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

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Date:   Wed,  8 Jun 2022 22:45:11 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 0/5] KVM: x86: Quirk "MWAIT never faults" behavior

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