linux-kernel - [PATCH v9 21/24] x86/kvmclock: Skip kvmclock when Secure TSC is available

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Message-ID: <20240531043038.3370793-22-nikunj@amd.com>
Date: Fri, 31 May 2024 10:00:35 +0530
From: Nikunj A Dadhania <nikunj@....com>
To: <linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>, <bp@...en8.de>,
	<x86@...nel.org>, <kvm@...r.kernel.org>
CC: <mingo@...hat.com>, <tglx@...utronix.de>, <dave.hansen@...ux.intel.com>,
	<pgonda@...gle.com>, <seanjc@...gle.com>, <pbonzini@...hat.com>,
	<nikunj@....com>
Subject: [PATCH v9 21/24] x86/kvmclock: Skip kvmclock when Secure TSC is available

For AMD SNP guests having Secure TSC enabled, skip using the kvmclock.
The guest kernel will fallback and use Secure TSC based clocksource.

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

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 5b2c15214a6b..3d03b4c937b9 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -289,7 +289,7 @@ void __init kvmclock_init(void)
 {
 	u8 flags;
 
-	if (!kvm_para_available() || !kvmclock)
+	if (!kvm_para_available() || !kvmclock || cc_platform_has(CC_ATTR_GUEST_SECURE_TSC))
 		return;
 
 	if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
-- 
2.34.1