[PATCH v3 00/11] KVM: Mapping guest_memfd backed memory at the host for software protected VMs

[Fuad Tabba <tabba@google.com>]

Changes since v2 [1]:
- Added more documentation
- Hook the folio_put callback as a stub with a warning
- Tidying up and refactoring
- Rebased on Linux 6.14-rc2

The purpose of this series is to serve as a base for _restricted_
mmap() support for guest_memfd backed memory at the host [2]. It
would allow experimentation with what that support would be like
in the safe environment of the software VM types, which are meant
for testing and experimentation.

For more background and how to test this series, please refer to v2 [1].

Cheers,
/fuad

[1] https://lore.kernel.org/all/20250129172320.950523-1-tabba@google.com/
[2] https://lore.kernel.org/all/20250117163001.2326672-1-tabba@google.com/

Fuad Tabba (11):
  mm: Consolidate freeing of typed folios on final folio_put()
  KVM: guest_memfd: Handle final folio_put() of guest_memfd pages
  KVM: guest_memfd: Allow host to map guest_memfd() pages
  KVM: guest_memfd: Add KVM capability to check if guest_memfd is shared
  KVM: guest_memfd: Handle in-place shared memory as guest_memfd backed
    memory
  KVM: x86: Mark KVM_X86_SW_PROTECTED_VM as supporting guest_memfd
    shared memory
  KVM: arm64: Refactor user_mem_abort() calculation of force_pte
  KVM: arm64: Handle guest_memfd()-backed guest page faults
  KVM: arm64: Introduce KVM_VM_TYPE_ARM_SW_PROTECTED machine type
  KVM: arm64: Enable mapping guest_memfd in arm64
  KVM: guest_memfd: selftests: guest_memfd mmap() test when mapping is
    allowed

 Documentation/virt/kvm/api.rst                |   5 +
 arch/arm64/include/asm/kvm_host.h             |  10 ++
 arch/arm64/kvm/Kconfig                        |   1 +
 arch/arm64/kvm/arm.c                          |   5 +
 arch/arm64/kvm/mmu.c                          |  91 ++++++++++------
 arch/x86/include/asm/kvm_host.h               |   5 +
 arch/x86/kvm/Kconfig                          |   3 +-
 include/linux/kvm_host.h                      |  28 ++++-
 include/linux/page-flags.h                    |  32 ++++++
 include/uapi/linux/kvm.h                      |   7 ++
 mm/debug.c                                    |   1 +
 mm/swap.c                                     |  32 +++++-
 tools/testing/selftests/kvm/Makefile.kvm      |   1 +
 .../testing/selftests/kvm/guest_memfd_test.c  |  75 +++++++++++--
 tools/testing/selftests/kvm/lib/kvm_util.c    |   3 +-
 virt/kvm/Kconfig                              |   4 +
 virt/kvm/guest_memfd.c                        | 100 ++++++++++++++++++
 virt/kvm/kvm_main.c                           |   9 +-
 18 files changed, 360 insertions(+), 52 deletions(-)


base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3
-- 
2.48.1.502.g6dc24dfdaf-goog