multifd: Add zstd compression multifd support

Signed-off-by: Juan Quintela <quintela@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

hw/core/qdev-properties.c

@@ -645,7 +645,7 @@ const PropertyInfo qdev_prop_fdc_drive_type = {
 const PropertyInfo qdev_prop_multifd_compression = {
     .name = "MultiFDCompression",
     .description = "multifd_compression values, "
-                   "none/zlib",
+                   "none/zlib/zstd",
     .enum_table = &MultiFDCompression_lookup,
     .get = get_enum,
     .set = set_enum,

migration/Makefile.objs

@@ -9,6 +9,7 @@ common-obj-y += qjson.o
 common-obj-y += block-dirty-bitmap.o
 common-obj-y += multifd.o
 common-obj-y += multifd-zlib.o
+common-obj-$(CONFIG_ZSTD) += multifd-zstd.o
 
 common-obj-$(CONFIG_RDMA) += rdma.o
 

migration/multifd-zstd.c

@@ -0,0 +1,339 @@
+/*
+ * 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 <zstd.h>
+#include "qemu/rcu.h"
+#include "exec/target_page.h"
+#include "qapi/error.h"
+#include "migration.h"
+#include "trace.h"
+#include "multifd.h"
+
+struct zstd_data {
+    /* stream for compression */
+    ZSTD_CStream *zcs;
+    /* stream for decompression */
+    ZSTD_DStream *zds;
+    /* buffers */
+    ZSTD_inBuffer in;
+    ZSTD_outBuffer out;
+    /* compressed buffer */
+    uint8_t *zbuff;
+    /* size of compressed buffer */
+    uint32_t zbuff_len;
+};
+
+/* Multifd zstd compression */
+
+/**
+ * zstd_send_setup: setup send side
+ *
+ * Setup each channel with zstd 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 zstd_send_setup(MultiFDSendParams *p, Error **errp)
+{
+    uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size();
+    struct zstd_data *z = g_new0(struct zstd_data, 1);
+    int res;
+
+    p->data = z;
+    z->zcs = ZSTD_createCStream();
+    if (!z->zcs) {
+        g_free(z);
+        error_setg(errp, "multifd %d: zstd createCStream failed", p->id);
+        return -1;
+    }
+
+    res = ZSTD_initCStream(z->zcs, migrate_multifd_zstd_level());
+    if (ZSTD_isError(res)) {
+        ZSTD_freeCStream(z->zcs);
+        g_free(z);
+        error_setg(errp, "multifd %d: initCStream failed with error %s",
+                   p->id, ZSTD_getErrorName(res));
+        return -1;
+    }
+    /* We will never have more than page_count pages */
+    z->zbuff_len = page_count * qemu_target_page_size();
+    z->zbuff_len *= 2;
+    z->zbuff = g_try_malloc(z->zbuff_len);
+    if (!z->zbuff) {
+        ZSTD_freeCStream(z->zcs);
+        g_free(z);
+        error_setg(errp, "multifd %d: out of memory for zbuff", p->id);
+        return -1;
+    }
+    return 0;
+}
+
+/**
+ * zstd_send_cleanup: cleanup send side
+ *
+ * Close the channel and return memory.
+ *
+ * @p: Params for the channel that we are using
+ */
+static void zstd_send_cleanup(MultiFDSendParams *p, Error **errp)
+{
+    struct zstd_data *z = p->data;
+
+    ZSTD_freeCStream(z->zcs);
+    z->zcs = NULL;
+    g_free(z->zbuff);
+    z->zbuff = NULL;
+    g_free(p->data);
+    p->data = NULL;
+}
+
+/**
+ * zstd_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
+ * @used: number of pages used
+ */
+static int zstd_send_prepare(MultiFDSendParams *p, uint32_t used, Error **errp)
+{
+    struct iovec *iov = p->pages->iov;
+    struct zstd_data *z = p->data;
+    int ret;
+    uint32_t i;
+
+    z->out.dst = z->zbuff;
+    z->out.size = z->zbuff_len;
+    z->out.pos = 0;
+
