[PATCH v10 00/41] guest_memfd: In-place conversion support

This is v10 of guest_memfd in-place conversion support, which addresses
comments on v9. Please find the motivation for this series from v8 and
before.

v9 is based on kvm-x86/next, with a cherry-picked version of David's GUP
fix [1], and a cherry-picked version of David's refactoring patch
[2].

Here's everything stitched together for your convenience:

https://github.com/googleprodkernel/linux-cc/commits/guest_memfd-inplace-conversion-v10

I tested v10 with CoCo selftests on top of the branch above:

https://github.com/googleprodkernel/linux-cc/commits/guest_memfd-inplace-conversion-coco-selftests-v10

Tested with both CONFIG_KVM_VM_MEMORY_ATTRIBUTES enabled and disabled:

+ tools/testing/selftests/kvm/guest_memfd_test.c
+ tools/testing/selftests/kvm/pre_fault_memory_test.c
+ tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c
+ tools/testing/selftests/kvm/x86/private_mem_conversions_test.c
+ tools/testing/selftests/kvm/x86/private_mem_kvm_exits_test.c
+ The TDX and SNP conversions selftests in https://github.com/googleprodkernel/linux-cc/commits/guest_memfd-inplace-conversion-coco-selftests-v10

[1] https://lore.kernel.org/all/20260731-check_and_migrate_movable_folios-v1-1-e0002d7b791e@kernel.org/ (local)
("mm/gup: fix always draining LRU caches in collect_longterm_unpinnable_folios()")
[2] https://lore.kernel.org/all/20260806-lru_cache_drain_for_folio-v1-1-c6287d295e99@kernel.org/ (local)
("mm/gup: factor out LRU cache draining for folio into lru_cache_drain_for_folio()")

Older series:

v9: https://lore.kernel.org/r/20260728-gmem-inplace-conversion-v9-0-35f9aec2aed2@google.com (local)
v8: https://lore.kernel.org/r/20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com (local)
v7: https://lore.kernel.org/r/20260522-gmem-inplace-conversion-v7-0-2f0fae496530@google.com (local)
v6: https://lore.kernel.org/r/20260507-gmem-inplace-conversion-v6-0-91ab5a8b19a4@google.com (local)
RFC v5: https://lore.kernel.org/r/20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@google.com (local)
RFC v4: https://lore.kernel.org/all/20260326-gmem-inplace-conversion-v4-0-e202fe950ffd@google.com/T/ (local)
RFC v3: https://lore.kernel.org/r/20260313-gmem-inplace-conversion-v3-0-5fc12a70ec89@google.com/T/ (local)
RFC v2: https://lore.kernel.org/all/cover.1770071243.git.ackerleytng@google.com/T/ (local)
RFC v1: https://lore.kernel.org/all/cover.1760731772.git.ackerleytng@google.com/T/ (local)

Previous versions of this feature, part of other series, are available at:

+ https://lore.kernel.org/all/bd163de3118b626d1005aa88e71ef2fb72f0be0f.1726009989.git.ackerleytng@google.com/ (local)
+ https://lore.kernel.org/all/20250117163001.2326672-6-tabba@google.com/ (local)
+ https://lore.kernel.org/all/b784326e9ccae6a08388f1bf39db70a2204bdc51.1747264138.git.ackerleytng@google.com/ (local)

Signed-off-by: Ackerley Tng <redacted>
---
Ackerley Tng (21):
      KVM: guest_memfd: Filter both shared and private when invalidating
      KVM: guest_memfd: Add base support for KVM_SET_MEMORY_ATTRIBUTES2
      KVM: guest_memfd: Ensure pages are not in use before conversion
      KVM: guest_memfd: Call arch make_shared callback for to-shared conversion
      KVM: guest_memfd: Return early if range already has requested attributes
      KVM: guest_memfd: Handle lru_add fbatch refcounts during conversion safety check
      KVM: guest_memfd: Zero page while getting pfn
      KVM: TDX: Make source page optional for KVM_TDX_INIT_MEM_REGION
      KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes
      KVM: selftests: Test basic single-page conversion flow
      KVM: selftests: Test conversion flow when INIT_SHARED
      KVM: selftests: Test conversion precision in guest_memfd
      KVM: selftests: Test conversion before allocation
      KVM: selftests: Convert with allocated folios in different layouts
      KVM: selftests: Test that truncation does not change shared/private status
      KVM: selftests: Add helpers to pin pages with CONFIG_GUP_TEST
      KVM: selftests: Test conversion with elevated page refcount
      KVM: selftests: Reset shared memory after hole-punching
      KVM: selftests: Provide function to look up guest_memfd details from gpa
      KVM: selftests: Make TEST_EXPECT_SIGBUS thread-safe
      KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd

