  47 {
  48     struct zlib_data *z = g_new0(struct zlib_data, 1);
  49     z_stream *zs = &z->zs;
  50     const char *err_msg;
  51
  52     zs->zalloc = Z_NULL;
  53     zs->zfree = Z_NULL;
  54     zs->opaque = Z_NULL;
  55     if (deflateInit(zs, migrate_multifd_zlib_level()) != Z_OK) {
  56         err_msg = "deflate init failed";
  57         goto err_free_z;
  58     }
  59     /* This is the maxium size of the compressed buffer */
  60     z->zbuff_len = compressBound(MULTIFD_PACKET_SIZE);
  61     z->zbuff = g_try_malloc(z->zbuff_len);
  62     if (!z->zbuff) {
  63         err_msg = "out of memory for zbuff";
  64         goto err_deflate_end;
  65     }
  66     z->buf = g_try_malloc(qemu_target_page_size());
  67     if (!z->buf) {
  68         err_msg = "out of memory for buf";
  69         goto err_free_zbuff;
  70     }
  71     p->data = z;
  72     return 0;
  73
  74 err_free_zbuff:
  75     g_free(z->zbuff);
  76 err_deflate_end:
  77     deflateEnd(&z->zs);
  78 err_free_z:
  79     g_free(z);
  80     error_setg(errp, "multifd %u: %s", p->id, err_msg);
  81     return -1;
  82 }
  83
  84 /**
  85  * zlib_send_cleanup: cleanup send side
  86  *
  87  * Close the channel and return memory.
  88  *
  89  * @p: Params for the channel that we are using
  90  * @errp: pointer to an error
  91  */
  92 static void zlib_send_cleanup(MultiFDSendParams *p, Error **errp)
  93 {
  94     struct zlib_data *z = p->data;
  95
  96     deflateEnd(&z->zs);
  97     g_free(z->zbuff);
  98     z->zbuff = NULL;
  99     g_free(z->buf);
 100     z->buf = NULL;
 101     g_free(p->data);
 102     p->data = NULL;
 103 }
 104
 105 /**
 106  * zlib_send_prepare: prepare date to be able to send
 107  *
 108  * Create a compressed buffer with all the pages that we are going to
 109  * send.
 110  *
 111  * Returns 0 for success or -1 for error
 112  *
 113  * @p: Params for the channel that we are using
 114  * @errp: pointer to an error
 115  */
 116 static int zlib_send_prepare(MultiFDSendParams *p, Error **errp)
 117 {
 118     struct zlib_data *z = p->data;
 119     size_t page_size = qemu_target_page_size();
 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], page_size);
 139         zs->avail_in = 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     size_t page_size = qemu_target_page_size();
 246     z_stream *zs = &z->zs;
 247     uint32_t in_size = p->next_packet_size;
 248     /* we measure the change of total_out */
 249     uint32_t out_size = zs->total_out;
 250     uint32_t expected_size = p->normal_num * page_size;
 251     uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
 252     int ret;
 253     int i;
 254
 255     if (flags != MULTIFD_FLAG_ZLIB) {
 256         error_setg(errp, "multifd %u: flags received %x flags expected %x",
 257                    p->id, flags, MULTIFD_FLAG_ZLIB);
 258         return -1;
 259     }
 260     ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp);
 261
 262     if (ret != 0) {
 263         return ret;
 264     }
 265
 266     zs->avail_in = in_size;
 267     zs->next_in = z->zbuff;
 268
 269     for (i = 0; i < p->normal_num; i++) {
 270         int flush = Z_NO_FLUSH;
 271         unsigned long start = zs->total_out;
 272
 273         if (i == p->normal_num - 1) {
 274             flush = Z_SYNC_FLUSH;
 275         }
 276
 277         zs->avail_out = page_size;
 278         zs->next_out = p->host + p->normal[i];
 279
 280         /*
 281          * Welcome to inflate semantics
 282          *
 283          * We need to loop while:
 284          * - return is Z_OK
 285          * - there are input available
 286          * - we haven't completed a full page
 287          */
 288         do {
 289             ret = inflate(zs, flush);
 290         } while (ret == Z_OK && zs->avail_in
 291                              && (zs->total_out - start) < page_size);
 292         if (ret == Z_OK && (zs->total_out - start) < page_size) {
 293             error_setg(errp, "multifd %u: inflate generated too few output",
 294                        p->id);
 295             return -1;
 296         }
 297         if (ret != Z_OK) {
 298             error_setg(errp, "multifd %u: inflate returned %d instead of Z_OK",
 299                        p->id, ret);
 300             return -1;
 301         }
 302     }
 303     out_size = zs->total_out - out_size;
 304     if (out_size != expected_size) {
 305         error_setg(errp, "multifd %u: packet size received %u size expected %u",
 306                    p->id, out_size, expected_size);
 307         return -1;
 308     }
 309     return 0;
 310 }
 311
 312 static MultiFDMethods multifd_zlib_ops = {
 313     .send_setup = zlib_send_setup,
 314     .send_cleanup = zlib_send_cleanup,
 315     .send_prepare = zlib_send_prepare,
 316     .recv_setup = zlib_recv_setup,
 317     .recv_cleanup = zlib_recv_cleanup,
 318     .recv_pages = zlib_recv_pages
 319 };
 320
 321 static void multifd_zlib_register(void)
 322 {
 323     multifd_register_ops(MULTIFD_COMPRESSION_ZLIB, &multifd_zlib_ops);
 324 }
 325
 326 migration_init(multifd_zlib_register);