kvm: vmx: add MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD

kvm: vmx: add MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD

[RHEL7.5 PATCH 08/35] kvm: vmx: add MSR_IA32_SPEC_CTRL and
 MSR_IA32_PRED_CMD

Allow load/store of MSR_IA32_SPEC_CTRL, restore guest IBRS on VM entry
and set it to 1 on VM exit.

Orabug: 27344012
CVE: CVE-2017-5715

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: John Haxby <john.haxby@oracle.com>
Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>