Hello, This series is based on the previous one that added the basic VFIO migration protocol v2 implementation [1].
The first patch in the series starts by adding pre-copy support for VFIO migration protocol v2. Pre-copy support allows the VFIO device data to be transferred while the VM is running. This can improve performance and reduce migration downtime. Full description of it can be found here [2]. The series then moves on to implement device dirty page tracking. Device dirty page tracking allows the VFIO device to record its DMAs and report them back when needed. This is part of VFIO migration and is used during pre-copy phase of migration to track the RAM pages that the device has written to and mark those pages dirty, so they can later be re-sent to target. Device dirty page tracking uses the DMA logging uAPI to discover device capabilities, to start and stop tracking, and to get dirty page bitmap report. Extra details and uAPI definition can be found here [3]. Device dirty page tracking operates in VFIOContainer scope. I.e., When dirty tracking is started, stopped or dirty page report is queried, all devices within a VFIOContainer are iterated and for each of them device dirty page tracking is started, stopped or dirty page report is queried, respectively. Device dirty page tracking is used only if all devices within a VFIOContainer support it. Otherwise, VFIO IOMMU dirty page tracking is used, and if that is not supported as well, memory is perpetually marked dirty by QEMU. Note that since VFIO IOMMU dirty page tracking has no HW support, the last two usually have the same effect of perpetually marking all pages dirty. Normally, when asked to start dirty tracking, all the currently DMA mapped ranges are tracked by device dirty page tracking. However, when vIOMMU is enabled IOVA ranges are DMA mapped/unmapped on the fly as the vIOMMU maps/unmaps them. These IOVA ranges can potentially be mapped anywhere in the vIOMMU IOVA space. Due to this dynamic nature of vIOMMU mapping/unmapping, tracking only the currently DMA mapped IOVA ranges doesn't work very well. Thus, when vIOMMU is enabled, we try to track the entire vIOMMU IOVA space. If that fails (IOVA space can be rather big and we might hit HW limitation), we try to track smaller range while marking untracked ranges dirty. Patch breakdown: - Patch 1 adds VFIO migration pre-copy support. - Patches 2-8 fix bugs and do some preparatory work required prior to adding device dirty page tracking. - Patches 9-11 implement device dirty page tracking. - Patches 12-16 add vIOMMU support to device dirty page tracking. - Patches 17-18 enable device dirty page tracking and document it. Thanks. [1] https://lore.kernel.org/qemu-devel/20230116141135.12021-1-avih...@nvidia.com/ [2] https://lore.kernel.org/kvm/20221206083438.37807-3-yish...@nvidia.com/ [3] https://lore.kernel.org/netdev/20220908183448.195262-4-yish...@nvidia.com/ Avihai Horon (12): vfio/migration: Add VFIO migration pre-copy support vfio/common: Fix error reporting in vfio_get_dirty_bitmap() vfio/common: Fix wrong %m usages vfio/common: Abort migration if dirty log start/stop/sync fails vfio/common: Add VFIOBitmap and (de)alloc functions vfio/common: Extract code from vfio_get_dirty_bitmap() to new function vfio/common: Extract vIOMMU code from vfio_sync_dirty_bitmap() memory/iommu: Add IOMMU_ATTR_MAX_IOVA attribute intel-iommu: Implement get_attr() method vfio/common: Support device dirty page tracking with vIOMMU vfio/common: Optimize device dirty page tracking with vIOMMU docs/devel: Document VFIO device dirty page tracking Joao Martins (6): util: Add iova_tree_nnodes() util: Extend iova_tree_foreach() to take data argument vfio/common: Record DMA mapped IOVA ranges vfio/common: Add device dirty page tracking start/stop vfio/common: Add device dirty page bitmap sync vfio/migration: Query device dirty page tracking support docs/devel/vfio-migration.rst | 79 ++-- include/exec/memory.h | 3 +- include/hw/vfio/vfio-common.h | 10 + include/qemu/iova-tree.h | 19 +- hw/i386/intel_iommu.c | 18 + hw/vfio/common.c | 866 ++++++++++++++++++++++++++++++---- hw/vfio/migration.c | 127 ++++- util/iova-tree.c | 23 +- hw/vfio/trace-events | 5 +- 9 files changed, 1006 insertions(+), 144 deletions(-) -- 2.26.3
