On Mon, Sep 29, 2025 at 04:02:59PM +0000, Stanislav Kinsburskii wrote: > From the start, the root-partition driver allocates, pins, and maps all > guest memory into the hypervisor at guest creation. This is simple: Linux > cannot move the pages, so the guest’s view in Linux and in Microsoft > Hypervisor never diverges. > > However, this approach has major drawbacks: > - NUMA: affinity can’t be changed at runtime, so you can’t migrate guest > memory closer to the CPUs running it → performance hit. > - Memory management: unused guest memory can’t be swapped out, compacted, or > merged. > - Provisioning time: upfront allocation/pinning slows guest create/destroy. > - Overcommit: no memory overcommit on hosts with pinned-guest memory. > > This series adds movable memory pages for Hyper-V child partitions. Guest > pages are no longer allocated upfront; they’re allocated and mapped into > the hypervisor on demand (i.e., when the guest touches a GFN that isn’t yet > backed by a host PFN). > When a page is moved, Linux no longer holds it and it is unmapped from the > hypervisor. > As a result, Hyper-V guests behave like regular Linux processes, enabling > standard Linux memory features to apply to guests. > > Exceptions (still pinned): > 1. Encrypted guests (explicit). > 2 Guests with passthrough devices (implicitly pinned by the VFIO framework). > > v2: > - Split unmap batching into a separate patch. > - Fixed commit messages from v1 review. > - Renamed a few functions for clarity. > > --- > > Stanislav Kinsburskii (4): > Drivers: hv: Refactor and rename memory region handling functions > Drivers: hv: Centralize guest memory region destruction > Drivers: hv: Batch GPA unmap operations to improve large region > performance > Drivers: hv: Add support for movable memory regions >
Our internal test discovered an issue which caused a kernel panic. Has that been fixed in this series? Without fixing that bug or ruling out problems in the code I don't think I can merge this. Once this feature goes into other people's systems it will be extremely difficult to debug. Wei > > drivers/hv/Kconfig | 1 > drivers/hv/mshv_root.h | 10 + > drivers/hv/mshv_root_hv_call.c | 2 > drivers/hv/mshv_root_main.c | 472 > +++++++++++++++++++++++++++++++++------- > 4 files changed, 403 insertions(+), 82 deletions(-) >
