Hello, I'm working on NetBSD Xen support.
Recently, we've switched to grant version 2 mainly for the improved status handling, and eventually for copy-only subpage grant support, which I'd like to experiment with in our netback driver. Currently we don't need the 64-bit frame, which I found was reason to Linux was switched over to v2 a while ago. However, later found out that HVM doesn't actually seem to support the GNTTABOP_get_status_frames hypercall, so had to fall back to v1 for HVM. Code in xen/arch/x86/hvm/hypercall.c, which doesn't have any handling in GNTTABOP_get_status_frames neither in Xen 4.11/4.12/4.13. Can you advise which version should be used by Dom0/DomU kernels? Is there some way to still use v2 with HVM? Possibly instead of using the status frames, still use the old cmpxchg16 method on hdr.flags, but as I understand hdr.flags is not used for GTF_reading and GTF_writing in v2. I also see the set_version and get_version calls are still supported even for HVM. Understandably, we'd prefer to use same version for PV and HVM kernels. Thanks. Jaromir
