kvm/split_lock: Add feature split lock detection support in kvm

This version adds the virtualization of split lock detection for guest
in patch 5 and patch 6.

No matter whether we advertise split lock detection to guest, we have to make
a choice between not burn the old guest and prevent DoS attack from guest since
we cannot identify whether a guest is malicious.

Since sld_warn mode also allows userspace applications to do split lock
we can extend the similar policy to guest that if host is sld_warn, we allow
guest to generate split lock by clearing MSR_TEST_CTRL.SPLIT_LOCK_DETECT bit
when vcpu is running.

If host is sld_fatal mode and guest doesn't set its SPLIT_LOCK_DETECT bit we
forward split lock #AC to user space, similar as sending SIGBUS.

Xiaoyao Li (6):
  x86/split_lock: Add and export get_split_lock_detect_state()
  x86/split_lock: Add and export split_lock_detect_set()
  kvm: x86: Emulate split-lock access as a write
  kvm: vmx: Extend VMX's #AC handding for split lock in guest
  kvm: x86: Emulate MSR IA32_CORE_CAPABILITIES
  x86: vmx: virtualize split lock detection

 arch/x86/include/asm/cpu.h      | 13 +++++
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kernel/cpu/intel.c     | 18 ++++--
 arch/x86/kvm/cpuid.c            |  5 +-
 arch/x86/kvm/vmx/vmx.c          | 98 ++++++++++++++++++++++++++++++++-
 arch/x86/kvm/vmx/vmx.h          |  4 ++
 arch/x86/kvm/x86.c              | 44 ++++++++++++++-
 7 files changed, 171 insertions(+), 12 deletions(-)

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2.23.0