linux-kernel - [PATCH 0/2] selftests: KVM: Add a test for eager page splitting

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Message-ID: <20230119212510.3938454-1-bgardon@google.com>
Date:   Thu, 19 Jan 2023 21:25:08 +0000
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Vipin Sharma <vipinsh@...gle.com>,
        Ricardo Koller <ricarkol@...gle.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 0/2] selftests: KVM: Add a test for eager page splitting

David Matlack recently added a feature known as eager page splitting
to x86 KVM. This feature improves vCPU performance during dirty
logging because the splitting operation is moved out of the page
fault path, avoiding EPT/NPT violations or allowing the vCPU threads
to resolve the violation in the fast path.

While this feature is a great performance improvement, it does not
have adequate testing in KVM selftests. Add a test to provide coverage
of eager page splitting.

Patch 1 is a quick refactor to be able to re-use some code from
dirty_log_perf_test.
Patch 2 adds the actual test.

Please ignore the RFC version of this series. It was not meant as an RFC
and did not include a cover letter.

Ben Gardon (2):
  selftests: KVM: Move dirty logging functions to memstress.(c|h)
  selftests: KVM: Add page splitting test

 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/dirty_log_perf_test.c       |  84 +----
 .../selftests/kvm/include/kvm_util_base.h     |   2 +
 .../testing/selftests/kvm/include/memstress.h |   8 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |   5 +
 tools/testing/selftests/kvm/lib/memstress.c   |  72 ++++
 .../kvm/x86_64/page_splitting_test.c          | 314 ++++++++++++++++++
 7 files changed, 409 insertions(+), 77 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86_64/page_splitting_test.c

-- 
2.39.1.405.gd4c25cc71f-goog