On Fri, 29 Jan 2021 10:48:10 -0500 Steven Sistare <steven.sistare@xxxxxxxxxx> wrote: > Hi Alex, thanks for the feedback on V2. Any more comments before I submit V3? Nope, I'm ok with your proposals. Thanks, Alex > On 1/19/2021 12:48 PM, Steve Sistare 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 1-4 define and implement the flag to unmap all ranges. > > Patches 5-6 define and implement the flags to update vaddr. > > Patches 7-9 add blocking to complete the implementation. > > > > Changes from V1: > > - 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 > > > > Steve Sistare (9): > > vfio: option to unmap all > > vfio/type1: find first dma > > vfio/type1: unmap cleanup > > vfio/type1: implement unmap all > > vfio: interfaces to update vaddr > > 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 | 229 ++++++++++++++++++++++++++++++++++------ > > include/linux/vfio.h | 5 + > > include/uapi/linux/vfio.h | 27 +++++ > > 4 files changed, 231 insertions(+), 35 deletions(-) > > >
