Use guest mem inodes instead of anonymous inodes

Hi,

This small patch series makes guest_memfd use guest mem inodes instead of anonymous inodes and also includes some refactoring to expose a new function that allocates an inode and runs security checks.

This patch series will serve as a common base for some in-flight series:

* Add NUMA mempolicy support for KVM guest-memfd [1]
* New KVM ioctl to link a gmem inode to a new gmem file [2]
* Restricted mapping of guest_memfd at the host and arm64 support [3] aka shared/private conversion support for guest_memfd

[1] https://lore.kernel.org/all/[email protected]/
[2] https://lore.kernel.org/lkml/[email protected]/
[3] https://lore.kernel.org/all/[email protected]/

Ackerley Tng (2):
fs: Provide function that allocates a secure anonymous inode
KVM: guest_memfd: Use guest mem inodes instead of anonymous inodes

 fs/anon_inodes.c           |  22 ++++--
 include/linux/fs.h         |   1 +
 include/uapi/linux/magic.h |   1 +
 mm/secretmem.c             |   9 +--
 virt/kvm/guest_memfd.c     | 134 +++++++++++++++++++++++++++++++------
 virt/kvm/kvm_main.c        |   7 +-
 virt/kvm/kvm_mm.h          |   9 ++-
 7 files changed, 143 insertions(+), 40 deletions(-)

base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21 --
2.49.0.1204.g71687c7c1d-goog