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Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device
From: |
Yan Zhao |
Subject: |
Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device |
Date: |
Thu, 20 Jun 2019 20:25:18 -0400 |
User-agent: |
Mutt/1.9.4 (2018-02-28) |
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
>
- Re: [Qemu-devel] [PATCH v4 08/13] vfio: Add save state functions to SaveVMHandlers, (continued)
- [Qemu-devel] [PATCH v4 09/13] vfio: Add load state functions to SaveVMHandlers, Kirti Wankhede, 2019/06/20
- [Qemu-devel] [PATCH v4 10/13] vfio: Add function to get dirty page list, Kirti Wankhede, 2019/06/20
- [Qemu-devel] [PATCH v4 11/13] vfio: Add vfio_listerner_log_sync to mark dirty pages, Kirti Wankhede, 2019/06/20
- [Qemu-devel] [PATCH v4 12/13] vfio: Make vfio-pci device migration capable., Kirti Wankhede, 2019/06/20
- [Qemu-devel] [PATCH v4 13/13] vfio: Add trace events in migration code path, Kirti Wankhede, 2019/06/20
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device,
Yan Zhao <=
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Yan Zhao, 2019/06/20
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Kirti Wankhede, 2019/06/21
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Yan Zhao, 2019/06/21
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Kirti Wankhede, 2019/06/21
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Yan Zhao, 2019/06/21
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Dr. David Alan Gilbert, 2019/06/24
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Yan Zhao, 2019/06/25
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Dr. David Alan Gilbert, 2019/06/28
- Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device, Yan Zhao, 2019/06/28