Hi Yan & Intel folks, I'm starting to run out of comments on this series, where are you with porting GVT-g migration to this API? Are there remaining blocking issues? Are we satisfied that the API is sufficient to support vIOMMU now? Thanks, Alex On Fri, 15 May 2020 02:07:39 +0530 Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote: > Hi, > > This patch set adds: > * IOCTL VFIO_IOMMU_DIRTY_PAGES to get dirty pages bitmap with > respect to IOMMU container rather than per device. All pages pinned by > vendor driver through vfio_pin_pages external API has to be marked as > dirty during migration. When IOMMU capable device is present in the > container and all pages are pinned and mapped, then all pages are marked > dirty. > When there are CPU writes, CPU dirty page tracking can identify dirtied > pages, but any page pinned by vendor driver can also be written by > device. As of now there is no device which has hardware support for > dirty page tracking. So all pages which are pinned should be considered > as dirty. > This ioctl is also used to start/stop dirty pages tracking for pinned and > unpinned pages while migration is active. > > * Updated IOCTL VFIO_IOMMU_UNMAP_DMA to get dirty pages bitmap before > unmapping IO virtual address range. > With vIOMMU, during pre-copy phase of migration, while CPUs are still > running, IO virtual address unmap can happen while device still keeping > reference of guest pfns. Those pages should be reported as dirty before > unmap, so that VFIO user space application can copy content of those > pages from source to destination. > > * Patch 8 detect if IOMMU capable device driver is smart to report pages > to be marked dirty by pinning pages using vfio_pin_pages() API. > > > Yet TODO: > Since there is no device which has hardware support for system memmory > dirty bitmap tracking, right now there is no other API from vendor driver > to VFIO IOMMU module to report dirty pages. In future, when such hardware > support will be implemented, an API will be required such that vendor > driver could report dirty pages to VFIO module during migration phases. > > Adding revision history from previous QEMU patch set to understand KABI > changes done till now > > v19 -> v20 > - Fixed ioctl to get dirty bitmap to get bitmap of multiple vfio_dmas > - Fixed unmap ioctl to get dirty bitmap of multiple vfio_dmas. > - Removed flag definition from migration capability. > > v18 -> v19 > - Updated migration capability with supported page sizes bitmap for dirty > page tracking and maximum bitmap size supported by kernel module. > - Added patch to calculate and cache pgsize_bitmap when iommu->domain_list > is updated. > - Removed extra buffers added in previous version for bitmap manipulation > and optimised the code. > > v17 -> v18 > - Add migration capability to the capability chain for VFIO_IOMMU_GET_INFO > ioctl > - Updated UMAP_DMA ioctl to return bitmap of multiple vfio_dma > > v16 -> v17 > - Fixed errors reported by kbuild test robot <lkp@xxxxxxxxx> on i386 > > v15 -> v16 > - Minor edits and nit picks (Auger Eric) > - On copying bitmap to user, re-populated bitmap only for pinned pages, > excluding unmapped pages and CPU dirtied pages. > - Patches are on tag: next-20200318 and 1-3 patches from Yan's series > https://lkml.org/lkml/2020/3/12/1255 > > v14 -> v15 > - Minor edits and nit picks. > - In the verification of user allocated bitmap memory, added check of > maximum size. > - Patches are on tag: next-20200318 and 1-3 patches from Yan's series > https://lkml.org/lkml/2020/3/12/1255 > > v13 -> v14 > - Added struct vfio_bitmap to kabi. updated structure > vfio_iommu_type1_dirty_bitmap_get and vfio_iommu_type1_dma_unmap. > - All small changes suggested by Alex. > - Patches are on tag: next-20200318 and 1-3 patches from Yan's series > https://lkml.org/lkml/2020/3/12/1255 > > v12 -> v13 > - Changed bitmap allocation in vfio_iommu_type1 to per vfio_dma > - Changed VFIO_IOMMU_DIRTY_PAGES ioctl behaviour to be per vfio_dma range. > - Changed vfio_iommu_type1_dirty_bitmap structure to have separate data > field. > > v11 -> v12 > - Changed