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(-)
--
2.7.4
