migration/multifd-zlib.c - qemu - Git at Google

 /*
  * 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 maxium 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->data = z;
     return 0;

 err_free_zbuff:
     g_free(z->zbuff);
 err_deflate_end:
     deflateEnd(&z->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->data;

     deflateEnd(&z->zs);
     g_free(z->zbuff);
     z->zbuff = NULL;
     g_free(z->buf);
     z->buf = NULL;
     g_free(p->data);
     p->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)
 {
     struct zlib_data *z = p->data;
     z_stream *zs = &z->zs;
     uint32_t out_size = 0;
     int ret;
     uint32_t i;

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

         if (i == p->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 + p->normal[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;
     p->flags |= MULTIFD_FLAG_ZLIB;

     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->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->data;

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

 /**
  * zlib_recv_pages: 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_pages(MultiFDRecvParams *p, Error **errp)
 {
     struct zlib_data *z = p->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;
     }
     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;

         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_pages = zlib_recv_pages
 };

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

 migration_init(multifd_zlib_register);
	/*
	* 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 maxium 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->data = z;
	return 0;

	err_free_zbuff:
	g_free(z->zbuff);
	err_deflate_end:
	deflateEnd(&z->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->data;

	deflateEnd(&z->zs);
	g_free(z->zbuff);
	z->zbuff = NULL;
	g_free(z->buf);
	z->buf = NULL;
	g_free(p->data);
	p->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)
	{
	struct zlib_data *z = p->data;
	z_stream *zs = &z->zs;
	uint32_t out_size = 0;
	int ret;
	uint32_t i;

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

	if (i == p->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 + p->normal[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;
	p->flags \|= MULTIFD_FLAG_ZLIB;

	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->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->data;

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

	/**
	* zlib_recv_pages: 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_pages(MultiFDRecvParams p, Error *errp)
	{
	struct zlib_data *z = p->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;
	}
	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;

	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_pages = zlib_recv_pages
	};

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

	migration_init(multifd_zlib_register);