[PATCH v6 00/10] KVM: Mapping guest_memfd backed memory at the host for software protected VMs

[Fuad Tabba <tabba@google.com>]

Main changes since v5 [1]:
- Added handling of folio_put() when KVM is configured as a module
- KVM_GMEM_SHARED_MEM is orthogonal to KVM_GENERIC_MEMORY_ATTRIBUTES
  (Ackerley)
- kvm_gmem_offset_is_shared() takes folio as parameter to check locking
  (Kirill)
- Refactoring and fixes from comments on previous version
- Rebased on Linux 6.14-rc6

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
allows experimentation with what that support would be like in
the safe environment of software and non-confidential VM types.

For more background and for how to test this series, please refer
to v2 [3]. Note that an updated version of kvmtool that works
with this series is available here [4].

I'm working on respinning the series that tracks folio sharing [5]. I'll
post that one soon.

Cheers,
/fuad

[1] https://lore.kernel.org/all/20250303171013.3548775-1-tabba@google.com/
[2] https://lore.kernel.org/all/20250117163001.2326672-1-tabba@google.com/
[3] https://lore.kernel.org/all/20250129172320.950523-1-tabba@google.com/
[4] https://android-kvm.googlesource.com/kvmtool/+/refs/heads/tabba/guestmem-6.14
[5] https://lore.kernel.org/all/20250117163001.2326672-1-tabba@google.com/

Fuad Tabba (10):
  mm: Consolidate freeing of typed folios on final folio_put()
  KVM: guest_memfd: Handle final folio_put() of guest_memfd pages
  KVM: guest_memfd: Handle kvm_gmem_handle_folio_put() for KVM as a
    module
  KVM: guest_memfd: Allow host to map guest_memfd() pages
  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: Enable mapping guest_memfd in arm64
  KVM: guest_memfd: selftests: guest_memfd mmap() test when mapping is
    allowed

 arch/arm64/include/asm/kvm_host.h             |  10 ++
 arch/arm64/kvm/Kconfig                        |   1 +
 arch/arm64/kvm/mmu.c                          |  76 +++++++-----
 arch/x86/include/asm/kvm_host.h               |   5 +
 arch/x86/kvm/Kconfig                          |   3 +-
 include/linux/kvm_host.h                      |  23 +++-
 include/linux/page-flags.h                    |  31 +++++
 include/uapi/linux/kvm.h                      |   1 +
 mm/debug.c                                    |   1 +
 mm/swap.c                                     |  50 +++++++-
 tools/testing/selftests/kvm/Makefile.kvm      |   1 +
 .../testing/selftests/kvm/guest_memfd_test.c  |  75 +++++++++++-
 virt/kvm/Kconfig                              |   4 +
 virt/kvm/guest_memfd.c                        | 110 ++++++++++++++++++
 virt/kvm/kvm_main.c                           |   9 +-
 15 files changed, 354 insertions(+), 46 deletions(-)


base-commit: 80e54e84911a923c40d7bee33a34c1b4be148d7a
-- 
2.49.0.rc0.332.g42c0ae87b1-goog