* Yulei Zhang (yulei.zh...@intel.com) wrote: > Summary > > This series RFC would like to introduce the live migration capability > to vfio_mdev device. > > As currently vfio_mdev device don't support migration, we introduce a > device flag VFIO_DEVICE_FLAGS_MIGRATABLE to help determine whether the > mdev device can be migrate or not, it will check the flag during the > device initialization and decide to init the new vfio region > VFIO_PCI_DEVICE_STATE_REGION_INDEX. > > The intention to add the new region is using it for vfio_mdev device > status save and restore during the migration. The access to this region > will be trapped and forward to the vfio_mdev device driver. There is > an alternative way to achieve it is to add a new vfio ioctl to help fetch > and save the device status. > > Also this series include two new vfio ioctl > #define VFIO_DEVICE_PCI_STATUS_SET _IO(VFIO_TYPE, VFIO_BASE + 14) > #define VFIO_DEVICE_PCI_GET_DIRTY_BITMAP _IO(VFIO_TYPE, VFIO_BASE + 15) > > The first one is used to contorl the device running status, we want to > stop the mdev device before quary the status from its device driver and > restart the device after migration. > The second one is used to do the mdev device dirty page synchronization. > > So the vfio_mdev device migration sequence would be > Source VM side: > start migration > | > V > get the cpu state change callback > use status set ioctl to stop the mdev device > | > V > save the deivce status into Qemufile which is > read from the new vfio device status region > | > V > quary the dirty page bitmap from deivce > and add into qemu dirty list for sync
That ordering is interesting; I think the main migration flow is normally to complete migration of RAM and then migrate the devices; so I worry about that order. Dave > Target VM side: > restore the mdev device after get the > saved status context from Qemufile > | > V > get the cpu state change callback > use status set ioctl to start the mdev > device to put it in running status > | > V > finish migration > > Yulei Zhang (5): > vfio: introduce a new VFIO region for migration support > vfio: Add struct vfio_vmstate_info to introduce vfio device put/get > funtion > vfio: introduce new VFIO ioctl VFIO_DEVICE_PCI_STATUS_SET > vfio: use vfio_device_put/vfio_device_get for device status > save/restore > vifo: introduce new VFIO ioctl VFIO_DEVICE_PCI_GET_DIRTY_BITMAP > > hw/vfio/pci.c | 204 > ++++++++++++++++++++++++++++++++++++++++++++- > hw/vfio/pci.h | 3 + > linux-headers/linux/vfio.h | 34 +++++++- > 3 files changed, 239 insertions(+), 2 deletions(-) > > -- > 2.7.4 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
