linux-kernel - [PATCH] x86/vmware: avoid TSC recalibration

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Date:   Mon, 4 Jan 2021 16:47:52 -0800
From:   Alexey Makhalov <amakhalov@...are.com>
To:     <linux-kernel@...r.kernel.org>,
        <virtualization@...ts.linux-foundation.org>, <hpa@...or.com>,
        <bp@...en8.de>, <mingo@...hat.com>, <tglx@...utronix.de>,
        <pv-drivers@...are.com>, <sdeep@...are.com>
CC:     Alexey Makhalov <amakhalov@...are.com>
Subject: [PATCH] x86/vmware: avoid TSC recalibration

When TSC frequency is known (retrieved from hypervisor), we should skip
TSC refined calibration by setting X86_FEATURE_TSC_KNOWN_FREQ.

Signed-off-by: Alexey Makhalov <amakhalov@...are.com>
---
 arch/x86/kernel/cpu/vmware.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index c6ede3b3d302..83164110ccc5 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -378,6 +378,8 @@ static void __init vmware_set_capabilities(void)
 {
 	setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
 	setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+	if (vmware_tsc_khz)
+		setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
 	if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMCALL)
 		setup_force_cpu_cap(X86_FEATURE_VMCALL);
 	else if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMMCALL)
-- 
2.11.0