On 19.02.19 20:58, Michael S. Tsirkin wrote: > On Tue, Feb 19, 2019 at 10:06:35AM -0800, Alexander Duyck wrote: >>> I tend to like an asynchronous reporting approach as discussed in this >>> thread, we would have to see if Nitesh could get it implemented. >> >> I agree it would be great if it could work. However I have concerns >> given that work on this patch set dates back to 2017, major issues >> such as working around device assignment have yet to be addressed, > > BTW for device assignment to work, your idea of sending > data directly to kvm won't work, will it? > You need to update userspace so it can update VFIO right? > Another blocker for assignment is ability to make holes > an an existing mapping - supported by hardware but > not by IOMMU drivers. I had the exact same thought and then realized that we decided to block the balloon in user space until we figured out how to handle this properly. I wonder if MADV_FREE behaves differently compared to MADV_DONTNEED when finding pinned pages, but I doubt it. Most probably we'll have to disable hinting for device assignments as well. > > All the issues are shared with balloon btw, so that > could be another reason to use the balloon. Yes, smells like it. -- Thanks, David / dhildenb
