Sorry for the delayed answer, but I look at the vmap_pfn usage in the previous version and tried to come up with a better version. This mostly untested branch: http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/hyperv-vmap get us there for swiotlb and the channel infrastructure I've started looking at the network driver and didn't get anywhere due to other work. As far as I can tell the network driver does gigantic multi-megabyte vmalloc allocation for the send and receive buffers, which are then passed to the hardware, but always copied to/from when interacting with the networking stack. Did I see that right? Are these big buffers actually required unlike the normal buffer management schemes in other Linux network drivers? If so I suspect the best way to allocate them is by not using vmalloc but just discontiguous pages, and then use kmap_local_pfn where the PFN includes the share_gpa offset when actually copying from/to the skbs.
