[PATCH 0/4] KVM: arm64: Reduce overhead of full S2 teardown

[Itaru Kitayama]

Hi Marc,

On Sat, Sep 12, 2026 at 11:48:30AM +0100, Marc Zyngier wrote:
> Tearing down a full S2 is a pretty involved process, resulting in a
> lot of TLB invalidation. These TLBIs are either on a per leaf basis if
> the HW doesn't support range invalidation, or by top-level range if it
> does. Amusingly, the latter occurs even when nothing has been
> unmapped.
> 
> Things are made worse with NV, as we have a bucket-load of shadow S2s,
> and the need to invalidate them all on the back of an MMU notifier.
> The latter will eventually be solved by the reverse-map tracking that
> Wei-Lin is working on, but we need to be better at full-S2 teardown.
> 
> This small series adds a "no TLBI" unmapping primitive, which allows
> the caller to then whack the TLBs using a VMID-wide invalidation. This
> results in far fewer TLBIs, and a better recursive virtualisation as
> we get far fewer traps as a consequence.
> 
> This applies on top of my shadow-s2 lifetime fixes, and is expected to
> be a prefix to Wei-Lin's series.

I've tested this series on QEMU with TCG mode, and it boots.

Tested-by: Itaru Kitayama <itaru.kitayama at fujitsu.com>

Thanks,
Itaru.

> 
> Marc Zyngier (4):
>   KVM: arm64: pgtable: Add Stage-2 unmap without TLBI primitive
>   KVM: arm64: MMU: Add kvm_stage2_unmap_all() helper
>   KVM: arm64: nv: Move full s2_mmu unmap over to kvm_stage2_unmap_all()
>   KVM: arm64: nv: Move TLBI VMALLS12E1* emulation over to
>     kvm_stage2_unmap_all()
> 
>  arch/arm64/include/asm/kvm_mmu.h     |  1 +
>  arch/arm64/include/asm/kvm_pgtable.h | 17 +++++++++++++
>  arch/arm64/include/asm/kvm_pkvm.h    |  1 +
>  arch/arm64/kvm/hyp/pgtable.c         | 38 +++++++++++++++++++++-------
>  arch/arm64/kvm/mmu.c                 | 15 +++++++++++
>  arch/arm64/kvm/nested.c              |  4 +--
>  arch/arm64/kvm/pkvm.c                |  2 ++
>  arch/arm64/kvm/sys_regs.c            | 18 ++++++-------
>  8 files changed, 75 insertions(+), 21 deletions(-)
> 
> -- 
> 2.47.3
> 
>