x86/feature: Enable the x86 feature to control Speculation
CVE-2017-5753
CVE-2017-5715
cpuid ax=0x7, return rdx bit 26 to indicate presence of this feature
IA32_SPEC_CTRL (0x48) and IA32_PRED_CMD (0x49)
IA32_SPEC_CTRL, bit0 – Indirect Branch Restricted Speculation (IBRS)
IA32_PRED_CMD, bit0 – Indirect Branch Prediction Barrier (IBPB)
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Andy Whitcroft <apw@canonical.com> Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>