On Fri, Jun 28, 2019 at 04:50:30PM +0800, Dr. David Alan Gilbert wrote:
> * Yan Zhao (yan.y.z...@intel.com) wrote:
> > On Fri, Jun 21, 2019 at 08:31:53AM +0800, Yan Zhao wrote:
> > > 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;
> > > > + }
> > by definition,
> > - res_precopy_only is for data which must be migrated in precopy phase
> > or in stopped state, in other words - before target vm start
> > - res_postcopy_only is for data which must be migrated in postcopy phase
> > or in stopped state, in other words - after source vm stop
> > So, we can only determining data type by the nature of the data. i.e.
> > if it is device state data which must be copied after source vm stop and
> > before target vm start, it belongs to res_precopy_only.
> >
> > It is not right to determining data type by current device state.
>
> Right; you can determine it by whether postcopy is *enabled* or not.
> However, since this isn't ready for postcopy yet anyway, just add it to
> res_postcopy_only all the time; then you can come back to postcopy
hi Dave,
do you mean "add it to res_precopy_only all the time" here?
Thanks
Yan
> later.
>
> Dave
>
> > Thanks
> > Yan
> >
> > > > + *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
> > > >
> > >
> --
> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
