[RFC,v2,0/2] KVM: guest_memfd: use write for population

Message

Nikita Kalyazin Nov. 29, 2024, 12:39 p.m. UTC

As discussed in the v1 [1], with guest_memfd moving from KVM to mm, it
is more practical to have a non-KVM-specific API to populate guest
memory in a generic way.  The series proposes using the write syscall
for this purpose instead of a KVM ioctl as in the v1.  The approach also
has an advantage that the guest_memfd handle can be sent to another
process that would be responsible for population.  I also included a
suggestion from Mike Day for excluding the code from compilation if AMD
SEV is configured.

There is a potential for refactoring of the kvm_gmem_populate to extract
common parts with the write.  I did not do that in this series yet to
keep it clear what the write would do and get feedback on whether
write's behaviour is sensible.

Nikita

[1]: https://lore.kernel.org/kvm/[e-mail]/T/

Nikita Kalyazin (2):
  KVM: guest_memfd: add generic population via write
  KVM: selftests: update guest_memfd write tests

 .../testing/selftests/kvm/guest_memfd_test.c  | 85 +++++++++++++++++--
 virt/kvm/guest_memfd.c                        | 79 +++++++++++++++++
 2 files changed, 158 insertions(+), 6 deletions(-)


base-commit: 1508bae37044ebffd7c7e09915f041936f338123