[v2,0/2] selftests: KVM: Add a test for eager page splitting

Message

Ben Gardon Jan. 23, 2023, 7:03 p.m. UTC

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.

V1->V2:
	Run test in multiple modes, as suggested by David and Ricardo
	Cleanups from shameful copy-pasta, as suggested by David

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     |   1 +
 .../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          | 278 ++++++++++++++++++
 7 files changed, 372 insertions(+), 77 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86_64/page_splitting_test.c