From: Konrad Rzeszutek Wilk konrad.wilk@oracle.com

commit 36268223c1e9981d6cfc33aff8520b3bde4b8114 upstream.

As:

1) It's known that hypervisors lie about the environment anyhow (host mismatch)

2) Even if the hypervisor (Xen, KVM, VMWare, etc) provided a valid "correct" value, it all gets to be very murky when migration happens (do you provide the "new" microcode of the machine?).

And in reality the cloud vendors are the ones that should make sure that the microcode that is running is correct and we should just sing lalalala and trust them.

Signed-off-by: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Paolo Bonzini pbonzini@redhat.com Cc: Wanpeng Li kernellwp@gmail.com Cc: kvm kvm@vger.kernel.org Cc: Krčmář rkrcmar@redhat.com Cc: Borislav Petkov bp@alien8.de CC: "H. Peter Anvin" hpa@zytor.com CC: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180226213019.GE9497@char.us.oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [Yi Sun: cherry pick to 4.4] Signed-off-by: Yi Sun yi.y.sun@linux.intel.com --- arch/x86/kernel/cpu/intel.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index af28610..221c030 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -71,6 +71,13 @@ static bool bad_spectre_microcode(struct cpuinfo_x86 *c) { int i;

+ /* + * We know that the hypervisor lie to us on the microcode version so + * we may as well hope that it is running the correct version. + */ + if (cpu_has(c, X86_FEATURE_HYPERVISOR)) + return false; + for (i = 0; i < ARRAY_SIZE(spectre_bad_microcodes); i++) { if (c->x86_model == spectre_bad_microcodes[i].model && c->x86_mask == spectre_bad_microcodes[i].stepping)