Add a quirk to let userspace opt into correctly emulating MONITOR/MWAIT when they are disabled in CPUID instead of unconditionally treating them as NOPs. The selftest changes are based on the CPUID overhaul[*], the KVM patch should apply cleanly on kvm/queue, commit 55371f1d0c01 ("..."). Note! Patch 3 is a fix for a bug in the Hyper-V Features test that I encountered when verifying the exception fixup works as expected. The "bug", which is in reality a rather large set of bugs, basically turns the test into a giant nop. The patch really should be "backported" all the way across the selftests overhaul, but I don't care enough about Hyper-V to spend yet more time on selftests at this point. [*] https://lore.kernel.org/all/20220604012058.1972195-1-seanjc@xxxxxxxxxx Sean Christopherson (5): KVM: x86: Add a quirk for KVM's "MONITOR/MWAIT are NOPs!" behavior KVM: selftests: Add x86-64 support for exception fixup KVM: selftests: Mostly fix comically broken Hyper-V Features test KVM: selftests: Use exception fixup for #UD/#GP Hyper-V MSR/hcall tests KVM: selftests: Add MONITOR/MWAIT quirk test Documentation/virt/kvm/api.rst | 13 + arch/x86/include/asm/kvm_host.h | 3 +- arch/x86/include/uapi/asm/kvm.h | 1 + arch/x86/kvm/x86.c | 26 +- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/x86_64/processor.h | 74 ++++++ .../selftests/kvm/lib/x86_64/processor.c | 17 ++ .../selftests/kvm/x86_64/hyperv_features.c | 239 ++++++++---------- .../selftests/kvm/x86_64/kvm_pv_test.c | 82 ++---- .../selftests/kvm/x86_64/monitor_mwait_test.c | 127 ++++++++++ 11 files changed, 375 insertions(+), 209 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c base-commit: 081ad4bbae8d503c79fae45f463766d28b2f3241 -- 2.36.1.255.ge46751e96f-goog