Hi Wei-Lin, Thank you very much for the series.
I haven't had time to read through much of this yet, but I noticed Itaru's comment about leaving stage-1 translation disabled for the L2. Since selftests expects things like atomics to work we will definitely need the stage-1 MMU to be enabled w/ Normal mappings (this was broken in the past [*]). I wonder if we can (ab)use the pre-existing stage-1 tables that the selftests library creates on behalf of the L1. After all, L1 and L2 are both effectively in the same virtual address space. [*] https://lore.kernel.org/kvmarm/[email protected]/ Thanks, Oliver On Sat, May 16, 2026 at 07:29:54PM +0100, Wei-Lin Chang wrote: > Hi, > > This is v3 of adding basic support for running nested guests (L2) in > kselftest. This time a framework for enabling stage-2 in the guest is > added, including the s2_mmu struct, s2 translation control setup, and > a stage-2 page table generator. Similar to L2 vCPU management, all > stage-2 work is done in the guest instead of userspace. > > An additional shadow_stage2 test is added which leverages the framework > to run L2 with stage-2 enabled. > > * Changes from v2 [1]: > > - Update vm_paddr_t to gpa_t, vm_vaddr_t to gva_t. > > - Added framework for enabling stage-2 in the guest. > > - Added shadow_stage2 test. > > Thanks! > > [1]: > https://lore.kernel.org/kvmarm/[email protected]/ > > Wei-Lin Chang (9): > KVM: arm64: selftests: Add GPR save/restore functions for NV > KVM: arm64: selftests: Add helpers for guest hypervisors > KVM: arm64: selftests: Add hello_nested basic NV selftest > KVM: arm64: selftests: Enhance hello_nested test > KVM: arm64: selftests: Add shadow_stage2 test > KVM: arm64: selftests: shadow_stage2: Allocate L2 stack from dedicated > pool > KVM: arm64: selftests: shadow_stage2: Check supported stage-2 granule > size > KVM: arm64: selftests: Add infrastructure for using stage-2 in guest > KVM: arm64: selftests: shadow_stage2: Turn on stage-2 translation for > the nested guest > > tools/testing/selftests/kvm/Makefile.kvm | 5 + > .../selftests/kvm/arm64/hello_nested.c | 134 +++++++++ > .../selftests/kvm/arm64/shadow_stage2.c | 165 +++++++++++ > .../selftests/kvm/include/arm64/nested.h | 85 ++++++ > tools/testing/selftests/kvm/lib/arm64/entry.S | 137 +++++++++ > .../selftests/kvm/lib/arm64/hyp-entry.S | 77 +++++ > .../testing/selftests/kvm/lib/arm64/nested.c | 264 ++++++++++++++++++ > 7 files changed, 867 insertions(+) > create mode 100644 tools/testing/selftests/kvm/arm64/hello_nested.c > create mode 100644 tools/testing/selftests/kvm/arm64/shadow_stage2.c > create mode 100644 tools/testing/selftests/kvm/include/arm64/nested.h > create mode 100644 tools/testing/selftests/kvm/lib/arm64/entry.S > create mode 100644 tools/testing/selftests/kvm/lib/arm64/hyp-entry.S > create mode 100644 tools/testing/selftests/kvm/lib/arm64/nested.c > > -- > 2.43.0 > >