bitmap allocation in vfio_iommu_type1. > - Remove atomicity of ref_count. > - Updated comments for migration device state structure about error > reporting. > - Nit picks from v11 reviews > > v10 -> v11 > - Fix pin pages API to free vpfn if it is marked as unpinned tracking page. > - Added proposal to detect if IOMMU capable device calls external pin pages > API to mark pages dirty. > - Nit picks from v10 reviews > > v9 -> v10: > - Updated existing VFIO_IOMMU_UNMAP_DMA ioctl to get dirty pages bitmap > during unmap while migration is active > - Added flag in VFIO_IOMMU_GET_INFO to indicate driver support dirty page > tracking. > - If iommu_mapped, mark all pages dirty. > - Added unpinned pages tracking while migration is active. > - Updated comments for migration device state structure with bit > combination table and state transition details. > > v8 -> v9: > - Split patch set in 2 sets, Kernel and QEMU. > - Dirty pages bitmap is queried from IOMMU container rather than from > vendor driver for per device. Added 2 ioctls to achieve this. > > v7 -> v8: > - Updated comments for KABI > - Added BAR address validation check during PCI device's config space load > as suggested by Dr. David Alan Gilbert. > - Changed vfio_migration_set_state() to set or clear device state flags. > - Some nit fixes. > > v6 -> v7: > - Fix build failures. > > v5 -> v6: > - Fix build failure. > > v4 -> v5: > - Added decriptive comment about the sequence of access of members of > structure vfio_device_migration_info to be followed based on Alex's > suggestion > - Updated get dirty pages sequence. > - As per Cornelia Huck's suggestion, added callbacks to VFIODeviceOps to > get_object, save_config and load_config. > - Fixed multiple nit picks. > - Tested live migration with multiple vfio device assigned to a VM. > > v3 -> v4: > - Added one more bit for _RESUMING flag to be set explicitly. > - data_offset field is read-only for user space application. > - data_size is read for every iteration before reading data from migration, > that is removed assumption that data will be till end of migration > region. > - If vendor driver supports mappable sparsed region, map those region > during setup state of save/load, similarly unmap those from cleanup > routines. > - Handles race condition that causes data corruption in migration region > during save device state by adding mutex and serialiaing save_buffer and > get_dirty_pages routines. > - Skip called get_dirty_pages routine for mapped MMIO region of device. > - Added trace events. > - Split into multiple functional patches. > > v2 -> v3: > - Removed enum of VFIO device states. Defined VFIO device state with 2 > bits. > - Re-structured vfio_device_migration_info to keep it minimal and defined > action on read and write access on its members. > > v1 -> v2: > - Defined MIGRATION region type and sub-type which should be used with > region type capability. > - Re-structured vfio_device_migration_info. This structure will be placed > at 0th offset of migration region. > - Replaced ioctl with read/write for trapped part of migration region. > - Added both type of access support, trapped or mmapped, for data section > of the region. > - Moved PCI device functions to pci file. > - Added iteration to get dirty page bitmap until bitmap for all requested > pages are copied. > > Thanks, > Kirti > > > > Kirti Wankhede (8): > vfio: UAPI for migration interface for device state > vfio iommu: Remove atomicity of ref_count of pinned pages > vfio iommu: Cache pgsize_bitmap in struct vfio_iommu > vfio iommu: Add ioctl definition for dirty pages tracking > vfio iommu: Implementation of ioctl for dirty pages tracking > vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap > vfio iommu: Add migration capability to report supported features > vfio: Selective dirty page tracking if IOMMU backed device pins pages > > drivers/vfio/vfio.c | 13 +- > drivers/vfio/vfio_iommu_type1.c | 565 ++++++++++++++++++++++++++++++++++++---- > include/linux/vfio.h | 4 +- > include/uapi/linux/vfio.h | 315 ++++++++++++++++++++++ > 4 files changed, 838 insertions(+), 59 deletions(-) >
