Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 hw/core/qdev-properties.c    |   2 +-
 migration/Makefile.objs      |   1 +
 migration/migration.c        |   9 +
 migration/migration.h        |   1 +
 migration/multifd-zstd.c     | 337 +++++++++++++++++++++++++++++++++++
 migration/multifd.h          |   2 +-
 migration/ram.c              |   1 -
 qapi/migration.json          |   4 +-
 tests/qtest/migration-test.c |  10 ++
 9 files changed, 363 insertions(+), 4 deletions(-)
 create mode 100644 migration/multifd-zstd.c

diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index bf88a50cdf..9440ca78c3 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -645,7 +645,7 @@ const PropertyInfo qdev_prop_fdc_drive_type = {
 const PropertyInfo qdev_prop_multifd_method = {
     .name = "MultiFDMethod",
     .description = "multifd_method values, "
-                   "none/zlib",
+                   "none/zlib/zstd",
     .enum_table = &MultiFDMethod_lookup,
     .get = get_enum,
     .set = set_enum,
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index 0308caa5c5..0fc619e380 100644
--- a/migration/Makefile.objs
+++ b/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
 
diff --git a/migration/migration.c b/migration/migration.c
index b690500545..aff081128c 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2285,6 +2285,15 @@ int migrate_multifd_zlib_level(void)
     return s->parameters.multifd_zlib_level;
 }
 
+int migrate_multifd_zstd_level(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->parameters.multifd_zstd_level;
+}
+
 int migrate_use_xbzrle(void)
 {
     MigrationState *s;
diff --git a/migration/migration.h b/migration/migration.h
index 95e9c196ff..2eb72aee0a 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -302,6 +302,7 @@ bool migrate_pause_before_switchover(void);
 int migrate_multifd_channels(void);
 MultiFDMethod migrate_multifd_method(void);
 int migrate_multifd_zlib_level(void);
+int migrate_multifd_zstd_level(void);
 
 int migrate_use_xbzrle(void);
 int64_t migrate_xbzrle_cache_size(void);
diff --git a/migration/multifd-zstd.c b/migration/multifd-zstd.c
new file mode 100644
index 0000000000..6383a8a898
--- /dev/null
+++ b/migration/multifd-zstd.c
@@ -0,0 +1,337 @@
+/*
+ * 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", p->id);
+        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 res;
+
+    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;
+    }
+
+    res = ZSTD_initDStream(z->zds);
+    if (ZSTD_isError(res)) {
+        ZSTD_freeDStream(z->zds);
+        g_free(z);
+        error_setg(errp, "multifd %d: initDStream failed", p->id);
+        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_METHOD_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_METHOD_ZSTD, &multifd_zstd_ops);
+}
+
+migration_init(multifd_zstd_register);
diff --git a/migration/multifd.h b/migration/multifd.h
index 3fa5132f1d..621db316c1 100644
--- a/migration/multifd.h
+++ b/migration/multifd.h
@@ -30,6 +30,7 @@ int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset);
 #define MULTIFD_FLAG_METHOD_MASK (7 << 1)
 #define MULTIFD_FLAG_NOCOMP (1 << 1)
 #define MULTIFD_FLAG_ZLIB (2 << 1)
+#define MULTIFD_FLAG_ZSTD (3 << 1)
 
 /* This value needs to be a multiple of qemu_target_page_size() */
 #define MULTIFD_PACKET_SIZE (512 * 1024)
@@ -163,6 +164,5 @@ typedef struct {
 } MultiFDMethods;
 
 void multifd_register_ops(int method, MultiFDMethods *ops);
-
 #endif
 
diff --git a/migration/ram.c b/migration/ram.c
index 73a141bb60..0ef68798d2 100644
--- a/migration/ram.c
+++ b/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"
diff --git a/qapi/migration.json b/qapi/migration.json
index bb5cb6b4f4..8ccec7fa79 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -495,12 +495,14 @@
 #
 # @none: no compression.
 # @zlib: use zlib compression method.
+# @zstd: use zstd compression method.
 #
 # Since: 5.0
 #
 ##
 { 'enum': 'MultiFDMethod',
-  'data': [ 'none', 'zlib' ] }
+  'data': [ 'none', 'zlib',
+            { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] }
 
