Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 911 insertions, 0 deletions

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
new file mode 100644
index 000000000..ff6b45de6
--- /dev/null
+++ b/hw/vfio/migration.c
@@ -0,0 +1,911 @@
+/*
+ * Migration support for VFIO devices
+ *
+ * Copyright NVIDIA, Inc. 2020
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
+#include "qemu/cutils.h"
+#include <linux/vfio.h>
+#include <sys/ioctl.h>
+
+#include "sysemu/runstate.h"
+#include "hw/vfio/vfio-common.h"
+#include "migration/migration.h"
+#include "migration/vmstate.h"
+#include "migration/qemu-file.h"
+#include "migration/register.h"
+#include "migration/blocker.h"
+#include "migration/misc.h"
+#include "qapi/error.h"
+#include "exec/ramlist.h"
+#include "exec/ram_addr.h"
+#include "pci.h"
+#include "trace.h"
+#include "hw/hw.h"
+
+/*
+ * Flags to be used as unique delimiters for VFIO devices in the migration
+ * stream. These flags are composed as:
+ * 0xffffffff => MSB 32-bit all 1s
+ * 0xef10     => Magic ID, represents emulated (virtual) function IO
+ * 0x0000     => 16-bits reserved for flags
+ *
+ * The beginning of state information is marked by _DEV_CONFIG_STATE,
+ * _DEV_SETUP_STATE, or _DEV_DATA_STATE, respectively. The end of a
+ * certain state information is marked by _END_OF_STATE.
+ */
+#define VFIO_MIG_FLAG_END_OF_STATE      (0xffffffffef100001ULL)
+#define VFIO_MIG_FLAG_DEV_CONFIG_STATE  (0xffffffffef100002ULL)
+#define VFIO_MIG_FLAG_DEV_SETUP_STATE   (0xffffffffef100003ULL)
+#define VFIO_MIG_FLAG_DEV_DATA_STATE    (0xffffffffef100004ULL)
+
+static int64_t bytes_transferred;
+
+static inline int vfio_mig_access(VFIODevice *vbasedev, void *val, int count,
+                                  off_t off, bool iswrite)
+{
+    int ret;
+
+    ret = iswrite ? pwrite(vbasedev->fd, val, count, off) :
+                    pread(vbasedev->fd, val, count, off);
+    if (ret < count) {
+        error_report("vfio_mig_%s %d byte %s: failed at offset 0x%"
+                     HWADDR_PRIx", err: %s", iswrite ? "write" : "read", count,
+                     vbasedev->name, off, strerror(errno));
+        return (ret < 0) ? ret : -EINVAL;
+    }
+    return 0;
+}
+
+static int vfio_mig_rw(VFIODevice *vbasedev, __u8 *buf, size_t count,
+                       off_t off, bool iswrite)
+{
+    int ret, done = 0;
+    __u8 *tbuf = buf;
+
+    while (count) {
+        int bytes = 0;
+
+        if (count >= 8 && !(off % 8)) {
+            bytes = 8;
+        } else if (count >= 4 && !(off % 4)) {
+            bytes = 4;
+        } else if (count >= 2 && !(off % 2)) {
+            bytes = 2;
+        } else {
+            bytes = 1;
+        }
+
+        ret = vfio_mig_access(vbasedev, tbuf, bytes, off, iswrite);
+        if (ret) {
+            return ret;
+        }
+
+        count -= bytes;
+        done += bytes;
+        off += bytes;
+        tbuf += bytes;
+    }
+    return done;
+}
+
+#define vfio_mig_read(f, v, c, o)       vfio_mig_rw(f, (__u8 *)v, c, o, false)
+#define vfio_mig_write(f, v, c, o)      vfio_mig_rw(f, (__u8 *)v, c, o, true)
+
+#define VFIO_MIG_STRUCT_OFFSET(f)       \
+                                 offsetof(struct vfio_device_migration_info, f)
+/*
+ * Change the device_state register for device @vbasedev. Bits set in @mask
+ * are preserved, bits set in @value are set, and bits not set in either @mask
+ * or @value are cleared in device_state. If the register cannot be accessed,
+ * the resulting state would be invalid, or the device enters an error state,
+ * an error is returned.