+    for (i = 0; i < used; i++) {
+        ZSTD_EndDirective flush = ZSTD_e_continue;
+
+        if (i == used - 1) {
+            flush = ZSTD_e_flush;
+        }
+        z->in.src = iov[i].iov_base;
+        z->in.size = iov[i].iov_len;
+        z->in.pos = 0;
+
+        /*
+         * Welcome to compressStream2 semantics
+         *
+         * We need to loop while:
+         * - return is > 0
+         * - there is input available
+         * - there is output space free
+         */
+        do {
+            ret = ZSTD_compressStream2(z->zcs, &z->out, &z->in, flush);
+        } while (ret > 0 && (z->in.size - z->in.pos > 0)
+                         && (z->out.size - z->out.pos > 0));
+        if (ret > 0 && (z->in.size - z->in.pos > 0)) {
+            error_setg(errp, "multifd %d: compressStream buffer too small",
+                       p->id);
+            return -1;
+        }
+        if (ZSTD_isError(ret)) {
+            error_setg(errp, "multifd %d: compressStream error %s",
+                       p->id, ZSTD_getErrorName(ret));
+            return -1;
+        }
+    }
+    p->next_packet_size = z->out.pos;
+    p->flags |= MULTIFD_FLAG_ZSTD;
+
+    return 0;
+}
+
+/**
+ * zstd_send_write: do the actual write of the data
+ *
+ * Do the actual write of the comprresed buffer.
+ *
+ * Returns 0 for success or -1 for error
+ *
+ * @p: Params for the channel that we are using
+ * @used: number of pages used
+ * @errp: pointer to an error
+ */
+static int zstd_send_write(MultiFDSendParams *p, uint32_t used, Error **errp)
+{
+    struct zstd_data *z = p->data;
+
+    return qio_channel_write_all(p->c, (void *)z->zbuff, p->next_packet_size,
+                                 errp);
+}
+
+/**
+ * zstd_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 zstd_recv_setup(MultiFDRecvParams *p, Error **errp)
+{
+    uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size();
+    struct zstd_data *z = g_new0(struct zstd_data, 1);
+    int ret;
+
+    p->data = z;
+    z->zds = ZSTD_createDStream();
+    if (!z->zds) {
+        g_free(z);
+        error_setg(errp, "multifd %d: zstd createDStream failed", p->id);
+        return -1;
+    }
+
+    ret = ZSTD_initDStream(z->zds);
+    if (ZSTD_isError(ret)) {
+        ZSTD_freeDStream(z->zds);
+        g_free(z);
+        error_setg(errp, "multifd %d: initDStream failed with error %s",
+                   p->id, ZSTD_getErrorName(ret));
+        return -1;
+    }
+
+    /* We will never have more than page_count pages */
+    z->zbuff_len = page_count * qemu_target_page_size();
+    /* We know compression "could" use more space */
+    z->zbuff_len *= 2;
+    z->zbuff = g_try_malloc(z->zbuff_len);
+    if (!z->zbuff) {
+        ZSTD_freeDStream(z->zds);
+        g_free(z);
+        error_setg(errp, "multifd %d: out of memory for zbuff", p->id);
+        return -1;
+    }
+    return 0;
+}
+
+/**
+ * zstd_recv_cleanup: setup receive side
+ *
+ * For no compression this function does nothing.
+ *
+ * @p: Params for the channel that we are using
+ */
+static void zstd_recv_cleanup(MultiFDRecvParams *p)
+{
+    struct zstd_data *z = p->data;
+
+    ZSTD_freeDStream(z->zds);
+    z->zds = NULL;
+    g_free(z->zbuff);
+    z->zbuff = NULL;
+    g_free(p->data);
+    p->data = NULL;
+}
+
+/**
+ * zstd_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
+ * @used: number of pages used
+ * @errp: pointer to an error
+ */
