linux-kernel - [PATCH 4.13 02/11] x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on hypervisors

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Message-Id: <20171019131659.709398710@linuxfoundation.org>
Date:   Thu, 19 Oct 2017 15:38:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Hans de Goede <hdegoede@...hat.com>, kvm@...r.kernel.org
Subject: [PATCH 4.13 02/11] x86/apic: Silence "FW_BUG TSC_DEADLINE disabled due to Errata" on hypervisors

4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paolo Bonzini <pbonzini@...hat.com>

commit cc6afe2240298049585e86b1ade85efc8a7f225d upstream.

Commit 594a30fb1242 ("x86/apic: Silence "FW_BUG TSC_DEADLINE disabled
due to Errata" on CPUs without the feature", 2017-08-30) was also about
silencing the warning on VirtualBox; however, KVM does expose the TSC
deadline timer, and it's virtualized so that it is immune from CPU errata.

Therefore, booting 4.13 with "-cpu Haswell" shows this in the logs:

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

Even if you had a hypervisor that does _not_ virtualize the TSC deadline
and rather exposes the hardware one, it should be the hypervisors task
to update microcode and possibly hide the flag from CPUID.  So just
hide the message when running on _any_ hypervisor, not just those that
do not support the TSC deadline timer.

The older check still makes sense, so keep it.

Fixes: bd9240a18e ("x86/apic: Add TSC_DEADLINE quirk due to errata")
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Hans de Goede <hdegoede@...hat.com>
Cc: kvm@...r.kernel.org
Link: https://lkml.kernel.org/r/1507630377-54471-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kernel/apic/apic.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -602,7 +602,8 @@ static void apic_check_deadline_errata(v
 	const struct x86_cpu_id *m;
 	u32 rev;

-	if (!boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
+	if (!boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER) ||
+	    boot_cpu_has(X86_FEATURE_HYPERVISOR))
 		return;

 	m = x86_match_cpu(deadline_match);