+ */
+
+static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask,
+                                    uint32_t value)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    off_t dev_state_off = region->fd_offset +
+                          VFIO_MIG_STRUCT_OFFSET(device_state);
+    uint32_t device_state;
+    int ret;
+
+    ret = vfio_mig_read(vbasedev, &device_state, sizeof(device_state),
+                        dev_state_off);
+    if (ret < 0) {
+        return ret;
+    }
+
+    device_state = (device_state & mask) | value;
+
+    if (!VFIO_DEVICE_STATE_VALID(device_state)) {
+        return -EINVAL;
+    }
+
+    ret = vfio_mig_write(vbasedev, &device_state, sizeof(device_state),
+                         dev_state_off);
+    if (ret < 0) {
+        int rret;
+
+        rret = vfio_mig_read(vbasedev, &device_state, sizeof(device_state),
+                             dev_state_off);
+
+        if ((rret < 0) || (VFIO_DEVICE_STATE_IS_ERROR(device_state))) {
+            hw_error("%s: Device in error state 0x%x", vbasedev->name,
+                     device_state);
+            return rret ? rret : -EIO;
+        }
+        return ret;
+    }
+
+    migration->device_state = device_state;
+    trace_vfio_migration_set_state(vbasedev->name, device_state);
+    return 0;
+}
+
+static void *get_data_section_size(VFIORegion *region, uint64_t data_offset,
+                                   uint64_t data_size, uint64_t *size)
+{
+    void *ptr = NULL;
+    uint64_t limit = 0;
+    int i;
+
+    if (!region->mmaps) {
+        if (size) {
+            *size = MIN(data_size, region->size - data_offset);
+        }
+        return ptr;
+    }
+
+    for (i = 0; i < region->nr_mmaps; i++) {
+        VFIOMmap *map = region->mmaps + i;
+
+        if ((data_offset >= map->offset) &&
+            (data_offset < map->offset + map->size)) {
+
+            /* check if data_offset is within sparse mmap areas */
+            ptr = map->mmap + data_offset - map->offset;
+            if (size) {
+                *size = MIN(data_size, map->offset + map->size - data_offset);
+            }
+            break;
+        } else if ((data_offset < map->offset) &&
+                   (!limit || limit > map->offset)) {
+            /*
+             * data_offset is not within sparse mmap areas, find size of
+             * non-mapped area. Check through all list since region->mmaps list
+             * is not sorted.
+             */
+            limit = map->offset;
+        }
+    }
+
+    if (!ptr && size) {
+        *size = limit ? MIN(data_size, limit - data_offset) : data_size;
+    }
+    return ptr;
+}
+
+static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev, uint64_t *size)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    uint64_t data_offset = 0, data_size = 0, sz;
+    int ret;
+
+    ret = vfio_mig_read(vbasedev, &data_offset, sizeof(data_offset),
+                      region->fd_offset + VFIO_MIG_STRUCT_OFFSET(data_offset));
+    if (ret < 0) {
+        return ret;
+    }
+
+    ret = vfio_mig_read(vbasedev, &data_size, sizeof(data_size),
+                        region->fd_offset + VFIO_MIG_STRUCT_OFFSET(data_size));
+    if (ret < 0) {
+        return ret;
+    }
+
+    trace_vfio_save_buffer(vbasedev->name, data_offset, data_size,
+                           migration->pending_bytes);
+
+    qemu_put_be64(f, data_size);
+    sz = data_size;
+
+    while (sz) {
+        void *buf;
+        uint64_t sec_size;
+        bool buf_allocated = false;
+
+        buf = get_data_section_size(region, data_offset, sz, &sec_size);
+
+        if (!buf) {
+            buf = g_try_malloc(sec_size);
+            if (!buf) {
+                error_report("%s: Error allocating buffer ", __func__);
+                return -ENOMEM;
+            }
+            buf_allocated = true;
+
+            ret = vfio_mig_read(vbasedev, buf, sec_size,
+                                region->fd_offset + data_offset);
+            if (ret < 0) {
+                g_free(buf);
+                return ret;
+            }
+        }
+
+        qemu_put_buffer(f, buf, sec_size);
+
+        if (buf_allocated) {
+            g_free(buf);
+        }
+        sz -= sec_size;
+        data_offset += sec_size;
+    }
+
+    ret = qemu_file_get_error(f);
+
+    if (!ret && size) {
+        *size = data_size;
+    }
+
+    bytes_transferred += data_size;
+    return ret;
+}
+
+static int vfio_load_buffer(QEMUFile *f, VFIODevice *vbasedev,
+                            uint64_t data_size)
