| Message ID | 1603449643-12851-1-git-send-email-kwankhede@nvidia.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add migration support for VFIO devices | expand |
Hi Kirti, On 10/23/20 12:40 PM, Kirti Wankhede wrote: > Hi, > > This Patch set adds migration support for VFIO devices in QEMU. ... > Since there is no device which has hardware support for system memmory > dirty bitmap tracking, right now there is no other API from vendor driver > to VFIO IOMMU module to report dirty pages. In future, when such hardware > support will be implemented, an API will be required in kernel such that > vendor driver could report dirty pages to VFIO module during migration phases. > > 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 total 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 > (RESTORE_VM, _ACTIVE, _RESUMING) > | > At the end, called .load_cleanup for each device and vCPUs are started. > | > (RUNNING, _NONE, _RUNNING) > > Note that: > - Migration post copy is not supported. Can you commit this ^^^ somewhere in docs/devel/ please? (as a patch on top of this series)
On 10/24/2020 10:26 PM, Philippe Mathieu-Daudé wrote: > Hi Kirti, > > On 10/23/20 12:40 PM, Kirti Wankhede wrote: >> Hi, >> >> This Patch set adds migration support for VFIO devices in QEMU. > ... > >> Since there is no device which has hardware support for system memmory >> dirty bitmap tracking, right now there is no other API from vendor driver >> to VFIO IOMMU module to report dirty pages. In future, when such hardware >> support will be implemented, an API will be required in kernel such that >> vendor driver could report dirty pages to VFIO module during migration >> phases. >> >> 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 total 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 >> (RESTORE_VM, _ACTIVE, _RESUMING) >> | >> At the end, called .load_cleanup for each device and vCPUs are >> started. >> | >> (RUNNING, _NONE, _RUNNING) >> >> Note that: >> - Migration post copy is not supported. > > Can you commit this ^^^ somewhere in docs/devel/ please? > (as a patch on top of this series) > Philippe, Alex, I'm going to respin this series with r-bs and fix suggested by Yan. Should this doc be part of this series or we can add it later after 10/27 if again review of this doc would need some iterations? Thanks, Kirti
On 10/24/20 7:48 PM, Kirti Wankhede wrote: > On 10/24/2020 10:26 PM, Philippe Mathieu-Daudé wrote: >> Hi Kirti, >> >> On 10/23/20 12:40 PM, Kirti Wankhede wrote: >>> Hi, >>> >>> This Patch set adds migration support for VFIO devices in QEMU. >> ... >> >>> Since there is no device which has hardware support for system memmory >>> dirty bitmap tracking, right now there is no other API from vendor >>> driver >>> to VFIO IOMMU module to report dirty pages. In future, when such >>> hardware >>> support will be implemented, an API will be required in kernel such that >>> vendor driver could report dirty pages to VFIO module during >>> migration phases. >>> >>> 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 total 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 >>> (RESTORE_VM, _ACTIVE, _RESUMING) >>> | >>> At the end, called .load_cleanup for each device and vCPUs are >>> started. >>> | >>> (RUNNING, _NONE, _RUNNING) >>> >>> Note that: >>> - Migration post copy is not supported. >> >> Can you commit this ^^^ somewhere in docs/devel/ please? >> (as a patch on top of this series) >> > > Philippe, Alex, > I'm going to respin this series with r-bs and fix suggested by Yan. > Should this doc be part of this series or we can add it later after > 10/27 if again review of this doc would need some iterations? I suppose it is up to the maintainer, no objection from my part. This information seems valuable and wouldn't like it be lost. If by 10/27 you refer to the "soft freeze", then there is no problem to add documentation patches after this date :) Regards, Phil.
