On Thu, Jun 20, 2019 at 10:37:28PM +0800, Kirti Wankhede wrote: > Add migration support for VFIO device > > This Patch set include patches as below: > - Define KABI for VFIO device for migration support. > - Added save and restore functions for PCI configuration space > - Generic migration functionality for VFIO device. > * This patch set adds functionality only for PCI devices, but can be > extended to other VFIO devices. > * Added all the basic functions required for pre-copy, stop-and-copy and > resume phases of migration. > * Added state change notifier and from that notifier function, VFIO > device's state changed is conveyed to VFIO device driver. > * During save setup phase and resume/load setup phase, migration region > is queried and is used to read/write VFIO device data. > * .save_live_pending and .save_live_iterate are implemented to use QEMU's > functionality of iteration during pre-copy phase. > * In .save_live_complete_precopy, that is in stop-and-copy phase, > iteration to read data from VFIO device driver is implemented till pending > bytes returned by driver are not zero. > * Added function to get dirty pages bitmap for the pages which are used by > driver. > - Add vfio_listerner_log_sync to mark dirty pages. > - Make VFIO PCI device migration capable. If migration region is not provided > by > driver, migration is blocked. > > Below is the flow of state change for live migration where states in brackets > represent VM state, migration state and VFIO device state as: > (VM state, MIGRATION_STATUS, VFIO_DEVICE_STATE) > > Live migration save path: > QEMU normal running state > (RUNNING, _NONE, _RUNNING) > | > migrate_init spawns migration_thread. > (RUNNING, _SETUP, _RUNNING|_SAVING) > Migration thread then calls each device's .save_setup() > | > (RUNNING, _ACTIVE, _RUNNING|_SAVING) > If device is active, get pending bytes by .save_live_pending() > if pending bytes >= threshold_size, call save_live_iterate() > Data of VFIO device for pre-copy phase is copied. > Iterate till pending bytes converge and are less than threshold > | > On migration completion, vCPUs stops and calls .save_live_complete_precopy > for each active device. VFIO device is then transitioned in > _SAVING state. > (FINISH_MIGRATE, _DEVICE, _SAVING) > For VFIO device, iterate in .save_live_complete_precopy until > pending data is 0. > (FINISH_MIGRATE, _DEVICE, _STOPPED)
I suggest we also register to VMStateDescription, whose .pre_save handler would get called after .save_live_complete_precopy in pre-copy only case, and will called before .save_live_iterate in post-copy enabled case. In the .pre_save handler, we can save all device state which must be copied after device stop in source vm and before device state in target vm. > | > (FINISH_MIGRATE, _COMPLETED, STOPPED) > Migraton thread schedule cleanup bottom half and exit > > Live migration resume path: > Incomming migration calls .load_setup for each device > (RESTORE_VM, _ACTIVE, STOPPED) > | > For each device, .load_state is called for that device section data > | > At the end, called .load_cleanup for each device and vCPUs are started. > | > (RUNNING, _NONE, _RUNNING) > > Note that: > - Migration post copy is not supported. > > v3 -> v4: > - Added one more bit for _RESUMING flag to be set explicitly. > - data_offset field is read-only for user space application. > - data_size is read for every iteration before reading data from migration, > that > is removed assumption that data will be till end of migration region. > - If vendor driver supports mappable sparsed region, map those region during > setup state of save/load, similarly unmap those from cleanup routines. > - Handles race condition that causes data corruption in migration region > during > save device state by adding mutex and serialiaing save_buffer and > get_dirty_pages routines. > - Skip called get_dirty_pages routine for mapped MMIO region of device. > - Added trace events. > - Splitted into multiple functional patches. > > v2 -> v3: > - Removed enum of VFIO device states. Defined VFIO device state with 2 bits. > - Re-structured vfio_device_migration_info to keep it minimal and defined > action > on read and write access on its members. > > v1 -> v2: > - Defined MIGRATION region type and sub-type which should be used with region > type capability. > - Re-structured vfio_device_migration_info. This structure will be placed at > 0th > offset of migration region. > - Replaced ioctl with read/write for trapped part of migration region. > - Added both type of access support, trapped or mmapped, for data section of > the > region. > - Moved PCI device functions to pci file. > - Added iteration to get dirty page bitmap until bitmap for all requested > pages > are copied. > > Thanks, > Kirti > > > Kirti Wankhede (13): > vfio: KABI for migration interface > vfio: Add function to unmap VFIO region > vfio: Add save and load functions for VFIO PCI devices > vfio: Add migration region initialization and finalize function > vfio: Add VM state change handler to know state of VM > vfio: Add migration state change notifier > vfio: Register SaveVMHandlers for VFIO device > vfio: Add save state functions to SaveVMHandlers > vfio: Add load state functions to SaveVMHandlers > vfio: Add function to get dirty page list > vfio: Add vfio_listerner_log_sync to mark dirty pages > vfio: Make vfio-pci device migration capable. > vfio: Add trace events in migration code path > > hw/vfio/Makefile.objs | 2 +- > hw/vfio/common.c | 55 +++ > hw/vfio/migration.c | 815 > ++++++++++++++++++++++++++++++++++++++++++ > hw/vfio/pci.c | 126 ++++++- > hw/vfio/pci.h | 29 ++ > hw/vfio/trace-events | 19 + > include/hw/vfio/vfio-common.h | 22 ++ > linux-headers/linux/vfio.h | 71 ++++ > 8 files changed, 1132 insertions(+), 7 deletions(-) > create mode 100644 hw/vfio/migration.c > > -- > 2.7.0 >
