[PATCH v2 00/22] Huge mapping support for protected VMs

[Vincent Donnefort]

Currently, pKVM handles stage-2 mappings and ownership tracking strictly
at the PAGE_SIZE level. This series extends pKVM to support PMD_SIZE
block mappings, thereby enabling Transparent Huge Pages (THP) for
protected guests. hugetlbfs is currently unsupported as it does not
appear as swapbacked.

Summary of changes:

1. Enable host stage-2 block-level annotations:

The host stage-2 being annotated with the GFN of the guest on the
host->guest donation transitions, we allow block-level annotations to
ensure the host stage-2 mapping size matches the guest stage-2.

2. Expand ownership transition HVCs:

Enable the ownership test to work with PMD_SIZE so we can test
transitions supporting more than PAGE_SIZE.

3. Implements the PKVM_HYP_REQ_SPLIT hypervisor request:

Allows the hypervisor to ask the host to split a mapping. This ensures
the guest s2, pkvm_mapping tree and host s2 are always using the same
mapping size.

4. Wires up THP support for protected VMs:

Use a PMD_SIZE mapping for protected VMs whenever
transparent_hugepage_adjust() acknowledge the presence of a huge-mapping
in the VMM stage-1.

Changelog:

v2:
  - Reorder patches to make the series bisectable.
  - Check memcache and WARN_ON if stage-2 split fails in __pkvm_host_split_guest()
  - __pkvm_pgtable_stage2_split(): return 0 if the block is already split.
  - kvm_pgtable_stage2_table_install() to let mem_protect handle the stage-2 splitting.
  - Refactor fix_host_ownership() (Wei-Lin)
  - Handle non-linear mappings in fix_host_ownership()
  - Drop _page_ from __pkvm_host_reclaim_page_guest and __pkvm_reclaim_dying_guest_page() (Wei-Lin)
  - Make a separate patch for hyp_poison_range() (Wei-Lin)
  - Use folio_add_pins in __pkvm_pgtable_stage2_split() (Wei-Lin)
  - Hold the mmap_read_lock() for transparent_hugepage_adjust() (Sashiko)
  - Catch 2MiB fault on existing 4KiB fault (Sashiko)
  - Add share/unshare testing of split blocks.
  - Rebased on 7.3-rc2

v1 (https://lore.kernel.org/all/20260803100904.3563942-1-vdonnefort@google.com/)

Keir Fraser (1):
  KVM: arm64: Prefault host stage-2 entries on block split

Vincent Donnefort (21):
  KVM: arm64: Propagate host stage-2 annotated entries on block split
  KVM: arm64: Allow block-level stage-2 annotation
  KVM: arm64: Use block-level annotations when setting up the host
    stage-2
  KVM: arm64: Make pKVM ownership selftest an HVC
  KVM: arm64: Add a range to __pkvm_host_share/unshare_hyp()
  KVM: arm64: Add a range to __pkvm_host_donate_guest()
  KVM: arm64: Add a range to hyp_poison_page()
  KVM: arm64: Add a range to __pkvm_host_reclaim_guest()
  KVM: arm64: Add a range to __pkvm_guest_share_host()
  KVM: arm64: Add a range to __pkvm_guest_unshare_host()
  KVM: arm64: Handle huge mappings in
    __pkvm_host_force_reclaim_page_guest()
  KVM: arm64: Handle huge mappings in __pkvm_vcpu_in_poison_fault()
  KVM: arm64: Add a range to pKVM ownership selftest
  KVM: arm64: Warn on pKVM guest stage-2 block collapse
  KVM: arm64: Add pkvm_hyp_req infrastructure
  KVM: arm64: Introduce kvm_pgtable_stage2_table_install()
  KVM: arm64: Add __pkvm_host_split_guest HVC
  KVM: arm64: Extend pKVM page ownership selftests to cover guest block
    split
  KVM: arm64: Add PKVM_HYP_REQ_SPLIT
  KVM: arm64: Raise PKVM_HYP_REQ_SPLIT on guest to host sharing
  KVM: arm64: Stage-2 huge mappings for protected VMs

 arch/arm64/include/asm/kvm_asm.h              |  14 +-
 arch/arm64/include/asm/kvm_host.h             |  19 +
 arch/arm64/include/asm/kvm_pgtable.h          |  12 +
 arch/arm64/include/asm/kvm_pkvm.h             |  18 +-
 arch/arm64/kvm/arm.c                          |   2 +
 arch/arm64/kvm/handle_exit.c                  |   3 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  25 +-
 arch/arm64/kvm/hyp/include/nvhe/memory.h      |   5 +
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h        |   6 +-
 arch/arm64/kvm/hyp/nvhe/ffa.c                 |  12 +-
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  48 +-
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 588 ++++++++++++------
 arch/arm64/kvm/hyp/nvhe/pkvm.c                |  59 +-
 arch/arm64/kvm/hyp/nvhe/setup.c               | 140 +++--
 arch/arm64/kvm/hyp/pgtable.c                  | 137 +++-
 arch/arm64/kvm/mmu.c                          | 119 ++--
 arch/arm64/kvm/pkvm.c                         | 230 ++++++-
 arch/arm64/kvm/trace_pkvm.h                   |  44 ++
 18 files changed, 1129 insertions(+), 352 deletions(-)
 create mode 100644 arch/arm64/kvm/trace_pkvm.h


base-commit: df2908090cda368b01ff43709f51890076c56157
-- 
2.55.0.1007.g17ff1f9808-goog