On Fri, Jul 12, 2019 at 12:23:15AM +0800, Dr. David Alan Gilbert wrote: > * Yan Zhao (yan.y.z...@intel.com) wrote: > > On Thu, Jul 11, 2019 at 06:50:12PM +0800, Dr. David Alan Gilbert wrote: > > > * Yan Zhao (yan.y.z...@intel.com) wrote: > > > > Hi Kirti, > > > > There are still unaddressed comments to your patches v4. > > > > Would you mind addressing them? > > > > > > > > 1. should we register two migration interfaces simultaneously > > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04750.html) > > > > > > Please don't do this. > > > As far as I'm aware we currently only have one device that does that > > > (vmxnet3) and a patch has just been posted that fixes/removes that. > > > > > > Dave > > > > > hi Dave, > > Thanks for notifying this. but if we want to support postcopy in future, > > after device stops, what interface could we use to transfer data of > > device state only? > > for postcopy, when source device stops, we need to transfer only > > necessary device state to target vm before target vm starts, and we > > don't want to transfer device memory as we'll do that after target vm > > resuming. > > Hmm ok, lets see; that's got to happen in the call to: > qemu_savevm_state_complete_precopy(fb, false, false); > that's made from postcopy_start. > (the false's are iterable_only and inactivate_disks) > > and at that time I believe the state is POSTCOPY_ACTIVE, so in_postcopy > is true. > > If you're doing postcopy, then you'll probably define a has_postcopy() > function, so qemu_savevm_state_complete_precopy will skip the > save_live_complete_precopy call from it's loop for at least two of the > reasons in it's big if. > > So you're right; you need the VMSD for this to happen in the second > loop in qemu_savevm_state_complete_precopy. Hmm. > > Now, what worries me, and I don't know the answer, is how the section > header for the vmstate and the section header for an iteration look > on the stream; how are they different? > may we name one "vfio" and the other "vfio-vmsd", and let iteration interface for device memory data and vmstate interface for device state data?
Thanks Yan > Dave > > > Thanks > > Yan > > > > > > 2. in each save iteration, how much data is to be saved > > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04683.html) > > > > 3. do we need extra interface to get data for device state only > > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg04812.html) > > > > 4. definition of dirty page copied_pfn > > > > (https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg05592.html) > > > > > > > > Also, I'm glad to see that you updated code by following my comments > > > > below, > > > > but please don't forget to reply my comments next time:) > > > > https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg05357.html > > > > https://lists.gnu.org/archive/html/qemu-devel/2019-06/msg06454.html > > > > > > > > Thanks > > > > Yan > > > > > > > > On Tue, Jul 09, 2019 at 05:49:07PM +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) > > > > > | > > > > > (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. > > > > > > > > > > v6 -> v7: > > > > > - Fix build failures. > > > > > > > > > > v5 -> v6: > > > > > - Fix build failure. > > > > > > > > > > v4 -> v5: > > > > > - Added decriptive comment about the sequence of access of members of > > > > > structure > > > > > vfio_device_migration_info to be followed based on Alex's suggestion > > > > > - Updated get dirty pages sequence. > > > > > - As per Cornelia Huck's suggestion, added callbacks to VFIODeviceOps > > > > > to > > > > > get_object, save_config and load_config. > > > > > - Fixed multiple nit picks. > > > > > - Tested live migration with multiple vfio device assigned to a VM. > > > > > > > > > > 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 vfio_get_object callback to VFIODeviceOps > > > > > 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. > > > > > > > > > > hw/vfio/Makefile.objs | 2 +- > > > > > hw/vfio/common.c | 55 +++ > > > > > hw/vfio/migration.c | 874 > > > > > ++++++++++++++++++++++++++++++++++++++++++ > > > > > hw/vfio/pci.c | 137 ++++++- > > > > > hw/vfio/trace-events | 19 + > > > > > include/hw/vfio/vfio-common.h | 25 ++ > > > > > linux-headers/linux/vfio.h | 166 ++++++++ > > > > > 7 files changed, 1271 insertions(+), 7 deletions(-) > > > > > create mode 100644 hw/vfio/migration.c > > > > > > > > > > -- > > > > > 2.7.0 > > > > > > > > -- > > > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
