[artful][PATCH 1/2] x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on CPUs without the feature

Dan Streetman dan.streetman at canonical.com
Thu Oct 19 20:11:41 UTC 2017

From: Hans de Goede <hdegoede at redhat.com>

BugLink: http://bugs.launchpad.net/bugs/1724912

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.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
Acked-by: Thomas Gleixner <tglx at linutronix.de>
Cc: Frank Mehnert <frank.mehnert at oracle.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Michael Thayer <michael.thayer at oracle.com>
Cc: Michal Necasek <michal.necasek at oracle.com>
Cc: Peter Zijlstra <peterz at infradead.org>
Fixes: bd9240a18e ("x86/apic: Add TSC_DEADLINE quirk due to errata")
Link: http://lkml.kernel.org/r/20170830105811.27539-1-hdegoede@redhat.com
Signed-off-by: Ingo Molnar <mingo at kernel.org>
(cherry-picked from commit 594a30fb12424717a41c62323d2a8bf167dbccad upstream)
Signed-off-by: Dan Streetman <dan.streetman at canonical.com>

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

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 98b3dd8cf2bf..b3273c842850 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -599,9 +599,13 @@ static const struct x86_cpu_id deadline_match[] = {
 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)

More information about the kernel-team mailing list