linux-kernel - [PATCH v7 15/16] x86/cpu/amd: Do not print FW

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Date: Wed, 20 Dec 2023 20:43:57 +0530
From: Nikunj A Dadhania <nikunj@....com>
To: <linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>,
	<x86@...nel.org>, <kvm@...r.kernel.org>
CC: <bp@...en8.de>, <mingo@...hat.com>, <tglx@...utronix.de>,
	<dave.hansen@...ux.intel.com>, <dionnaglaze@...gle.com>, <pgonda@...gle.com>,
	<seanjc@...gle.com>, <pbonzini@...hat.com>, <nikunj@....com>
Subject: [PATCH v7 15/16] x86/cpu/amd: Do not print FW_BUG for Secure TSC

When SecureTSC is enabled and TscInvariant (bit 8) in CPUID_8000_0007_edx
is set, kernel complains with the below firmware bug:

[Firmware Bug]: TSC doesn't count with P0 frequency!

Secure TSC need not run at P0 frequency, the TSC frequency is set by the
VMM as part of the SNP_LAUNCH_START command. Avoid the check when Secure
TSC is enabled

Signed-off-by: Nikunj A Dadhania <nikunj@....com>
Tested-by: Peter Gonda <pgonda@...gle.com>
---
 arch/x86/kernel/cpu/amd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index f322ebd053a9..b4a19e3fda8d 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -551,7 +551,8 @@ static void early_init_amd_mc(struct cpuinfo_x86 *c)
 
 static void bsp_init_amd(struct cpuinfo_x86 *c)
 {
-	if (cpu_has(c, X86_FEATURE_CONSTANT_TSC)) {
+	if (cpu_has(c, X86_FEATURE_CONSTANT_TSC) &&
+	    !cpu_feature_enabled(X86_FEATURE_SNP_SECURE_TSC)) {
 
 		if (c->x86 > 0x10 ||
 		    (c->x86 == 0x10 && c->x86_model >= 0x2)) {
-- 
2.34.1