On Fri, 29 Jan 2021 08:54:03 -0800 Steve Sistare <steven.sistare@xxxxxxxxxx> wrote: > Add interfaces that allow the underlying memory object of an iova range > to be mapped to a new virtual address in the host process: > > - VFIO_DMA_UNMAP_FLAG_VADDR for VFIO_IOMMU_UNMAP_DMA > - VFIO_DMA_MAP_FLAG_VADDR flag for VFIO_IOMMU_MAP_DMA > - VFIO_UPDATE_VADDR for VFIO_CHECK_EXTENSION > - VFIO_DMA_UNMAP_FLAG_ALL for VFIO_IOMMU_UNMAP_DMA > - VFIO_UNMAP_ALL for VFIO_CHECK_EXTENSION > > Unmap-vaddr invalidates the host virtual address in an iova range and blocks > vfio translation of host virtual addresses, but DMA to already-mapped pages > continues. Map-vaddr updates the base VA and resumes translation. The > implementation supports iommu type1 and mediated devices. Unmap-all allows > all ranges to be unmapped or invalidated in a single ioctl, which simplifies > userland code. > > This functionality is necessary for live update, in which a host process > such as qemu exec's an updated version of itself, while preserving its > guest and vfio devices. The process blocks vfio VA translation, exec's > its new self, mmap's the memory object(s) underlying vfio object, updates > the VA, and unblocks translation. For a working example that uses these > new interfaces, see the QEMU patch series "[PATCH V2] Live Update" at > https://lore.kernel.org/qemu-devel/1609861330-129855-1-git-send-email-steven.sistare@xxxxxxxxxx > > Patches 1-3 define and implement the flag to unmap all ranges. > Patches 4-6 define and implement the flags to update vaddr. > Patches 7-9 add blocking to complete the implementation. Hi Steve, It looks pretty good to me, but I have some nit-picky comments that I'll follow-up with on the individual patches. However, I've made the changes I suggest in a branch that you can find here: git://github.com/awilliam/linux-vfio.git vaddr-v3 If the changes look ok, just send me an ack, I don't want to attribute something to you that you don't approve of. Thanks, Alex > Changes in V2: > - define a flag for unmap all instead of special range values > - define the VFIO_UNMAP_ALL extension > - forbid the combination of unmap-all and get-dirty-bitmap > - unwind in unmap on vaddr error > - add a new function to find first dma in a range instead of modifying > an existing function > - change names of update flags > - fix concurrency bugs due to iommu lock being dropped > - call down from from vfio to a new backend interface instead of up from > driver to detect container close > - use wait/wake instead of sleep and polling > - refine the uapi specification > - split patches into vfio vs type1 > > Changes in V3: > - add vaddr_invalid_count to fix pin_pages race with unmap > - refactor the wait helper functions > - traverse dma entries more efficiently in unmap > - check unmap flag conflicts more explicitly > - rename some local variables and functions > > Steve Sistare (9): > vfio: option to unmap all > vfio/type1: unmap cleanup > vfio/type1: implement unmap all > vfio: interfaces to update vaddr > vfio/type1: massage unmap iteration > vfio/type1: implement interfaces to update vaddr > vfio: iommu driver notify callback > vfio/type1: implement notify callback > vfio/type1: block on invalid vaddr > > drivers/vfio/vfio.c | 5 + > drivers/vfio/vfio_iommu_type1.c | 251 +++++++++++++++++++++++++++++++++++----- > include/linux/vfio.h | 5 + > include/uapi/linux/vfio.h | 27 +++++ > 4 files changed, 256 insertions(+), 32 deletions(-) >