 ##
 # @MigrationParameter:
diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index 8effed205d..ec9be28bc9 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -1318,6 +1318,13 @@ static void test_multifd_tcp_zlib(void)
     test_multifd_tcp("zlib");
 }
 
+#ifdef CONFIG_ZSTD
+static void test_multifd_tcp_zstd(void)
+{
+    test_multifd_tcp("zstd");
+}
+#endif
+
 /*
  * This test does:
  *  source               target
@@ -1481,6 +1488,9 @@ int main(int argc, char **argv)
     qtest_add_func("/migration/multifd/tcp/none", test_multifd_tcp_none);
     qtest_add_func("/migration/multifd/tcp/cancel", test_multifd_tcp_cancel);
     qtest_add_func("/migration/multifd/tcp/zlib", test_multifd_tcp_zlib);
+#ifdef CONFIG_ZSTD
+    qtest_add_func("/migration/multifd/tcp/zstd", test_multifd_tcp_zstd);
+#endif
 
     ret = g_test_run();
 
-- 
2.24.1

Juan Quintela <quintela@redhat.com> writes:

> Signed-off-by: Juan Quintela <quintela@redhat.com>

For QAPI:
Acked-by: Markus Armbruster <armbru@redhat.com>

* Juan Quintela (quintela@redhat.com) wrote:
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  hw/core/qdev-properties.c    |   2 +-
>  migration/Makefile.objs      |   1 +
>  migration/migration.c        |   9 +
>  migration/migration.h        |   1 +
>  migration/multifd-zstd.c     | 337 +++++++++++++++++++++++++++++++++++
>  migration/multifd.h          |   2 +-
>  migration/ram.c              |   1 -
>  qapi/migration.json          |   4 +-
>  tests/qtest/migration-test.c |  10 ++
>  9 files changed, 363 insertions(+), 4 deletions(-)
>  create mode 100644 migration/multifd-zstd.c
> 
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index bf88a50cdf..9440ca78c3 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -645,7 +645,7 @@ const PropertyInfo qdev_prop_fdc_drive_type = {
>  const PropertyInfo qdev_prop_multifd_method = {
>      .name = "MultiFDMethod",
>      .description = "multifd_method values, "
> -                   "none/zlib",
> +                   "none/zlib/zstd",
>      .enum_table = &MultiFDMethod_lookup,
>      .get = get_enum,
>      .set = set_enum,
> diff --git a/migration/Makefile.objs b/migration/Makefile.objs
> index 0308caa5c5..0fc619e380 100644
> --- a/migration/Makefile.objs
> +++ b/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
>  
> diff --git a/migration/migration.c b/migration/migration.c
> index b690500545..aff081128c 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2285,6 +2285,15 @@ int migrate_multifd_zlib_level(void)
>      return s->parameters.multifd_zlib_level;
>  }
>  
> +int migrate_multifd_zstd_level(void)
> +{
> +    MigrationState *s;
> +
> +    s = migrate_get_current();
> +
> +    return s->parameters.multifd_zstd_level;
> +}
> +
>  int migrate_use_xbzrle(void)
>  {
>      MigrationState *s;
> diff --git a/migration/migration.h b/migration/migration.h
> index 95e9c196ff..2eb72aee0a 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -302,6 +302,7 @@ bool migrate_pause_before_switchover(void);
>  int migrate_multifd_channels(void);
>  MultiFDMethod migrate_multifd_method(void);
>  int migrate_multifd_zlib_level(void);
> +int migrate_multifd_zstd_level(void);
>  
>  int migrate_use_xbzrle(void);
>  int64_t migrate_xbzrle_cache_size(void);
> diff --git a/migration/multifd-zstd.c b/migration/multifd-zstd.c
> new file mode 100644
> index 0000000000..6383a8a898
> --- /dev/null
> +++ b/migration/multifd-zstd.c
> @@ -0,0 +1,337 @@
> +/*
> + * 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", p->id);

It might be useful to print 'res' here - you seem to decode it on the
receive side.

