Re: [PATCH v4 12/21] KVM: selftests: Add a stage-2 MMU instance to kvm_vm

Yosry Ahmed
2026-01-02T17:04:19Z

On Tue, Dec 30, 2025 at 03:01:41PM -0800, Sean Christopherson wrote:
> Add a stage-2 MMU instance so that architectures that support nested
> virtualization (more specifically, nested stage-2 page tables) can create
> and track stage-2 page tables for running L2 guests. Plumb the structure
> into common code to avoid cyclical dependencies, and to provide some line
> of sight to having common APIs for creating stage-2 mappings.
>
> As a bonus, putting the member in common code justifies using stage2_mmu
> instead of tdp_mmu for x86.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>

> ---
> tools/testing/selftests/kvm/include/kvm_util.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index c1497515fa6a..371d55e0366e 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -116,7 +116,12 @@ struct kvm_vm {
> uint32_t dirty_ring_size;
> uint64_t gpa_tag_mask;
>
> + /*
> + * "mmu" is the guest's stage-1, with a short name because the vast
> + * majority of tests only care about the stage-1 MMU.
> + */
> struct kvm_mmu mmu;
> + struct kvm_mmu stage2_mmu;
>
> struct kvm_vm_arch arch;
>
> --
> 2.52.0.351.gbe84eed79e-goog
>