KVM: x86: Don't report guest userspace emulation error to
userspace (CVE-2014-7842 bnc#905312).
x86,kvm,vmx: Preserve CR4 across VM entry (CVE-2014-3690
bnc#902232).
kvm: fix excessive pages un-pinning in kvm_iommu_map error path
(CVE-2014-8369 bnc#902675).