On Wed, Jun 02, 2010 at 12:04:04PM +0200, Joerg Roedel wrote: > On Wed, Jun 02, 2010 at 12:49:28PM +0300, Avi Kivity wrote: > > On 06/02/2010 12:45 PM, Joerg Roedel wrote: > >> IOMMU mapped memory can not be swapped out because we can't do demand > >> paging on io-page-faults with current devices. We have to pin _all_ > >> userspace memory that is mapped into an IOMMU domain. > > > > vhost doesn't pin memory. > > > > What I proposed is to describe the memory map using an object (fd), and > > pass it around to clients that use it: kvm, vhost, vfio. That way you > > maintain the memory map in a central location and broadcast changes to > > clients. Only a vfio client would result in memory being pinned. > > Ah ok, so its only about the database which keeps the mapping > information. > > > It can still work, but the interface needs to be extended to include > > dirty bitmap logging. > > Thats hard to do. I am not sure about VT-d but the AMD IOMMU has no > dirty-bits in the page-table. And without demand-paging we can't really > tell what pages a device has written to. The only choice is to mark all > IOMMU-mapped pages dirty as long as they are mapped. > > Joerg Or mark them dirty when they are unmapped. -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
