Hi Yulei Zhang, This series is same as the previous version, that is, there is no pre-copy phase. This only takes care of stop-and-copy phase. As per we discussed in KVM Forum 2017 in October, there should be provision of pre-copy phase.
Thanks, Kirti On 3/5/2018 11:30 AM, Yulei Zhang wrote: > Summary > > This series RFC would like to resume the discussion about how to > introduce the live migration capability to vfio mdev device. > > By adding a new vfio subtype region VFIO_REGION_SUBTYPE_DEVICE_STATE, > the mdev device will be set to migratable if the new region exist > during the initialization. > > The intention to add the new region is using it for mdev device status > save and restore during the migration. The access to this region > will be trapped and forward to the mdev device driver, it also uses > the first byte in the new region to control the running state of mdev > device, so during the migration after stop the mdev driver, qemu could > retrieve the specific device status from this region and transfer to > the target VM side for the mdev device restore. > > In addition, we add one new ioctl VFIO_IOMMU_GET_DIRTY_BITMAP to help do > the mdev device dirty page synchronization during the migration, currently > it is just for static copy, in the future we would like to add new interface > for the pre-copy. > > Below is the vfio_mdev device migration sequence > Source VM side: > start migration > | > V > get the cpu state change callback, write to the > subregion's first byte to stop the mdev device > | > V > quary the dirty page bitmap from iommu container > and add into qemu dirty list for synchronization > | > V > save the deivce status into Qemufile which is > read from the vfio device subregion > > Target VM side: > restore the mdev device after get the > saved status context from Qemufile > | > V > get the cpu state change callback > write to subregion's first byte to > start the mdev device to put it in > running status > | > V > finish migration > > V3->V2: > 1. rebase the patch to Qemu stable 2.10 branch. > 2. use a common name for the subregion instead of specific for > intel IGD. > > V1->V2: > Per Alex's suggestion: > 1. use device subtype region instead of VFIO PCI fixed region. > 2. remove unnecessary ioctl, use the first byte of subregion to > control the running state of mdev device. > 3. for dirty page synchronization, implement the interface with > VFIOContainer instead of vfio pci device. > > Yulei Zhang (4): > vfio: introduce a new VFIO subregion for mdev device migration support > vfio: Add vm status change callback to stop/restart the mdev device > vfio: Add struct vfio_vmstate_info to introduce put/get callback > funtion for vfio device status save/restore > vifo: introduce new VFIO ioctl VFIO_IOMMU_GET_DIRTY_BITMAP > > hw/vfio/common.c | 34 +++++++++ > hw/vfio/pci.c | 171 > +++++++++++++++++++++++++++++++++++++++++- > hw/vfio/pci.h | 1 + > include/hw/vfio/vfio-common.h | 1 + > linux-headers/linux/vfio.h | 29 ++++++- > 5 files changed, 232 insertions(+), 4 deletions(-) >