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

[Marc Zyngier <maz@kernel.org>]

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.

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