[PATCH v7 0/9] KVM: Mapping guest_memfd backed memory at the host for software protected VMs

[Fuad Tabba <tabba@google.com>]

Main changes since v6 [1]:
- Fix and simplify handling of final folio_put() callback in case
  underlying file is no longer associated with guestmem, e.g., KVM
  module unloaded (Ackerley, Vlastimil)
- Removed dependency on folio lock when not needed (Ackerley)
- Carried acks (DavidH, Vlastimil)
- Rebased on Linux 6.14-rc7

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 done respinning the series that tracks folio sharing [5]. I'll post
that one right after this one.

Cheers,
/fuad

[1] https://lore.kernel.org/all/20250312175824.1809636-1-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 (9):
  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: 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             |  12 ++
 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                                     |  52 ++++++++-
 tools/testing/selftests/kvm/Makefile.kvm      |   1 +
 .../testing/selftests/kvm/guest_memfd_test.c  |  75 +++++++++++-
 virt/kvm/Kconfig                              |   4 +
 virt/kvm/guest_memfd.c                        | 109 ++++++++++++++++++
 virt/kvm/kvm_main.c                           |   9 +-
 15 files changed, 357 insertions(+), 46 deletions(-)


base-commit: 4701f33a10702d5fc577c32434eb62adde0a1ae1
-- 
2.49.0.rc1.451.g8f38331e32-goog