linux-kernel - [tip: x86/vmware] x86/vmware: Avoid TSC recalibration when frequency is known

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Date:   Sun, 28 Mar 2021 19:14:54 -0000
From:   "tip-bot2 for Alexey Makhalov" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Alexey Makhalov <amakhalov@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/vmware] x86/vmware: Avoid TSC recalibration when frequency is known

The following commit has been merged into the x86/vmware branch of tip:

Commit-ID:     0b4a285e2c65c2c9449c6eccb87298e385213e7b
Gitweb:        https://git.kernel.org/tip/0b4a285e2c65c2c9449c6eccb87298e385213e7b
Author:        Alexey Makhalov <amakhalov@...are.com>
AuthorDate:    Mon, 04 Jan 2021 16:47:52 -08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Sun, 28 Mar 2021 21:11:43 +02:00

x86/vmware: Avoid TSC recalibration when frequency is known

When the TSC frequency is known because it is retrieved from the
hypervisor, skip TSC refined calibration by setting X86_FEATURE_TSC_KNOWN_FREQ.

Signed-off-by: Alexey Makhalov <amakhalov@...are.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20210105004752.131069-1-amakhalov@vmware.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 c6ede3b..8316411 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)