+static int zstd_recv_pages(MultiFDRecvParams *p, uint32_t used, Error **errp)
+{
+    uint32_t in_size = p->next_packet_size;
+    uint32_t out_size = 0;
+    uint32_t expected_size = used * qemu_target_page_size();
+    uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
+    struct zstd_data *z = p->data;
+    int ret;
+    int i;
+
+    if (flags != MULTIFD_FLAG_ZSTD) {
+        error_setg(errp, "multifd %d: flags received %x flags expected %x",
+                   p->id, flags, MULTIFD_FLAG_ZSTD);
+        return -1;
+    }
+    ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp);
+
+    if (ret != 0) {
+        return ret;
+    }
+
+    z->in.src = z->zbuff;
+    z->in.size = in_size;
+    z->in.pos = 0;
+
+    for (i = 0; i < used; i++) {
+        struct iovec *iov = &p->pages->iov[i];
+
+        z->out.dst = iov->iov_base;
+        z->out.size = iov->iov_len;
+        z->out.pos = 0;
+
+        /*
+         * Welcome to decompressStream semantics
+         *
+         * We need to loop while:
+         * - return is > 0
+         * - there is input available
+         * - we haven't put out a full page
+         */
+        do {
+            ret = ZSTD_decompressStream(z->zds, &z->out, &z->in);
+        } while (ret > 0 && (z->in.size - z->in.pos > 0)
+                         && (z->out.pos < iov->iov_len));
+        if (ret > 0 && (z->out.pos < iov->iov_len)) {
+            error_setg(errp, "multifd %d: decompressStream buffer too small",
+                       p->id);
+            return -1;
+        }
+        if (ZSTD_isError(ret)) {
+            error_setg(errp, "multifd %d: decompressStream returned %s",
+                       p->id, ZSTD_getErrorName(ret));
+            return ret;
+        }
+        out_size += z->out.pos;
+    }
+    if (out_size != expected_size) {
+        error_setg(errp, "multifd %d: packet size received %d size expected %d",
+                   p->id, out_size, expected_size);
+        return -1;
+    }
+    return 0;
+}
+
+static MultiFDMethods multifd_zstd_ops = {
+    .send_setup = zstd_send_setup,
+    .send_cleanup = zstd_send_cleanup,
+    .send_prepare = zstd_send_prepare,
+    .send_write = zstd_send_write,
+    .recv_setup = zstd_recv_setup,
+    .recv_cleanup = zstd_recv_cleanup,
+    .recv_pages = zstd_recv_pages
+};
+
+static void multifd_zstd_register(void)
+{
+    multifd_register_ops(MULTIFD_COMPRESSION_ZSTD, &multifd_zstd_ops);
+}
+
+migration_init(multifd_zstd_register);

migration/multifd.h

@@ -31,6 +31,7 @@ int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset);
 /* we need to be compatible. Before compression value was 0 */
 #define MULTIFD_FLAG_NOCOMP (0 << 1)
 #define MULTIFD_FLAG_ZLIB (1 << 1)
+#define MULTIFD_FLAG_ZSTD (2 << 1)
 
 /* This value needs to be a multiple of qemu_target_page_size() */
 #define MULTIFD_PACKET_SIZE (512 * 1024)

migration/ram.c

@@ -28,7 +28,6 @@
 
 #include "qemu/osdep.h"
 #include "cpu.h"
-#include <zlib.h>
 #include "qemu/cutils.h"
 #include "qemu/bitops.h"
 #include "qemu/bitmap.h"

qapi/migration.json

@@ -495,12 +495,14 @@
 #
 # @none: no compression.
 # @zlib: use zlib compression method.
+# @zstd: use zstd compression method.
 #
 # Since: 5.0
 #
 ##
 { 'enum': 'MultiFDCompression',
-  'data': [ 'none', 'zlib' ] }
+  'data': [ 'none', 'zlib',
+            { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] }
 
 ##
 # @MigrationParameter: