"KVM Chainsaw" Expected To Hit Linux 7.3 For Dealing With God Data Structure - Phoronix

What the report says

Phoronix reported on July 26, 2026, that a KVM patch series nicknamed “KVM Chainsaw” is likely to be submitted for the Linux 7.3 merge window. The work has been merged by Red Hat engineer and KVM maintainer Paolo Bonzini into KVM’s “next” Git branch, a staging area for changes expected to move toward the mainline kernel.

The series targets the kvm_mmu structure, which Bonzini described as an overloaded “god data structure” because it combines several roles related to guest page-table format description, page-table walking and page-table construction. The cleanup divides those responsibilities into three components: kvm_pagewalk for walking page tables, kvm_mmu for building page tables, and kvm_page_format for operating on existing page-table entries and reserved-bit handling.

According to the report, the change is intended to make KVM’s memory-management code easier to reason about, especially around terminology and behavior involving guest_mmu and nested_mmu. The restructuring may also help future feature work by improving code reuse; Bonzini noted that the final patch demonstrates a path toward supporting certain shadow page table entries not yet handled by KVM.

KVM is the Linux kernel’s built-in virtualization technology, widely used by hypervisors and cloud infrastructure. While this series is primarily a code-maintenance change rather than a user-facing feature, such cleanups can matter because they reduce complexity in critical kernel subsystems. Phoronix said the Linux 7.3 merge window is expected in the second half of August.