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| | // SPDX-License-Identifier: GPL-2.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* migrate.c - Migration sections, layout, and routines
*
* Copyright (c) 2025 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#include <errno.h>
#include <sys/uio.h>
#include "util.h"
#include "ip.h"
#include "passt.h"
#include "inany.h"
#include "flow.h"
#include "flow_table.h"
#include "migrate.h"
/* Current version of migration data */
#define MIGRATE_VERSION 1
/* Magic identifier for migration data */
#define MIGRATE_MAGIC 0xB1BB1D1B0BB1D1B0
/* Migration header to send from source */
static struct migrate_header header = {
.magic = htonll_constant(MIGRATE_MAGIC),
.version = htonl_constant(MIGRATE_VERSION),
};
/**
* migrate_send_block() - Migration stage handler to send verbatim data
* @c: Execution context
* @stage: Migration stage
* @fd: Migration fd
*
* Sends the buffer in @stage->iov over the migration channel.
*/
__attribute__((__unused__))
static int migrate_send_block(struct ctx *c,
const struct migrate_stage *stage, int fd)
{
(void)c;
if (write_remainder(fd, &stage->iov, 1, 0) < 0)
return errno;
return 0;
}
/**
* migrate_recv_block() - Migration stage handler to receive verbatim data
* @c: Execution context
* @stage: Migration stage
* @fd: Migration fd
*
* Reads the buffer in @stage->iov from the migration channel.
*
* #syscalls:vu readv
*/
__attribute__((__unused__))
static int migrate_recv_block(struct ctx *c,
const struct migrate_stage *stage, int fd)
{
(void)c;
if (read_remainder(fd, &stage->iov, 1, 0) < 0)
return errno;
return 0;
}
#define DATA_STAGE(v) \
{ \
.name = #v, \
.source = migrate_send_block, \
.target = migrate_recv_block, \
.iov = { &(v), sizeof(v) }, \
}
/* Stages for version 1 */
static const struct migrate_stage stages_v1[] = {
{
.name = "flow pre",
.target = NULL,
},
{
.name = "flow post",
.source = NULL,
},
{ 0 },
};
/* Set of data versions */
static const struct migrate_version versions[] = {
{
1, stages_v1,
},
{ 0 },
};
/**
* migrate_source() - Migration as source, send state to hypervisor
* @c: Execution context
* @fd: File descriptor for state transfer
*
* Return: 0 on success, positive error code on failure
*/
int migrate_source(struct ctx *c, int fd)
{
const struct migrate_version *v = versions + ARRAY_SIZE(versions) - 1;
const struct migrate_stage *s;
int ret;
ret = write_all_buf(fd, &header, sizeof(header));
if (ret) {
err("Can't send migration header: %s, abort", strerror_(ret));
return ret;
}
for (s = v->s; *s->name; s++) {
if (!s->source)
continue;
debug("Source side migration: %s", s->name);
if ((ret = s->source(c, s, fd))) {
err("Source migration stage %s: %s, abort", s->name,
strerror_(ret));
return ret;
}
}
return 0;
}
/**
* migrate_target_read_header() - Read header in target
* @fd: Descriptor for state transfer
*
* Return: version number on success, 0 on failure with errno set
*/
static uint32_t migrate_target_read_header(int fd)
{
struct migrate_header h;
if (read_all_buf(fd, &h, sizeof(h)))
return 0;
debug("Source magic: 0x%016" PRIx64 ", version: %u",
be64toh(h.magic), ntohl_constant(h.version));
if (ntohll_constant(h.magic) != MIGRATE_MAGIC || !ntohl(h.version)) {
errno = EINVAL;
return 0;
}
return ntohl(h.version);
}
/**
* migrate_target() - Migration as target, receive state from hypervisor
* @c: Execution context
* @fd: File descriptor for state transfer
*
* Return: 0 on success, positive error code on failure
*/
int migrate_target(struct ctx *c, int fd)
{
const struct migrate_version *v;
const struct migrate_stage *s;
uint32_t id;
int ret;
id = migrate_target_read_header(fd);
if (!id) {
ret = errno;
err("Migration header check failed: %s, abort", strerror_(ret));
return ret;
}
for (v = versions; v->id && v->id == id; v++);
if (!v->id) {
err("Unsupported version: %u", id);
return -ENOTSUP;
}
for (s = v->s; *s->name; s++) {
if (!s->target)
continue;
debug("Target side migration: %s", s->name);
if ((ret = s->target(c, s, fd))) {
err("Target migration stage %s: %s, abort", s->name,
strerror_(ret));
return ret;
}
}
return 0;
}
|