aboutsummaryrefslogtreecommitdiff
path: root/migration/multifd-zlib.c
blob: 737a9645d2fe83c3bfb11580a5987b0fac75e5a1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
/*
 * Multifd zlib compression implementation
 *
 * Copyright (c) 2020 Red Hat Inc
 *
 * Authors:
 *  Juan Quintela <quintela@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */

#include "qemu/osdep.h"
#include <zlib.h>
#include "qemu/rcu.h"
#include "exec/ramblock.h"
#include "exec/target_page.h"
#include "qapi/error.h"
#include "migration.h"
#include "trace.h"
#include "options.h"
#include "multifd.h"

struct zlib_data {
    /* stream for compression */
    z_stream zs;
    /* compressed buffer */
    uint8_t *zbuff;
    /* size of compressed buffer */
    uint32_t zbuff_len;
    /* uncompressed buffer of size qemu_target_page_size() */
    uint8_t *buf;
};

/* Multifd zlib compression */

/**
 * zlib_send_setup: setup send side
 *
 * Setup each channel with zlib compression.
 *
 * Returns 0 for success or -1 for error
 *
 * @p: Params for the channel that we are using
 * @errp: pointer to an error
 */
static int zlib_send_setup(MultiFDSendParams *p, Error **errp)
{
    struct zlib_data *z = g_new0(struct zlib_data, 1);
    z_stream *zs = &z->zs;
    const char *err_msg;

    zs->zalloc = Z_NULL;
    zs->zfree = Z_NULL;
    zs->opaque = Z_NULL;
    if (deflateInit(zs, migrate_multifd_zlib_level()) != Z_OK) {
        err_msg = "deflate init failed";
        goto err_free_z;
    }
    /* This is the maximum size of the compressed buffer */
    z->zbuff_len = compressBound(MULTIFD_PACKET_SIZE);
    z->zbuff = g_try_malloc(z->zbuff_len);
    if (!z->zbuff) {
        err_msg = "out of memory for zbuff";
        goto err_deflate_end;
    }
    z->buf = g_try_malloc(qemu_target_page_size());
    if (!z->buf) {
        err_msg = "out of memory for buf";
        goto err_free_zbuff;
    }
    p->compress_data = z;
    return 0;

err_free_zbuff:
    g_free(z->zbuff);
err_deflate_end:
    deflateEnd(zs);
err_free_z:
    g_free(z);
    error_setg(errp, "multifd %u: %s", p->id, err_msg);
    return -1;
}

/**
 * zlib_send_cleanup: cleanup send side
 *
 * Close the channel and return memory.
 *
 * @p: Params for the channel that we are using
 * @errp: pointer to an error
 */
static void zlib_send_cleanup(MultiFDSendParams *p, Error **errp)
{
    struct zlib_data *z = p->compress_data;

    deflateEnd(&z->zs);
    g_free(z->zbuff);
    z->zbuff = NULL;
    g_free(z->buf);
    z->buf = NULL;
    g_free(p->compress_data);
    p->compress_data = NULL;
}

/**
 * zlib_send_prepare: prepare date to be able to send
 *
 * Create a compressed buffer with all the pages that we are going to
 * send.
 *
 * Returns 0 for success or -1 for error
 *
 * @p: Params for the channel that we are using
 * @errp: pointer to an error
 */
static int zlib_send_prepare(MultiFDSendParams *p, Error **errp)
{
    MultiFDPages_t *pages = p->pages;
    struct zlib_data *z = p->compress_data;
    z_stream *zs = &z->zs;
    uint32_t out_size = 0;
    int ret;
    uint32_t i;

    if (!multifd_send_prepare_common(p)) {
        goto out;
    }

    for (i = 0; i < pages->normal_num; i++) {
        uint32_t available = z->zbuff_len - out_size;
        int flush = Z_NO_FLUSH;

        if (i == pages->normal_num - 1) {
            flush = Z_SYNC_FLUSH;
        }

        /*
         * Since the VM might be running, the page may be changing concurrently
         * with compression. zlib does not guarantee that this is safe,
         * therefore copy the page before calling deflate().
         */
        memcpy(z->buf, p->pages->block->host + pages->offset[i], p->page_size);
        zs->avail_in = p->page_size;
        zs->next_in = z->buf;

        zs->avail_out = available;
        zs->next_out = z->zbuff + out_size;

        /*
         * Welcome to deflate semantics
         *
         * We need to loop while:
         * - return is Z_OK
         * - there are stuff to be compressed
         * - there are output space free
         */
        do {
            ret = deflate(zs, flush);
        } while (ret == Z_OK && zs->avail_in && zs->avail_out);
        if (ret == Z_OK && zs->avail_in) {
            error_setg(errp, "multifd %u: deflate failed to compress all input",
                       p->id);
            return -1;
        }
        if (ret != Z_OK) {
            error_setg(errp, "multifd %u: deflate returned %d instead of Z_OK",
                       p->id, ret);
            return -1;
        }
        out_size += available - zs->avail_out;
    }
    p->iov[p->iovs_num].iov_base = z->zbuff;
    p->iov[p->iovs_num].iov_len = out_size;
    p->iovs_num++;
    p->next_packet_size = out_size;

out:
    p->flags |= MULTIFD_FLAG_ZLIB;
    multifd_send_fill_packet(p);
    return 0;
}