+{
+    VFIORegion *region = &vbasedev->migration->region;
+    uint64_t data_offset = 0, size, report_size;
+    int ret;
+
+    do {
+        ret = vfio_mig_read(vbasedev, &data_offset, sizeof(data_offset),
+                      region->fd_offset + VFIO_MIG_STRUCT_OFFSET(data_offset));
+        if (ret < 0) {
+            return ret;
+        }
+
+        if (data_offset + data_size > region->size) {
+            /*
+             * If data_size is greater than the data section of migration region
+             * then iterate the write buffer operation. This case can occur if
+             * size of migration region at destination is smaller than size of
+             * migration region at source.
+             */
+            report_size = size = region->size - data_offset;
+            data_size -= size;
+        } else {
+            report_size = size = data_size;
+            data_size = 0;
+        }
+
+        trace_vfio_load_state_device_data(vbasedev->name, data_offset, size);
+
+        while (size) {
+            void *buf;
+            uint64_t sec_size;
+            bool buf_alloc = false;
+
+            buf = get_data_section_size(region, data_offset, size, &sec_size);
+
+            if (!buf) {
+                buf = g_try_malloc(sec_size);
+                if (!buf) {
+                    error_report("%s: Error allocating buffer ", __func__);
+                    return -ENOMEM;
+                }
+                buf_alloc = true;
+            }
+
+            qemu_get_buffer(f, buf, sec_size);
+
+            if (buf_alloc) {
+                ret = vfio_mig_write(vbasedev, buf, sec_size,
+                        region->fd_offset + data_offset);
+                g_free(buf);
+
+                if (ret < 0) {
+                    return ret;
+                }
+            }
+            size -= sec_size;
+            data_offset += sec_size;
+        }
+
+        ret = vfio_mig_write(vbasedev, &report_size, sizeof(report_size),
+                        region->fd_offset + VFIO_MIG_STRUCT_OFFSET(data_size));
+        if (ret < 0) {
+            return ret;
+        }
+    } while (data_size);
+
+    return 0;
+}
+
+static int vfio_update_pending(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    uint64_t pending_bytes = 0;
+    int ret;
+
+    ret = vfio_mig_read(vbasedev, &pending_bytes, sizeof(pending_bytes),
+                    region->fd_offset + VFIO_MIG_STRUCT_OFFSET(pending_bytes));
+    if (ret < 0) {
+        migration->pending_bytes = 0;
+        return ret;
+    }
+
+    migration->pending_bytes = pending_bytes;
+    trace_vfio_update_pending(vbasedev->name, pending_bytes);
+    return 0;
+}
+
+static int vfio_save_device_config_state(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_CONFIG_STATE);
+
+    if (vbasedev->ops && vbasedev->ops->vfio_save_config) {
+        vbasedev->ops->vfio_save_config(vbasedev, f);
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    trace_vfio_save_device_config_state(vbasedev->name);
+
+    return qemu_file_get_error(f);
+}
+
+static int vfio_load_device_config_state(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    uint64_t data;
+
+    if (vbasedev->ops && vbasedev->ops->vfio_load_config) {
+        int ret;
+
+        ret = vbasedev->ops->vfio_load_config(vbasedev, f);
+        if (ret) {
+            error_report("%s: Failed to load device config space",
+                         vbasedev->name);
+            return ret;
+        }
+    }
+
+    data = qemu_get_be64(f);
+    if (data != VFIO_MIG_FLAG_END_OF_STATE) {
+        error_report("%s: Failed loading device config space, "
+                     "end flag incorrect 0x%"PRIx64, vbasedev->name, data);
+        return -EINVAL;
+    }
+
+    trace_vfio_load_device_config_state(vbasedev->name);
+    return qemu_file_get_error(f);
+}
+
+static void vfio_migration_cleanup(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+
+    if (migration->region.mmaps) {
+        vfio_region_unmap(&migration->region);
+    }
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int vfio_save_setup(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    int ret;
+
+    trace_vfio_save_setup(vbasedev->name);
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_SETUP_STATE);
+
+    if (migration->region.mmaps) {
+        /*
+         * Calling vfio_region_mmap() from migration thread. Memory API called
+         * from this function require locking the iothread when called from
+         * outside the main loop thread.
