On Thu, Jun 20, 2019 at 10:37:36PM +0800, Kirti Wankhede wrote:
> Added .save_live_pending, .save_live_iterate and .save_live_complete_precopy
> functions. These functions handles pre-copy and stop-and-copy phase.
>
> In _SAVING|_RUNNING device state or pre-copy phase:
> - read pending_bytes
> - read data_offset - indicates kernel driver to write data to staging
> buffer which is mmapped.
> - read data_size - amount of data in bytes written by vendor driver in
> migration
> region.
> - if data section is trapped, pread() number of bytes in data_size, from
> data_offset.
> - if data section is mmaped, read mmaped buffer of size data_size.
> - Write data packet to file stream as below:
> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data,
> VFIO_MIG_FLAG_END_OF_STATE }
>
> In _SAVING device state or stop-and-copy phase
> a. read config space of device and save to migration file stream. This
> doesn't need to be from vendor driver. Any other special config state
> from driver can be saved as data in following iteration.
> b. read pending_bytes - indicates kernel driver to write data to staging
> buffer which is mmapped.
> c. read data_size - amount of data in bytes written by vendor driver in
> migration region.
> d. if data section is trapped, pread() from data_offset of size data_size.
> e. if data section is mmaped, read mmaped buffer of size data_size.
> f. Write data packet as below:
> {VFIO_MIG_FLAG_DEV_DATA_STATE, data_size, actual data}
> g. iterate through steps b to f until (pending_bytes > 0)
> h. Write {VFIO_MIG_FLAG_END_OF_STATE}
>
> .save_live_iterate runs outside the iothread lock in the migration case, which
> could race with asynchronous call to get dirty page list causing data
> corruption
> in mapped migration region. Mutex added here to serial migration buffer read
> operation.
>
> Signed-off-by: Kirti Wankhede <kwankh...@nvidia.com>
> Reviewed-by: Neo Jia <c...@nvidia.com>
> ---
> hw/vfio/migration.c | 212
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 212 insertions(+)
>
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index fe0887c27664..0a2f30872316 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -107,6 +107,111 @@ static int vfio_migration_set_state(VFIODevice
> *vbasedev, uint32_t state)
> return 0;
> }
>
> +static int vfio_save_buffer(QEMUFile *f, VFIODevice *vbasedev)
> +{
> + VFIOMigration *migration = vbasedev->migration;
> + VFIORegion *region = &migration->region.buffer;
> + uint64_t data_offset = 0, data_size = 0;
> + int ret;
> +
> + ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset),
> + region->fd_offset + offsetof(struct
> vfio_device_migration_info,
> + data_offset));
> + if (ret != sizeof(data_offset)) {
> + error_report("Failed to get migration buffer data offset %d",
> + ret);
> + return -EINVAL;
> + }
> +
> + ret = pread(vbasedev->fd, &data_size, sizeof(data_size),
> + region->fd_offset + offsetof(struct
> vfio_device_migration_info,
> + data_size));
> + if (ret != sizeof(data_size)) {
> + error_report("Failed to get migration buffer data size %d",
> + ret);
> + return -EINVAL;
> + }
> +
how big is the data_size ?
if this size is too big, it may take too much time and block others.
> + if (data_size > 0) {
> + void *buf = NULL;
> + bool buffer_mmaped = false;
> +
> + if (region->mmaps) {
> + int i;
> +
> + for (i = 0; i < region->nr_mmaps; i++) {
> + if ((data_offset >= region->mmaps[i].offset) &&
> + (data_offset < region->mmaps[i].offset +
> + region->mmaps[i].size)) {
> + buf = region->mmaps[i].mmap + (data_offset -
> + region->mmaps[i].offset);
> + buffer_mmaped = true;
> + break;
> + }
> + }
> + }
> +
> + if (!buffer_mmaped) {
> + buf = g_malloc0(data_size);
> + ret = pread(vbasedev->fd, buf, data_size,
> + region->fd_offset + data_offset);
> + if (ret != data_size) {
> + error_report("Failed to get migration data %d", ret);
> + g_free(buf);
> + return -EINVAL;
> + }
> + }
> +
> + qemu_put_be64(f, data_size);
> + qemu_put_buffer(f, buf, data_size);
> +
> + if (!buffer_mmaped) {
> + g_free(buf);
> + }
> + migration->pending_bytes -= data_size;
> + } else {
> + qemu_put_be64(f, data_size);
> + }
> +
> + ret = qemu_file_get_error(f);
> +
> + return data_size;
> +}
> +
> +static int vfio_update_pending(VFIODevice *vbasedev)
> +{
> + VFIOMigration *migration = vbasedev->migration;
> + VFIORegion *region = &migration->region.buffer;
> + uint64_t pending_bytes = 0;
> + int ret;
> +
> + ret = pread(vbasedev->fd, &pending_bytes, sizeof(pending_bytes),
> + region->fd_offset + offsetof(struct
> vfio_device_migration_info,
> + pending_bytes));
> + if ((ret < 0) || (ret != sizeof(pending_bytes))) {
> + error_report("Failed to get pending bytes %d", ret);
> + migration->pending_bytes = 0;
> + return (ret < 0) ? ret : -EINVAL;
> + }
> +
> + migration->pending_bytes = 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->type == VFIO_DEVICE_TYPE_PCI) {
> + vfio_pci_save_config(vbasedev, f);
> + }
> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
> +
> + return qemu_file_get_error(f);
> +}
> +
> /* ---------------------------------------------------------------------- */
>
> static int vfio_save_setup(QEMUFile *f, void *opaque)
> @@ -163,9 +268,116 @@ static void vfio_save_cleanup(void *opaque)
> }
> }
>
> +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;
> + }
> +
> + if (vbasedev->device_state & VFIO_DEVICE_STATE_RUNNING) {
> + *res_precopy_only += migration->pending_bytes;
> + } else {
> + *res_postcopy_only += migration->pending_bytes;
> + }
> + *res_compatible += 0;
> +}
> +
> +static int vfio_save_iterate(QEMUFile *f, void *opaque)
> +{
> + VFIODevice *vbasedev = opaque;
> + VFIOMigration *migration = vbasedev->migration;
> + int ret;
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
> +
> + qemu_mutex_lock(&migration->lock);
> + ret = vfio_save_buffer(f, vbasedev);
> + qemu_mutex_unlock(&migration->lock);
> +
> + if (ret < 0) {
> + error_report("vfio_save_buffer failed %s",
> + strerror(errno));
> + return ret;
> + }
> +
> + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);
> +
> + ret = qemu_file_get_error(f);
> + if (ret) {
> + return ret;
> + }
> +
> + return ret;
> +}
> +
> +static int vfio_save_complete_precopy(QEMUFile *f, void *opaque)
> +{
> + VFIODevice *vbasedev = opaque;
> + VFIOMigration *migration = vbasedev->migration;
> + int ret;
> +
> + ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_SAVING);
> + if (ret) {
> + error_report("Failed to set state STOP and SAVING");
> + return ret;
> + }
> +
> + ret = vfio_save_device_config_state(f, opaque);
> + if (ret) {
> + 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);
> + if (ret < 0) {
> + error_report("Failed to save buffer");
> + return ret;
> + } else if (ret == 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_STOPPED);
> + if (ret) {
> + error_report("Failed to set state STOPPED");
> + 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,
> };
>
> /* ---------------------------------------------------------------------- */
> --
> 2.7.0
>
