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Subject[tip: x86/cleanups] x86/tsc: Do feature check as the very first thing
The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID: 6b8d5dde5b6903baf82fc7400e0b3376b10805b4
Gitweb: https://git.kernel.org/tip/6b8d5dde5b6903baf82fc7400e0b3376b10805b4
Author: Borislav Petkov (AMD) <bp@alien8.de>
AuthorDate: Sun, 18 Dec 2022 21:53:36 +01:00
Committer: Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Sat, 11 Feb 2023 10:44:07 +01:00

x86/tsc: Do feature check as the very first thing

Do the feature check as the very first thing in the function. Everything
else comes after that and is meaningless work if the TSC CPUID bit is
not even set. Switch to cpu_feature_enabled() too, while at it.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/Y5990CUCuWd5jfBH@zn.tnic
---
arch/x86/kernel/tsc.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index eaeffef..aff1d79 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1509,6 +1509,11 @@ void __init tsc_early_init(void)

void __init tsc_init(void)
{
+ if (!cpu_feature_enabled(X86_FEATURE_TSC)) {
+ setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
+ return;
+ }
+
/*
* native_calibrate_cpu_early can only calibrate using methods that are
* available early in boot.
@@ -1516,11 +1521,6 @@ void __init tsc_init(void)
if (x86_platform.calibrate_cpu == native_calibrate_cpu_early)
x86_platform.calibrate_cpu = native_calibrate_cpu;

- if (!boot_cpu_has(X86_FEATURE_TSC)) {
- setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
- return;
- }
-
if (!tsc_khz) {
/* We failed to determine frequencies earlier, try again */
if (!determine_cpu_tsc_frequencies(false)) {
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