+         */
+        qemu_mutex_lock_iothread();
+        ret = vfio_region_mmap(&migration->region);
+        qemu_mutex_unlock_iothread();
+        if (ret) {
+            error_report("%s: Failed to mmap VFIO migration region: %s",
+                         vbasedev->name, strerror(-ret));
+            error_report("%s: Falling back to slow path", vbasedev->name);
+        }
+    }
+
+    ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_MASK,
+                                   VFIO_DEVICE_STATE_SAVING);
+    if (ret) {
+        error_report("%s: Failed to set state SAVING", vbasedev->name);
+        return ret;
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    return 0;
+}
+
+static void vfio_save_cleanup(void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+
+    vfio_migration_cleanup(vbasedev);
+    trace_vfio_save_cleanup(vbasedev->name);
+}
+
+static void vfio_save_pending(QEMUFile *f, void *opaque,
+                              uint64_t threshold_size,
+                              uint64_t *res_precopy_only,
+                              uint64_t *res_compatible,
+                              uint64_t *res_postcopy_only)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    int ret;
+
+    ret = vfio_update_pending(vbasedev);
+    if (ret) {
+        return;
+    }
+
+    *res_precopy_only += migration->pending_bytes;
+
+    trace_vfio_save_pending(vbasedev->name, *res_precopy_only,
+                            *res_postcopy_only, *res_compatible);
+}
+
+static int vfio_save_iterate(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    uint64_t data_size;
+    int ret;
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
+
+    if (migration->pending_bytes == 0) {
+        ret = vfio_update_pending(vbasedev);
+        if (ret) {
+            return ret;
+        }
+
+        if (migration->pending_bytes == 0) {
+            qemu_put_be64(f, 0);
+            qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+            /* indicates data finished, goto complete phase */
+            return 1;
+        }
+    }
+
+    ret = vfio_save_buffer(f, vbasedev, &data_size);
+    if (ret) {
+        error_report("%s: vfio_save_buffer failed %s", vbasedev->name,
+                     strerror(errno));
+        return ret;
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    /*
+     * Reset pending_bytes as .save_live_pending is not called during savevm or
+     * snapshot case, in such case vfio_update_pending() at the start of this
+     * function updates pending_bytes.
