2018-05-09 14:29-0700, Jim Mattson: > If there is a possibility that a VM may migrate to a Skylake host, > then the hypervisor should report IA32_ARCH_CAPABILITIES.RSBA[bit 2] > as being set (future work, of course). This implies that > CPUID.(EAX=7,ECX=0):EDX.ARCH_CAPABILITIES[bit 29] should be > set. Therefore, kvm should report this CPUID bit as being supported > whether or not the host supports it. Userspace is still free to clear > the bit if it chooses. > > For more information on RSBA, see Intel's white paper, "Retpoline: A > Branch Target Injection Mitigation" (Document Number 337131-001), > currently available at https://bugzilla.kernel.org/show_bug.cgi?id=199511. > > Since the IA32_ARCH_CAPABILITIES MSR is emulated in kvm, there is no > dependency on hardware support for this feature. > > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > --- Applied with Cc stable, thanks.
