[RFC V1 PATCH 0/5] selftests: KVM: selftests for fd-based approach of supporting private memory

[Vishal Annapurve]

This series implements selftests targeting the feature floated by Chao
via:
https://lore.kernel.org/linux-mm/20220310140911.50924-1-chao.p.peng@xxxxxxxxxxxxxxx/

Below changes aim to test the fd based approach for guest private memory
in context of normal (non-confidential) VMs executing on non-confidential
platforms.

Confidential platforms along with the confidentiality aware software
stack support a notion of private/shared accesses from the confidential
VMs.
Generally, a bit in the GPA conveys the shared/private-ness of the
access. Non-confidential platforms don't have a notion of private or
shared accesses from the guest VMs. To support this notion,
KVM_HC_MAP_GPA_RANGE
is modified to allow marking an access from a VM within a GPA range as
always shared or private. Any suggestions regarding implementing this ioctl
alternatively/cleanly are appreciated.

priv_memfd_test.c file adds a suite of two basic selftests to access private
memory from the guest via private/shared access and checking if the contents
can be leaked to/accessed by vmm via shared memory view.

Test results:
1) PMPAT - PrivateMemoryPrivateAccess test passes
2) PMSAT - PrivateMemorySharedAccess test fails currently and needs more
analysis to understand the reason of failure.

Important - Below patch is needed to ensure host kernel crash is avoided while
running these tests:
https://github.com/vishals4gh/linux/commit/b9adedf777ad84af39042e9c19899600a4add68a

Github link for the patches posted as part of this series:
https://github.com/vishals4gh/linux/commits/priv_memfd_selftests_v1
Note that this series is dependent on Chao's v5 patches mentioned above
applied on top of 5.17.

Vishal Annapurve (5):
  x86: kvm: HACK: Allow testing of priv memfd approach
  selftests: kvm: Fix inline assembly for hypercall
  selftests: kvm: Add a basic selftest test priv memfd
  selftests: kvm: priv_memfd_test: Add support for memory conversion
  selftests: kvm: priv_memfd_test: Add shared access test

 arch/x86/include/uapi/asm/kvm_para.h          |   1 +
 arch/x86/kvm/mmu/mmu.c                        |   9 +-
 arch/x86/kvm/x86.c                            |  16 +-
 include/linux/kvm_host.h                      |   3 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/lib/x86_64/processor.c      |   2 +-
 tools/testing/selftests/kvm/priv_memfd_test.c | 410 ++++++++++++++++++
 virt/kvm/kvm_main.c                           |   2 +-
 8 files changed, 436 insertions(+), 8 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/priv_memfd_test.c

-- 
2.35.1.1178.g4f1659d476-goog