Security update for kvm (important)

This update for kvm fixes the following issues:

• This update has the next round of Spectre v2 related patches, which now
  integrates with corresponding changes in libvirt. A January 2018 release
  of qemu initially addressed the Spectre v2 vulnerability for KVM guests
  by exposing the spec-ctrl feature for all x86 vcpu types, which was the
  quick and dirty approach, but not the proper solution. We remove that
  initial patch and now rely on patches from upstream. This update defines
  spec_ctrl and ibpb cpu feature flags as well as new cpu models which are
  clones
  of existing models with either -IBRS or -IBPB added to the end of the
  model name. These new vcpu models explicitly include the new
  feature(s), whereas the feature flags can be added to the cpu parameter
  as with other features. In short, for continued Spectre v2 protection,
  ensure that either the appropriate cpu feature flag is added to the
  QEMU command-line, or one of the new cpu models is used. Although
  migration from older versions is supported, the new cpu features won’t
  be properly exposed to the guest until it is restarted with the cpu
  features explicitly added. A reboot is insufficient.

• A warning patch is added which attempts to detect a migration from a
  qemu version which had the quick and dirty fix (it only detects certain
  cases, but hopefully is helpful.) For additional information on Spectre
  v2 as it relates to QEMU, see:
  <a href=“https://www.qemu.org/2018/02/14/qemu-2-11-1-and-spectre-update/”>https://www.qemu.org/2018/02/14/qemu-2-11-1-and-spectre-update/</a>
  (CVE-2017-5715 bsc#1068032)

• A patch is added to continue to detect Spectre v2 mitigation features
  (as shown by cpuid), and if found provide that feature to guests, even
  if running on older KVM (kernel) versions which do not yet expose that
  feature to QEMU. (bsc#1082276) These two patches will be removed when we
  can reasonably assume everyone is running with the appropriate updates.

• Security fixes for the following CVE issues: (bsc#1076114 CVE-2018-5683)
  (bsc#1083291 CVE-2018-7550)

• This patch is already included, add here for CVE track (bsc#1076179
  CVE-2017-18030)

• Toolchain changes have cause the built size of pxe-virtio.rom to exceed
  64K. Tweak rarely used strings in code to reduce size of the binary so
  it fits again.

• Eliminate bogus use of CPUID_7_0_EDX_PRED_CMD which we’ve carried since
  the initial Spectre v2 patch was added. EDX bit 27 of CPUID Leaf 07H,
  Sub-leaf 0 provides status on STIBP, and not the PRED_CMD MSR. Exposing
  the STIBP CPUID feature bit to the guest is wrong in general, since the
  VM doesn’t directly control the scheduling of physical hyperthreads.
  This is left strictly to the L0 hypervisor.