Commit 36268223 authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk Committed by Thomas Gleixner

x86/spectre_v2: Don't check microcode versions when running under hypervisors

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: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarPaolo 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
parent 076ca272
...@@ -144,6 +144,13 @@ static bool bad_spectre_microcode(struct cpuinfo_x86 *c) ...@@ -144,6 +144,13 @@ static bool bad_spectre_microcode(struct cpuinfo_x86 *c)
{ {
int i; 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++) { for (i = 0; i < ARRAY_SIZE(spectre_bad_microcodes); i++) {
if (c->x86_model == spectre_bad_microcodes[i].model && if (c->x86_model == spectre_bad_microcodes[i].model &&
c->x86_stepping == spectre_bad_microcodes[i].stepping) c->x86_stepping == spectre_bad_microcodes[i].stepping)
......
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