+     */
+    migration->pending_bytes = 0;
+    trace_vfio_save_iterate(vbasedev->name, data_size);
+    return 0;
+}
+
+static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    uint64_t data_size;
+    int ret;
+
+    ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_RUNNING,
+                                   VFIO_DEVICE_STATE_SAVING);
+    if (ret) {
+        error_report("%s: Failed to set state STOP and SAVING",
+                     vbasedev->name);
+        return ret;
+    }
+
+    ret = vfio_update_pending(vbasedev);
+    if (ret) {
+        return ret;
+    }
+
+    while (migration->pending_bytes > 0) {
+        qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
+        ret = vfio_save_buffer(f, vbasedev, &data_size);
+        if (ret < 0) {
+            error_report("%s: Failed to save buffer", vbasedev->name);
+            return ret;
+        }
+
+        if (data_size == 0) {
+            break;
+        }
+
+        ret = vfio_update_pending(vbasedev);
+        if (ret) {
+            return ret;
+        }
+    }
+
+    qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
+
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
+    }
+
+    ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_SAVING, 0);
+    if (ret) {
+        error_report("%s: Failed to set state STOPPED", vbasedev->name);
+        return ret;
+    }
+
+    trace_vfio_save_complete_precopy(vbasedev->name);
+    return ret;
+}
+
+static void vfio_save_state(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    int ret;
+
+    ret = vfio_save_device_config_state(f, opaque);
+    if (ret) {
+        error_report("%s: Failed to save device config space",
+                     vbasedev->name);
+        qemu_file_set_error(f, ret);
+    }
+}
+
+static int vfio_load_setup(QEMUFile *f, void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    int ret = 0;
+
+    if (migration->region.mmaps) {
+        ret = vfio_region_mmap(&migration->region);
+        if (ret) {
+            error_report("%s: Failed to mmap VFIO migration region %d: %s",
+                         vbasedev->name, migration->region.nr,
+                         strerror(-ret));
+            error_report("%s: Falling back to slow path", vbasedev->name);
+        }
+    }
+
+    ret = vfio_migration_set_state(vbasedev, ~VFIO_DEVICE_STATE_MASK,
+                                   VFIO_DEVICE_STATE_RESUMING);
+    if (ret) {
+        error_report("%s: Failed to set state RESUMING", vbasedev->name);
+        if (migration->region.mmaps) {
+            vfio_region_unmap(&migration->region);
+        }
+    }
+    return ret;
+}
+
+static int vfio_load_cleanup(void *opaque)
+{
+    VFIODevice *vbasedev = opaque;
+
+    vfio_migration_cleanup(vbasedev);
+    trace_vfio_load_cleanup(vbasedev->name);
+    return 0;
+}
+
+static int vfio_load_state(QEMUFile *f, void *opaque, int version_id)
+{
+    VFIODevice *vbasedev = opaque;
+    int ret = 0;
+    uint64_t data;
+
+    data = qemu_get_be64(f);
+    while (data != VFIO_MIG_FLAG_END_OF_STATE) {
+
+        trace_vfio_load_state(vbasedev->name, data);
+
+        switch (data) {
+        case VFIO_MIG_FLAG_DEV_CONFIG_STATE:
+        {
+            return vfio_load_device_config_state(f, opaque);
+        }
+        case VFIO_MIG_FLAG_DEV_SETUP_STATE:
+        {
+            data = qemu_get_be64(f);
+            if (data == VFIO_MIG_FLAG_END_OF_STATE) {
+                return ret;
+            } else {
+                error_report("%s: SETUP STATE: EOS not found 0x%"PRIx64,
+                             vbasedev->name, data);
+                return -EINVAL;
+            }
+            break;
+        }
+        case VFIO_MIG_FLAG_DEV_DATA_STATE:
+        {
+            uint64_t data_size = qemu_get_be64(f);
+
+            if (data_size) {
+                ret = vfio_load_buffer(f, vbasedev, data_size);
+                if (ret < 0) {
+                    return ret;
+                }
+            }
+            break;
+        }
+        default:
+            error_report("%s: Unknown tag 0x%"PRIx64, vbasedev->name, data);
+            return -EINVAL;
+        }
+
+        data = qemu_get_be64(f);
+        ret = qemu_file_get_error(f);
+        if (ret) {
+            return ret;
+        }
+    }
+    return ret;
+}
+
+static SaveVMHandlers savevm_vfio_handlers = {
+    .save_setup = vfio_save_setup,
+    .save_cleanup = vfio_save_cleanup,
+    .save_live_pending = vfio_save_pending,
+    .save_live_iterate = vfio_save_iterate,
+    .save_live_complete_precopy = vfio_save_complete_precopy,
+    .save_state = vfio_save_state,
+    .load_setup = vfio_load_setup,
+    .load_cleanup = vfio_load_cleanup,
+    .load_state = vfio_load_state,
+};
+
+/* ---------------------------------------------------------------------- */
+
+static void vfio_vmstate_change(void *opaque, bool running, RunState state)
+{
+    VFIODevice *vbasedev = opaque;
+    VFIOMigration *migration = vbasedev->migration;
+    uint32_t value, mask;
+    int ret;
+
+    if (vbasedev->migration->vm_running == running) {
+        return;
+    }
+
+    if (running) {
+        /*
+         * Here device state can have one of _SAVING, _RESUMING or _STOP bit.
