[PATCH v2 0/4] Verify dirty logging works properly with page stats

[Mingwei Zhang]

This patchset is to verify if dirty logging works properly by checking page
stats from the per-VM interface. We discovered one performance bug in
disallowed_hugepage_adjust() which prevents KVM from recovering large pages
for the guest. The selftest logic added later could help validate the
problem.

The patchset borrowes two patches come from Ben's series: "[PATCH 00/13]
KVM: x86: Add a cap to disable NX hugepages on a VM" [1], which completes
the selftest library functions to use the stats interface.

[1] https://lore.kernel.org/all/20220310164532.1821490-2-bgardon@xxxxxxxxxx/T/

v2 -> v1:
 - Update the commit message. [dmatlack]
 - Update the comments in patch 3/4 to clarify the motivation. [bgardon]
 - Add another iteration in dirty_log_perf_test to regain pages [bgardon]

v1: https://lore.kernel.org/all/20220321002638.379672-1-mizhang@xxxxxxxxxx/

Ben Gardon (2):
  selftests: KVM: Dump VM stats in binary stats test
  selftests: KVM: Test reading a single stat

Mingwei Zhang (2):
  KVM: x86/mmu: explicitly check nx_hugepage in
    disallowed_hugepage_adjust()
  selftests: KVM: use dirty logging to check if page stats work
    correctly

 arch/x86/kvm/mmu/mmu.c                        |  14 +-
 .../selftests/kvm/dirty_log_perf_test.c       |  53 +++++
 .../selftests/kvm/include/kvm_util_base.h     |   2 +
 .../selftests/kvm/kvm_binary_stats_test.c     |   6 +
 tools/testing/selftests/kvm/lib/kvm_util.c    | 196 ++++++++++++++++++
 5 files changed, 269 insertions(+), 2 deletions(-)

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2.35.1.1021.g381101b075-goog