Patch "x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on CPUs without the feature" has been added to the 4.13-stable tree

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

x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on CPUs without the feature

to the 4.13-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-apic-silence-fw_bug-tsc_deadline-disabled-due-to-errata-on-cpus-without-the-feature.patch
and it can be found in the queue-4.13 subdirectory.

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

From: Hans de Goede <[email protected]>
Date: Wed, 30 Aug 2017 12:58:11 +0200
Subject: x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on CPUs without the feature

From: Hans de Goede <[email protected]>

commit 594a30fb12424717a41c62323d2a8bf167dbccad upstream.

When booting 4.13 on a VirtualBox VM on a Skylake host the following error shows up in the logs:

 [    0.000000] [Firmware Bug]: TSC_DEADLINE disabled due to Errata;
                please update microcode to version: 0xb2 (or later)

This is caused by apic_check_deadline_errata() only checking CPU model and not the X86_FEATURE_TSC_DEADLINE_TIMER flag (which VirtualBox does NOT export to the guest), combined with VirtualBox not exporting the micro-code version to the guest.

This commit adds a check for X86_FEATURE_TSC_DEADLINE_TIMER to apic_check_deadline_errata(), silencing this error on VirtualBox VMs.

---
 arch/x86/kernel/apic/apic.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

@@ -599,9 +599,13 @@ static const struct x86_cpu_id deadline_
 
 static void apic_check_deadline_errata(void)
 {
-	const struct x86_cpu_id *m = x86_match_cpu(deadline_match);
+	const struct x86_cpu_id *m;
 	u32 rev;
 
+	if (!boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
+		return;
+
+	m = x86_match_cpu(deadline_match);
 	if (!m)
 		return;
 

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

queue-4.13/x86-apic-silence-fw_bug-tsc_deadline-disabled-due-to-errata-on-hypervisors.patch queue-4.13/x86-apic-silence-fw_bug-tsc_deadline-disabled-due-to-errata-on-cpus-without-the-feature.patch