Message-Id: <20220408210545.3915712-1-vannapurve@google.com>
Date:   Fri,  8 Apr 2022 21:05:40 +0000
From:   Vishal Annapurve <vannapurve@...gle.com>
To:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     pbonzini@...hat.com, vkuznets@...hat.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, shauh@...nel.org, yang.zhong@...el.com,
        drjones@...hat.com, ricarkol@...gle.com, aaronlewis@...gle.com,
        wei.w.wang@...el.com, kirill.shutemov@...ux.intel.com,
        corbet@....net, hughd@...gle.com, jlayton@...nel.org,
        bfields@...ldses.org, akpm@...ux-foundation.org,
        chao.p.peng@...ux.intel.com, yu.c.zhang@...ux.intel.com,
        jun.nakajima@...el.com, dave.hansen@...el.com,
        michael.roth@....com, qperret@...gle.com, steven.price@....com,
        ak@...ux.intel.com, david@...hat.com, luto@...nel.org,
        vbabka@...e.cz, marcorr@...gle.com, erdemaktas@...gle.com,
        pgonda@...gle.com, seanjc@...gle.com, diviness@...gle.com,
        Vishal Annapurve <vannapurve@...gle.com>
Subject: [RFC V1 PATCH 0/5] selftests: KVM: selftests for fd-based approach of
 supporting private memory

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

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

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