+         * Transition from _SAVING to _RUNNING can happen if there is migration
+         * failure, in that case clear _SAVING bit.
+         * Transition from _RESUMING to _RUNNING occurs during resuming
+         * phase, in that case clear _RESUMING bit.
+         * In both the above cases, set _RUNNING bit.
+         */
+        mask = ~VFIO_DEVICE_STATE_MASK;
+        value = VFIO_DEVICE_STATE_RUNNING;
+    } else {
+        /*
+         * Here device state could be either _RUNNING or _SAVING|_RUNNING. Reset
+         * _RUNNING bit
+         */
+        mask = ~VFIO_DEVICE_STATE_RUNNING;
+
+        /*
+         * When VM state transition to stop for savevm command, device should
+         * start saving data.
+         */
+        if (state == RUN_STATE_SAVE_VM) {
+            value = VFIO_DEVICE_STATE_SAVING;
+        } else {
+            value = 0;
+        }
+    }
+
+    ret = vfio_migration_set_state(vbasedev, mask, value);
+    if (ret) {
+        /*
+         * Migration should be aborted in this case, but vm_state_notify()
+         * currently does not support reporting failures.
+         */
+        error_report("%s: Failed to set device state 0x%x", vbasedev->name,
+                     (migration->device_state & mask) | value);
+        qemu_file_set_error(migrate_get_current()->to_dst_file, ret);
+    }
+    vbasedev->migration->vm_running = running;
+    trace_vfio_vmstate_change(vbasedev->name, running, RunState_str(state),
+            (migration->device_state & mask) | value);
+}
+
+static void vfio_migration_state_notifier(Notifier *notifier, void *data)
+{
+    MigrationState *s = data;
+    VFIOMigration *migration = container_of(notifier, VFIOMigration,
+                                            migration_state);
+    VFIODevice *vbasedev = migration->vbasedev;
+    int ret;
+
+    trace_vfio_migration_state_notifier(vbasedev->name,
+                                        MigrationStatus_str(s->state));
+
+    switch (s->state) {
+    case MIGRATION_STATUS_CANCELLING:
+    case MIGRATION_STATUS_CANCELLED:
+    case MIGRATION_STATUS_FAILED:
+        bytes_transferred = 0;
+        ret = vfio_migration_set_state(vbasedev,
+                      ~(VFIO_DEVICE_STATE_SAVING | VFIO_DEVICE_STATE_RESUMING),
+                      VFIO_DEVICE_STATE_RUNNING);
+        if (ret) {
+            error_report("%s: Failed to set state RUNNING", vbasedev->name);
+        }
+    }
+}
+
+static void vfio_migration_exit(VFIODevice *vbasedev)
+{
+    VFIOMigration *migration = vbasedev->migration;
+
+    vfio_region_exit(&migration->region);
+    vfio_region_finalize(&migration->region);
+    g_free(vbasedev->migration);
+    vbasedev->migration = NULL;
+}
+
+static int vfio_migration_init(VFIODevice *vbasedev,
+                               struct vfio_region_info *info)
+{
+    int ret;
+    Object *obj;
+    VFIOMigration *migration;
+    char id[256] = "";
+    g_autofree char *path = NULL, *oid = NULL;
+
+    if (!vbasedev->ops->vfio_get_object) {
+        return -EINVAL;
+    }
+
+    obj = vbasedev->ops->vfio_get_object(vbasedev);
+    if (!obj) {
+        return -EINVAL;
+    }
+
+    vbasedev->migration = g_new0(VFIOMigration, 1);
