linux-kernel - [PATCH v6 13/16] x86/kvmclock: Skip kvmclock when Secure TSC is available

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Message-ID: <20231128125959.1810039-14-nikunj@amd.com>
Date:   Tue, 28 Nov 2023 18:29:56 +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 v6 13/16] 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>
---
 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 fb8f52149be9..e3de354abf74 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -288,7 +288,7 @@ void __init kvmclock_init(void)
 {
 	u8 flags;
 
-	if (!kvm_para_available() || !kvmclock)
+	if (!kvm_para_available() || !kvmclock || cpu_feature_enabled(X86_FEATURE_SNP_SECURE_TSC))
 		return;
 
 	if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
-- 
2.34.1