> +        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 res;
> +
> +    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;
> +    }
> +
> +    res = ZSTD_initDStream(z->zds);
> +    if (ZSTD_isError(res)) {
> +        ZSTD_freeDStream(z->zds);
> +        g_free(z);
> +        error_setg(errp, "multifd %d: initDStream failed", p->id);
> +        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_METHOD_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_METHOD_ZSTD, &multifd_zstd_ops);
> +}
> +
> +migration_init(multifd_zstd_register);
> diff --git a/migration/multifd.h b/migration/multifd.h
> index 3fa5132f1d..621db316c1 100644
> --- a/migration/multifd.h
> +++ b/migration/multifd.h
> @@ -30,6 +30,7 @@ int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset);
>  #define MULTIFD_FLAG_METHOD_MASK (7 << 1)
>  #define MULTIFD_FLAG_NOCOMP (1 << 1)
>  #define MULTIFD_FLAG_ZLIB (2 << 1)
> +#define MULTIFD_FLAG_ZSTD (3 << 1)
>  
>  /* This value needs to be a multiple of qemu_target_page_size() */
>  #define MULTIFD_PACKET_SIZE (512 * 1024)
> @@ -163,6 +164,5 @@ typedef struct {
>  } MultiFDMethods;
>  
>  void multifd_register_ops(int method, MultiFDMethods *ops);
> -

Oddment.

>  #endif
>  
> diff --git a/migration/ram.c b/migration/ram.c
> index 73a141bb60..0ef68798d2 100644
> --- a/migration/ram.c
> +++ b/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"
> diff --git a/qapi/migration.json b/qapi/migration.json
> index bb5cb6b4f4..8ccec7fa79 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -495,12 +495,14 @@
>  #
>  # @none: no compression.
>  # @zlib: use zlib compression method.
> +# @zstd: use zstd compression method.
>  #
>  # Since: 5.0
>  #
>  ##
>  { 'enum': 'MultiFDMethod',
> -  'data': [ 'none', 'zlib' ] }
> +  'data': [ 'none', 'zlib',
> +            { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] }
>  
>  ##
>  # @MigrationParameter:
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 8effed205d..ec9be28bc9 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -1318,6 +1318,13 @@ static void test_multifd_tcp_zlib(void)
>      test_multifd_tcp("zlib");
>  }
>  
> +#ifdef CONFIG_ZSTD
> +static void test_multifd_tcp_zstd(void)
> +{
> +    test_multifd_tcp("zstd");
> +}
> +#endif
> +
>  /*
>   * This test does:
>   *  source               target
> @@ -1481,6 +1488,9 @@ int main(int argc, char **argv)
>      qtest_add_func("/migration/multifd/tcp/none", test_multifd_tcp_none);
>      qtest_add_func("/migration/multifd/tcp/cancel", test_multifd_tcp_cancel);
>      qtest_add_func("/migration/multifd/tcp/zlib", test_multifd_tcp_zlib);
> +#ifdef CONFIG_ZSTD
> +    qtest_add_func("/migration/multifd/tcp/zstd", test_multifd_tcp_zstd);
> +#endif
>  
>      ret = g_test_run();
>  
> -- 
> 2.24.1
> 

Minor comments above; but other than those it looks OK to me, but I've
not used zstd before:


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

"Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> * Juan Quintela (quintela@redhat.com) wrote:
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>>  hw/core/qdev-properties.c    |   2 +-
>>  migration/Makefile.objs      |   1 +
>>  migration/migration.c        |   9 +
>>  migration/migration.h        |   1 +
>>  migration/multifd-zstd.c     | 337 +++++++++++++++++++++++++++++++++++
>>  migration/multifd.h          |   2 +-
>>  migration/ram.c              |   1 -
>>  qapi/migration.json          |   4 +-
>>  tests/qtest/migration-test.c |  10 ++
>>  9 files changed, 363 insertions(+), 4 deletions(-)
>>  create mode 100644 migration/multifd-zstd.c

>> +    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", p->id);
>
> It might be useful to print 'res' here - you seem to decode it on the
> receive side.

Fixed all callers.

>> @@ -163,6 +164,5 @@ typedef struct {
>>  } MultiFDMethods;
>>  
>>  void multifd_register_ops(int method, MultiFDMethods *ops);
>> -
>
> Oddment.

oops.  Removed the chunk.
>
>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Thanks.