+
+    ret = vfio_region_setup(obj, vbasedev, &vbasedev->migration->region,
+                            info->index, "migration");
+    if (ret) {
+        error_report("%s: Failed to setup VFIO migration region %d: %s",
+                     vbasedev->name, info->index, strerror(-ret));
+        goto err;
+    }
+
+    if (!vbasedev->migration->region.size) {
+        error_report("%s: Invalid zero-sized VFIO migration region %d",
+                     vbasedev->name, info->index);
+        ret = -EINVAL;
+        goto err;
+    }
+
+    migration = vbasedev->migration;
+    migration->vbasedev = vbasedev;
+
+    oid = vmstate_if_get_id(VMSTATE_IF(DEVICE(obj)));
+    if (oid) {
+        path = g_strdup_printf("%s/vfio", oid);
+    } else {
+        path = g_strdup("vfio");
+    }
+    strpadcpy(id, sizeof(id), path, '\0');
+
+    register_savevm_live(id, VMSTATE_INSTANCE_ID_ANY, 1, &savevm_vfio_handlers,
+                         vbasedev);
+
+    migration->vm_state = qdev_add_vm_change_state_handler(vbasedev->dev,
+                                                           vfio_vmstate_change,
+                                                           vbasedev);
+    migration->migration_state.notify = vfio_migration_state_notifier;
+    add_migration_state_change_notifier(&migration->migration_state);
+    return 0;
+
+err:
+    vfio_migration_exit(vbasedev);
+    return ret;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int64_t vfio_mig_bytes_transferred(void)
+{
+    return bytes_transferred;
+}
+
+int vfio_migration_probe(VFIODevice *vbasedev, Error **errp)
+{
+    VFIOContainer *container = vbasedev->group->container;
+    struct vfio_region_info *info = NULL;
+    int ret = -ENOTSUP;
+
+    if (!vbasedev->enable_migration || !container->dirty_pages_supported) {
+        goto add_blocker;
+    }
+
+    ret = vfio_get_dev_region_info(vbasedev, VFIO_REGION_TYPE_MIGRATION,
+                                   VFIO_REGION_SUBTYPE_MIGRATION, &info);
+    if (ret) {
+        goto add_blocker;
+    }
+
+    ret = vfio_migration_init(vbasedev, info);
+    if (ret) {
+        goto add_blocker;
+    }
+
+    trace_vfio_migration_probe(vbasedev->name, info->index);
+    g_free(info);
+    return 0;
+
+add_blocker:
+    error_setg(&vbasedev->migration_blocker,
+               "VFIO device doesn't support migration");
+    g_free(info);
+
+    ret = migrate_add_blocker(vbasedev->migration_blocker, errp);
+    if (ret < 0) {
+        error_free(vbasedev->migration_blocker);
+        vbasedev->migration_blocker = NULL;
+    }
+    return ret;
+}
+
+void vfio_migration_finalize(VFIODevice *vbasedev)
+{
+    if (vbasedev->migration) {
+        VFIOMigration *migration = vbasedev->migration;
+
+        remove_migration_state_change_notifier(&migration->migration_state);
+        qemu_del_vm_change_state_handler(migration->vm_state);
+        unregister_savevm(VMSTATE_IF(vbasedev->dev), "vfio", vbasedev);
+        vfio_migration_exit(vbasedev);
+    }
+
+    if (vbasedev->migration_blocker) {
+        migrate_del_blocker(vbasedev->migration_blocker);
+        error_free(vbasedev->migration_blocker);
+        vbasedev->migration_blocker = NULL;
+    }
+}