> -----Original Message----- > From: Tian, Kevin > Sent: Monday, July 31, 2017 2:55 PM > To: Zhang, Yulei <yulei.zh...@intel.com>; qemu-devel@nongnu.org > Cc: joonas.lahti...@linux.intel.com; zhen...@linux.intel.com; Zheng, Xiao > <xiao.zh...@intel.com>; Wang, Zhi A <zhi.a.w...@intel.com>; > alex.william...@redhat.com > Subject: RE: [Qemu-devel][RFC V2 0/4] vfio: Introduce Live migration > capability to vfio_mdev device > > > From: Zhang, Yulei > > Sent: Tuesday, May 9, 2017 3:59 PM > > > > 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 > > new vfio subtype region > VFIO_REGION_SUBTYPE_INTEL_IGD_DEVICE_STATE > > for Intel vGPU device, during the vfio device initialization, the mdev > > device will be set to migratable if the new region exist. > > Looking at your series, there is really nothing specific to vGPU or even Intel > vGPU regarding to device state save/restore... >
You are right, we may define a new subtype for it as it is common region for vfio device state save/restore. > > > > 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. And > > we use the first byte in the new region to control the running state > > of mdev device. > > > > Meanwhile we add one new ioctl VFIO_IOMMU_GET_DIRTY_BITMAP to > help 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, 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 > > > > 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 sub region 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 | 32 +++++++++ > > hw/vfio/pci.c | 164 > > +++++++++++++++++++++++++++++++++++++++++- > > hw/vfio/pci.h | 1 + > > include/hw/vfio/vfio-common.h | 1 + > > linux-headers/linux/vfio.h | 26 ++++++- > > 5 files changed, 220 insertions(+), 4 deletions(-) > > > > -- > > 2.7.4
