On 1/29/2021 4:55 PM, Alex Williamson wrote: > 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, Thanks Alex, it's great to be down to nits! I am done for today but I will look at the vaddr-v3 branch and respond to all your comments tomorrow. - Steve
