Patch "x86/spectre_v2: Don't check microcode versions when running under hypervisors" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-spectre_v2-don-t-check-microcode-versions-when-running-under-hypervisors.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Konrad Rzeszutek Wilk <[email protected]>
Date: Mon, 26 Feb 2018 09:35:01 -0500
Subject: x86/spectre_v2: Don't check microcode versions when running under hypervisors
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From: Konrad Rzeszutek Wilk <[email protected]>

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.

---
 arch/x86/kernel/cpu/intel.c |    7 +++++++
 1 file changed, 7 insertions(+)

@@ -144,6 +144,13 @@ static bool bad_spectre_microcode(struct
 {
 	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_stepping == spectre_bad_microcodes[i].stepping)

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-spectre_v2-don-t-check-microcode-versions-when-running-under-hypervisors.patch