[PATCH v3 0/9] liveupdate: kvm: guest_memfd preservation

[tarunsahu at google.com]

+ Adding More people to the series (To:) which I missed in my original message.

~Tarun

Tarun Sahu <tarunsahu at google.com> writes:

> Hello,
> This is Non-RFC patch series for guest_memfd preservation. After
> having multiple discussion across hypervisor liveupdate meeting,
> guest_memfd bi-weekly meeting, the design for the basic support of
> guest_memfd preservation is final. This series is going to include
> guest_memfd which are fully shared and does not support private mem
> and backed by PAGE_SIZE pages.
>
> Steps to test:
> 1. Compile Kernel with CONFIG_LIVEUPDATE_GUEST_MEMFD=y
> 2. boot kernel with command line: kho=on liveupdate=on
> 3. run the following kselftest
> 	$ .selftests/kvm/guest_memfd_preservation_test --stage 1
> 	$ <kexec> --reuse-cmdline
> 	$ .selftests/kvm/guest_memfd_preservation_test --stage 2
>
> NOTE: Assert the following:
> 	$ ls /dev/liveupdate
> 	$ ls /dev/kvm
> 	$ dmesg | grep liveupdate # (should have kvm_vm_luo &&
> 		# guest_memfd_luo handler registered)
>
> The changes are rebased on:
> 	kvm/next + liveupdate/next (merge) + [3] + [4] + [5]
> 	Where,
> 	[3]: luo: conversion of serialized_data to KHOSER_PTR
> 	[4]: luo: APIs to retrieve file internally from session
> 	[5]: selftests: liveupdate sefltests library
> Here is the github repo:
> 	https://github.com/tar-unix/linux/tree/gmem-pre
>
> V3 <- RFC V2 [2]
> 1. Finalize the design
> 2. resolve sashiko reported bugs
> 3. Use of KHOSER_PTR instead of raw serialized_data as per [3]
>
> RFC V2 [2] <- RFC V1 [1]
> 1. Removed mem_attr_array as it is not needed for fully-shared
> 2. Removed pre-faulted condition
> 3. Added vm_type preservation for ARM64.
> 4. Removed liveupdate_get_file_incoming api patch as it is sent
>    separately [4] by Samiullah.
>
> [1] https://lore.kernel.org/all/cover.1779080766.git.tarunsahu@google.com/
> [2] https://lore.kernel.org/all/c054ba0fb2639932bbe354420d3f4f84cce84905.1780676742.git.tarunsahu@google.com/
> [3] https://lore.kernel.org/all/20260622111215.4157974-1-tarunsahu@google.com/
> [4] https://lore.kernel.org/all/20260613012521.835490-1-skhawaja@google.com/
> [5] https://lore.kernel.org/all/20260612214512.464146-1-vipinsh@google.com/
>
> Tarun Sahu (9):
>   liveupdate: Add LIVEUPDATE_GUEST_MEMFD config option
>   kvm: Prepare core VM structs and helpers for LUO support
>   kvm: kvm_luo: Allow kvm preservation with LUO
>   kvm: guest_memfd: Move internal definitions and helper to new header
>   kvm: guest_memfd: Add support for freezing and unfreezing mappings
>   kvm: guest_memfd_luo: add support for guest_memfd preservation
>   docs: add documentation for guest_memfd preservation via LUO
>   selftests: kvm: Split ____vm_create() to expose init helpers
>   selftests: kvm: Add guest_memfd_preservation_test
>
>  Documentation/core-api/liveupdate.rst         |   1 +
>  Documentation/liveupdate/vmm.rst              | 107 ++++
>  MAINTAINERS                                   |  14 +
>  include/linux/kho/abi/kvm.h                   | 106 ++++
>  include/linux/kvm_host.h                      |  14 +
>  kernel/liveupdate/Kconfig                     |  15 +
>  tools/testing/selftests/kvm/Makefile.kvm      |   6 +-
>  .../kvm/guest_memfd_preservation_test.c       | 236 +++++++++
>  .../testing/selftests/kvm/include/kvm_util.h  |   2 +
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  26 +-
>  virt/kvm/Makefile.kvm                         |   1 +
>  virt/kvm/guest_memfd.c                        | 185 +++++--
>  virt/kvm/guest_memfd.h                        |  44 ++
>  virt/kvm/guest_memfd_luo.c                    | 497 ++++++++++++++++++
>  virt/kvm/kvm_luo.c                            | 195 +++++++
>  virt/kvm/kvm_main.c                           |  94 +++-
>  virt/kvm/kvm_mm.h                             |  15 +
>  17 files changed, 1477 insertions(+), 81 deletions(-)
>  create mode 100644 Documentation/liveupdate/vmm.rst
>  create mode 100644 include/linux/kho/abi/kvm.h
>  create mode 100644 tools/testing/selftests/kvm/guest_memfd_preservation_test.c
>  create mode 100644 virt/kvm/guest_memfd.h
>  create mode 100644 virt/kvm/guest_memfd_luo.c
>  create mode 100644 virt/kvm/kvm_luo.c
>
> -- 
> 2.55.0.rc0.786.g65d90a0328-goog