Hi, This Patch set adds migration support for VFIO devices in QEMU. This Patch set include patches as below: Patch 1-2: - Few code refactor Patch 3: - Added save and restore functions for PCI configuration space. Used pci_device_save() and pci_device_load() so that config space cache is saved and restored. Patch 4-9: - Generic migration functionality for VFIO device. * This patch set adds functionality 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 zero. Patch 10 - Set DIRTY_MEMORY_MIGRATION flag in dirty log mask for migration with vIOMMU enabled. Patch 11: - Get migration capability from kernel module. Patch 12-13: - Add function to start and stop dirty pages tracking. - Add vfio_listerner_log_sync to mark dirty pages. Dirty pages bitmap is queried per container. All pages pinned by vendor driver through vfio_pin_pages external API has to be marked as dirty during migration. When there are CPU writes, CPU dirty page tracking can identify dirtied pages, but any page pinned by vendor driver can also be written by device. As of now there is no device which has hardware support for dirty page tracking. So all pages which are pinned by vendor driver should be considered as dirty. In Qemu, marking pages dirty is only done when device is in stop-and-copy phase because if pages are marked dirty during pre-copy phase and content is transfered from source to distination, there is no way to know newly dirtied pages from the point they were copied earlier until device stops. To avoid repeated copy of same content, pinned pages are marked dirty only during stop-and-copy phase. Patch 14: When vIOMMU is enabled, used IOMMU notifier to get call back for mapped pages on replay during stop-and-copy phase. Patch 15: - With vIOMMU, IO virtual address range can get unmapped while in pre-copy phase of migration. In that case, unmap ioctl should return pages pinned in that range and QEMU should report corresponding guest physical pages dirty. Patch 16: - Make VFIO PCI device migration capable. If migration region is not provided by driver, migration is blocked. Patch 17: - Added VFIO device stats to MigrationInfo Yet TODO: Since there is no device which has hardware support for system memmory dirty bitmap tracking, right now there is no other API from vendor driver to VFIO IOMMU module to report dirty pages. In future, when such hardware support will be implemented, an API will be required in kernel such that vendor driver could report dirty pages to VFIO module during migration phases. 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 total 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 (RESTORE_VM, _ACTIVE, _RESUMING) | At the end, called .load_cleanup for each device and vCPUs are started. | (RUNNING, _NONE, _RUNNING) Note that: - Migration post copy is not supported. v27 -> 28 - Nit picks and minor changes suggested by Alex. v26 -> 27 - Major change in Patch 3 -PCI config space save and long using VMSTATE_* - Major change in Patch 14 - Dirty page tracking when vIOMMU is enabled using IOMMU notifier and its replay functionality - as suggested by Alex. - Some Structure changes to keep all migration related members at one place. - Pulled fix suggested by Zhi Wang <zhi.wang.linux@gmail.com> https://www.mail-archive.com/qemu-devel@nongnu.org/msg743722.html - Add comments where even suggested and required. v25 -> 26 - Removed emulated_config_bits cache and vdev->pdev.wmask from config space save load functions. - Used VMStateDescription for config space save and load functionality. - Major fixes from previous version review. https://www.mail-archive.com/qemu-devel@nongnu.org/msg714625.html v23 -> 25 - Updated config space save and load to save config cache, emulated bits cache and wmask cache. - Created idr string as suggested by Dr Dave that includes bus path. - Updated save and load function to read/write data to mixed regions, mapped or trapped. - When vIOMMU is enabled, created mapped iova range list which also keeps translated address. This list is used to mark dirty pages. This reduces downtime significantly with vIOMMU enabled than migration patches from previous version. - Removed get_address_limit() function from v23 patch as this not required now. v22 -> v23 -- Fixed issue reported by Yan https://lore.kernel.org/kvm/97977ede-3c5b-c5a5-7858-7eecd7dd531c@nvidia.com/ - Sending this version to test v23 kernel version patches: https://lore.kernel.org/kvm/1589998088-3250-1-git-send-email-kwankhede@nvidia.com/ v18 -> v22 - Few fixes from v18 review. But not yet fixed all concerns. I'll address those concerns in subsequent iterations. - Sending this version to test v22 kernel version patches: https://lore.kernel.org/kvm/1589781397-28368-1-git-send-email-kwankhede@nvidia.com/ v16 -> v18 - Nit fixes - Get migration capability flags from container - Added VFIO stats to MigrationInfo - Fixed bug reported by Yan https://lists.gnu.org/archive/html/qemu-devel/2020-04/msg00004.html v9 -> v16 - KABI almost finalised on kernel patches. - Added support for migration with vIOMMU enabled. v8 -> v9: - Split patch set in 2 sets, Kernel and QEMU sets. - Dirty pages bitmap is queried from IOMMU container rather than from vendor driver for per device. Added 2 ioctls to achieve this. v7 -> v8: - Updated comments for KABI - Added BAR address validation check during PCI device's config space load as suggested by Dr. David Alan Gilbert. - Changed vfio_migration_set_state() to set or clear device state flags. - Some nit fixes. 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 (17): 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 memory: Set DIRTY_MEMORY_MIGRATION when IOMMU is enabled vfio: Get migration capability flags for container vfio: Add function to start and stop dirty pages tracking vfio: Add vfio_listener_log_sync to mark dirty pages vfio: Dirty page tracking when vIOMMU is enabled vfio: Add ioctl to get dirty pages bitmap during dma unmap vfio: Make vfio-pci device migration capable qapi: Add VFIO devices migration stats in Migration stats hw/vfio/common.c | 441 +++++++++++++++++++- hw/vfio/meson.build | 1 + hw/vfio/migration.c | 940 ++++++++++++++++++++++++++++++++++++++++++ hw/vfio/pci.c | 84 +++- hw/vfio/pci.h | 1 - hw/vfio/trace-events | 21 + include/hw/vfio/vfio-common.h | 26 ++ migration/migration.c | 17 + monitor/hmp-cmds.c | 6 + qapi/migration.json | 17 + softmmu/memory.c | 2 +- 11 files changed, 1512 insertions(+), 44 deletions(-) create mode 100644 hw/vfio/migration.c