From: Yan Zhao <yan.y.zhao@intel.com>
To: Kirti Wankhede <kwankhede@nvidia.com>
Cc: "Zhengxiao.zx@Alibaba-inc.com" <Zhengxiao.zx@Alibaba-inc.com>,
"Tian, Kevin" <kevin.tian@intel.com>,
"Liu, Yi L" <yi.l.liu@intel.com>,
"cjia@nvidia.com" <cjia@nvidia.com>,
"eskultet@redhat.com" <eskultet@redhat.com>,
"Yang, Ziye" <ziye.yang@intel.com>,
"yulei.zhang@intel.com" <yulei.zhang@intel.com>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"shuangtai.tst@alibaba-inc.com" <shuangtai.tst@alibaba-inc.com>,
"dgilbert@redhat.com" <dgilbert@redhat.com>,
"Wang, Zhi A" <zhi.a.wang@intel.com>,
"mlevitsk@redhat.com" <mlevitsk@redhat.com>,
"pasic@linux.ibm.com" <pasic@linux.ibm.com>,
"aik@ozlabs.ru" <aik@ozlabs.ru>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"eauger@redhat.com" <eauger@redhat.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"felipe@nutanix.com" <felipe@nutanix.com>,
"jonathan.davies@nutanix.com" <jonathan.davies@nutanix.com>,
"Liu, Changpeng" <changpeng.liu@intel.com>,
"Ken.Xue@amd.com" <Ken.Xue@amd.com>
Subject: Re: [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device
Date: Thu, 20 Jun 2019 21:24:05 -0400 [thread overview]
Message-ID: <20190621012404.GA4173@joy-OptiPlex-7040> (raw)
In-Reply-To: <20190621002518.GF9303@joy-OptiPlex-7040>
On Fri, Jun 21, 2019 at 08:25:18AM +0800, Yan Zhao wrote:
> 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 start in target vm.
>
hi
to better describe this idea:
in pre-copy only case, the flow is
start migration --> .save_live_iterate (several round) -> stop source vm
--> .save_live_complete_precopy --> .pre_save -->start target vm
-->migration complete
in post-copy enabled case, the flow is
start migration --> .save_live_iterate (several round) --> start post copy -->
stop source vm --> .pre_save --> start target vm --> .save_live_iterate (several round)
-->migration complete
Therefore, we should put saving of device state in .pre_save interface
rather than in .save_live_complete_precopy.
The device state includes pci config data, page tables, register state, etc.
The .save_live_iterate and .save_live_complete_precopy should only deal
with saving dirty memory.
I know current implementation does not support post-copy. but at least
it should not require huge change when we decide to enable it in future.
Thanks
Yan
> > |
> > (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
> >
next prev parent reply other threads:[~2019-06-21 1:31 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 14:37 [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 01/13] vfio: KABI for migration interface Kirti Wankhede
2019-06-20 17:18 ` Alex Williamson
2019-06-21 5:52 ` Kirti Wankhede
2019-06-21 15:03 ` Alex Williamson
2019-06-21 19:35 ` Kirti Wankhede
2019-06-21 20:00 ` Alex Williamson
2019-06-21 20:30 ` Kirti Wankhede
2019-06-21 22:01 ` Alex Williamson
2019-06-24 15:00 ` Kirti Wankhede
2019-06-24 15:25 ` Alex Williamson
2019-06-24 18:52 ` Kirti Wankhede
2019-06-24 19:01 ` Alex Williamson
2019-06-25 15:20 ` Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 02/13] vfio: Add function to unmap VFIO region Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 03/13] vfio: Add save and load functions for VFIO PCI devices Kirti Wankhede
2019-06-21 0:12 ` Yan Zhao
2019-06-21 6:44 ` Kirti Wankhede
2019-06-21 7:50 ` Yan Zhao
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 04/13] vfio: Add migration region initialization and finalize function Kirti Wankhede
2019-06-24 14:00 ` Cornelia Huck
2019-06-27 14:56 ` Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 05/13] vfio: Add VM state change handler to know state of VM Kirti Wankhede
2019-06-25 10:29 ` Dr. David Alan Gilbert
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 06/13] vfio: Add migration state change notifier Kirti Wankhede
2019-06-27 10:33 ` Dr. David Alan Gilbert
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 07/13] vfio: Register SaveVMHandlers for VFIO device Kirti Wankhede
2019-06-27 10:01 ` Dr. David Alan Gilbert
2019-06-27 14:31 ` Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 08/13] vfio: Add save state functions to SaveVMHandlers Kirti Wankhede
2019-06-20 19:25 ` Alex Williamson
2019-06-21 6:38 ` Kirti Wankhede
2019-06-21 15:16 ` Alex Williamson
2019-06-21 19:38 ` Kirti Wankhede
2019-06-21 20:02 ` Alex Williamson
2019-06-21 20:07 ` Kirti Wankhede
2019-06-21 20:32 ` Alex Williamson
2019-06-21 21:05 ` Kirti Wankhede
2019-06-21 22:13 ` Alex Williamson
2019-06-24 14:31 ` Kirti Wankhede
2019-06-21 0:31 ` Yan Zhao
2019-06-25 3:30 ` Yan Zhao
2019-06-28 8:50 ` Dr. David Alan Gilbert
2019-06-28 21:16 ` Yan Zhao
2019-06-28 9:09 ` Dr. David Alan Gilbert
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 09/13] vfio: Add load " Kirti Wankhede
2019-06-28 9:18 ` Dr. David Alan Gilbert
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 10/13] vfio: Add function to get dirty page list Kirti Wankhede
2019-06-26 0:40 ` Yan Zhao
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 11/13] vfio: Add vfio_listerner_log_sync to mark dirty pages Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 12/13] vfio: Make vfio-pci device migration capable Kirti Wankhede
2019-06-20 14:37 ` [Qemu-devel] [PATCH v4 13/13] vfio: Add trace events in migration code path Kirti Wankhede
2019-06-20 18:50 ` Dr. David Alan Gilbert
2019-06-21 5:54 ` Kirti Wankhede
2019-06-21 0:25 ` [Qemu-devel] [PATCH v4 00/13] Add migration support for VFIO device Yan Zhao
2019-06-21 1:24 ` Yan Zhao [this message]
2019-06-21 8:02 ` Kirti Wankhede
2019-06-21 8:46 ` Yan Zhao
2019-06-21 9:22 ` Kirti Wankhede
2019-06-21 10:45 ` Yan Zhao
2019-06-24 19:00 ` Dr. David Alan Gilbert
2019-06-26 0:43 ` Yan Zhao
2019-06-28 9:44 ` Dr. David Alan Gilbert
2019-06-28 21:28 ` Yan Zhao
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