linux-kernel - [RFC PATCH 09/11] x86/kvmclock: Use Secure TSC as clock if available

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Message-ID: <20230130120327.977460-10-nikunj@amd.com>
Date:   Mon, 30 Jan 2023 17:33:25 +0530
From:   Nikunj A Dadhania <nikunj@....com>
To:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC:     <bp@...en8.de>, <thomas.lendacky@....com>,
        <dionnaglaze@...gle.com>, <pgonda@...gle.com>, <jroedel@...e.de>,
        <mingo@...hat.com>, <tglx@...utronix.de>,
        <dave.hansen@...ux.intel.com>, <seanjc@...gle.com>,
        <pbonzini@...hat.com>, <nikunj@....com>, <michael.roth@....com>,
        <ketanch@...k.ac.in>
Subject: [RFC PATCH 09/11] x86/kvmclock: Use Secure TSC as clock if available

For AMD SNP guests having Secure TSC enabled, use Secure TSC based
clocksource instead of kvmclock.

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 16333ba1904b..a0c207c62307 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 || cc_platform_has(CC_ATTR_GUEST_SECURE_TSC))
 		return;
 
 	if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
-- 
2.32.0