/**
 * zlib_recv_setup: setup receive side
 *
 * Create the compressed channel and buffer.
 *
 * Returns 0 for success or -1 for error
 *
 * @p: Params for the channel that we are using
 * @errp: pointer to an error
 */
static int zlib_recv_setup(MultiFDRecvParams *p, Error **errp)
{
    struct zlib_data *z = g_new0(struct zlib_data, 1);
    z_stream *zs = &z->zs;

    p->compress_data = z;
    zs->zalloc = Z_NULL;
    zs->zfree = Z_NULL;
    zs->opaque = Z_NULL;
    zs->avail_in = 0;
    zs->next_in = Z_NULL;
    if (inflateInit(zs) != Z_OK) {
        error_setg(errp, "multifd %u: inflate init failed", p->id);
        return -1;
    }
    /* To be safe, we reserve twice the size of the packet */
    z->zbuff_len = MULTIFD_PACKET_SIZE * 2;
    z->zbuff = g_try_malloc(z->zbuff_len);
    if (!z->zbuff) {
        inflateEnd(zs);
        error_setg(errp, "multifd %u: out of memory for zbuff", p->id);
        return -1;
    }
    return 0;
}

/**
 * zlib_recv_cleanup: setup receive side
 *
 * For no compression this function does nothing.
 *
 * @p: Params for the channel that we are using
 */
static void zlib_recv_cleanup(MultiFDRecvParams *p)
{
    struct zlib_data *z = p->compress_data;

    inflateEnd(&z->zs);
    g_free(z->zbuff);
    z->zbuff = NULL;
    g_free(p->compress_data);
    p->compress_data = NULL;
}

/**
 * zlib_recv: read the data from the channel into actual pages
 *
 * Read the compressed buffer, and uncompress it into the actual
 * pages.
 *
 * Returns 0 for success or -1 for error
 *
 * @p: Params for the channel that we are using
 * @errp: pointer to an error
 */
static int zlib_recv(MultiFDRecvParams *p, Error **errp)
{
    struct zlib_data *z = p->compress_data;
    z_stream *zs = &z->zs;
    uint32_t in_size = p->next_packet_size;
    /* we measure the change of total_out */
    uint32_t out_size = zs->total_out;
    uint32_t expected_size = p->normal_num * p->page_size;
    uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
    int ret;
    int i;

    if (flags != MULTIFD_FLAG_ZLIB) {
        error_setg(errp, "multifd %u: flags received %x flags expected %x",
                   p->id, flags, MULTIFD_FLAG_ZLIB);
        return -1;
    }

    multifd_recv_zero_page_process(p);

    if (!p->normal_num) {
        assert(in_size == 0);
        return 0;
    }

    ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp);

    if (ret != 0) {
        return ret;
    }

    zs->avail_in = in_size;
    zs->next_in = z->zbuff;

    for (i = 0; i < p->normal_num; i++) {
        int flush = Z_NO_FLUSH;
        unsigned long start = zs->total_out;

        ramblock_recv_bitmap_set_offset(p->block, p->normal[i]);
        if (i == p->normal_num - 1) {
            flush = Z_SYNC_FLUSH;
        }

        zs->avail_out = p->page_size;
        zs->next_out = p->host + p->normal[i];

        /*
         * Welcome to inflate semantics
         *
         * We need to loop while:
         * - return is Z_OK
         * - there are input available
         * - we haven't completed a full page
         */
        do {
            ret = inflate(zs, flush);
        } while (ret == Z_OK && zs->avail_in
                             && (zs->total_out - start) < p->page_size);
        if (ret == Z_OK && (zs->total_out - start) < p->page_size) {
            error_setg(errp, "multifd %u: inflate generated too few output",
                       p->id);
            return -1;
        }
        if (ret != Z_OK) {
            error_setg(errp, "multifd %u: inflate returned %d instead of Z_OK",
                       p->id, ret);
            return -1;
        }
    }
    out_size = zs->total_out - out_size;
    if (out_size != expected_size) {
        error_setg(errp, "multifd %u: packet size received %u size expected %u",
                   p->id, out_size, expected_size);
        return -1;
    }

    return 0;
}

static MultiFDMethods multifd_zlib_ops = {
    .send_setup = zlib_send_setup,
    .send_cleanup = zlib_send_cleanup,
    .send_prepare = zlib_send_prepare,
    .recv_setup = zlib_recv_setup,
    .recv_cleanup = zlib_recv_cleanup,
    .recv = zlib_recv
};

static void multifd_zlib_register(void)
{
    multifd_register_ops(MULTIFD_COMPRESSION_ZLIB, &multifd_zlib_ops);
}

migration_init(multifd_zlib_register);