Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Certain AMD processors are vulnerable to a cross-thread return address
  predictions bug. When running in SMT mode and one of the sibling
  threads transitions out of C0 state, the other thread gets access to
  twice as many entries in the RSB, but unfortunately the predictions of
  the now-halted logical processor are not purged. Therefore, the
  executing processor could speculatively execute from locations that
  the now-halted processor had trained the RSB on.

  The Spectre v2 mitigations cover the Linux kernel, as it fills the RSB
  when context switching to the idle thread. However, KVM allows a VMM
  to prevent exiting guest mode when transitioning out of C0 using the
  KVM_CAP_X86_DISABLE_EXITS capability can be used by a VMM to change
  this behavior. To mitigate the cross-thread return address predictions
  bug, a VMM must not be allowed to override the default behavior to
  intercept C0 transitions.

  These patches introduce a KVM module parameter that, if set, will
  prevent the user from disabling the HLT, MWAIT and CSTATE exits"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  Documentation/hw-vuln: Add documentation for Cross-Thread Return Predictions
  KVM: x86: Mitigate the cross-thread return address predictions bug
  x86/speculation: Identify processors vulnerable to SMT RSB predictions