On Tue, Jan 13, 2026 at 04:37:08PM +0100, Magnus Kulke wrote: > This change removes userland code that worked around a restriction > in the mshv driver in the 6.18 kernel: regions from userland > couldn't be mapped to multiple regions in the kernel. We maintained a > shadow mapping table in qemu and used a heuristic to swap in a requested > region in case of UNMAPPED_GPA exits. > > However, this heuristic wasn't reliable in all cases, since HyperV > behaviour is not 100% reliable across versions. HyperV itself doesn't > prohibit to map regions at multiple places into the guest, so the > restriction has been removed in the mshv driver. > > Hence we can remove the remapping code. Effectively this will mandate a > 6.19 kernel, if the workload attempt to map e.g. BIOS to multiple > reagions. I still think it's the right call to remove this logic: > > - The workaround only seems to work reliably with a certain revision > of HyperV as a nested hypervisor. > - We expect Direct Virtualization (L1VH) to be the main platform for > the mshv accelerator, which also requires a 6.19 kernel > > This reverts commit efc4093358511a58846a409b965213aa1bb9f31a. > > Signed-off-by: Magnus Kulke <[email protected]>
Acked-by: Wei Liu (Microsoft) <[email protected]>
