[PATCH 0/5] KVM: x86: Quirk "MWAIT never faults" behavior

Sean Christopherson
2022-06-08T22:45:29Z

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@google.com

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