David Hildenbrand (Arm) (1):
      mm/gup: factor out LRU cache draining for folio into lru_cache_drain_for_folio()

Michael Roth (1):
      KVM: SEV: Make 'uaddr' parameter optional for KVM_SEV_SNP_LAUNCH_UPDATE

Sean Christopherson (18):
      KVM: guest_memfd: Use kvm_mem_is_private() when populating guest_memfd memory
      KVM: guest_memfd: Introduce per-gmem attributes, use to guard user mappings
      KVM: Rename KVM_GENERIC_MEMORY_ATTRIBUTES to KVM_VM_MEMORY_ATTRIBUTES
      KVM: Enumerate support for PRIVATE memory iff kvm_arch_has_private_mem is defined
      KVM: Rename memory attribute APIs to prepare for in-place gmem conversion
      KVM: Provide generic interface for checking memory private/shared status
      KVM: guest_memfd: Stub in ability to enable in-place shared<=>private conversion
      KVM: Consolidate private memory and guest_memfd ifdeffery in kvm_host.h
      KVM: Move KVM_VM_MEMORY_ATTRIBUTES config definition to x86
      KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs
      KVM: selftests: Create gmem fd before "regular" fd when adding memslot
      KVM: selftests: Rename guest_memfd{,_offset} to gmem_{fd,offset}
      KVM: selftests: Add support for mmap() on guest_memfd in core library
      KVM: selftests: Add selftests global for guest memory attributes capability
      KVM: selftests: Add helpers for calling ioctls on guest_memfd
      KVM: selftests: Test that shared/private status is consistent across processes
      KVM: selftests: Provide common function to set memory attributes
      KVM: selftests: Update private memory exits test to work with per-gmem attributes

 Documentation/virt/kvm/api.rst                     |  78 +++-
 .../virt/kvm/x86/amd-memory-encryption.rst         |  14 +-
 Documentation/virt/kvm/x86/intel-tdx.rst           |   4 +
 arch/x86/include/asm/kvm-x86-ops.h                 |   2 +-
 arch/x86/include/asm/kvm_host.h                    |   6 +-
 arch/x86/kvm/Kconfig                               |  15 +-
 arch/x86/kvm/mmu/mmu.c                             |  16 +-
 arch/x86/kvm/svm/sev.c                             |  11 +-
 arch/x86/kvm/vmx/tdx.c                             |   8 +-
 arch/x86/kvm/x86.c                                 |  20 +-
 include/linux/kvm_host.h                           |  76 +--
 include/linux/swap.h                               |  11 +-
 include/trace/events/kvm.h                         |   6 +-
 include/uapi/linux/kvm.h                           |  16 +
 mm/gup.c                                           |  15 +-
 mm/swap.c                                          |  48 ++
 tools/testing/selftests/kvm/Makefile.kvm           |   1 +
 tools/testing/selftests/kvm/include/kvm_util.h     | 139 +++++-
 tools/testing/selftests/kvm/include/test_util.h    |  34 +-
 tools/testing/selftests/kvm/lib/kvm_util.c         | 164 ++++---
 tools/testing/selftests/kvm/lib/test_util.c        |   7 -
 .../kvm/x86/guest_memfd_conversions_test.c         | 512 +++++++++++++++++++++
 .../kvm/x86/private_mem_conversions_test.c         |  53 ++-
 .../selftests/kvm/x86/private_mem_kvm_exits_test.c |  36 +-
 virt/kvm/Kconfig                                   |   3 -
 virt/kvm/guest_memfd.c                             | 450 ++++++++++++++++--
 virt/kvm/kvm_main.c                                |  92 ++--
 27 files changed, 1574 insertions(+), 263 deletions(-)
---
base-commit: 4217d4987bbe33e331764a752721f781123b2e07
change-id: 20260225-gmem-inplace-conversion-bd0dbd39753a

Best regards,
--
Ackerley Tng [off-list ref]