linux-kernel - [PATCH v2] x86/acrn: Set X86_FEATURE_TSC_KNOWN

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Date:   Tue,  1 Nov 2022 13:30:19 +0800
From:   Fei Li <fei1.li@...el.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org, peterz@...radead.org
Cc:     dave.hansen@...el.com, gregkh@...uxfoundation.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, Yu1.Wang@...el.com,
        conghui.chen@...el.com, fengwei.yin@...el.com
Subject: [PATCH v2] x86/acrn: Set X86_FEATURE_TSC_KNOWN_FREQ

If the TSC frequency is known from the acrn_get_tsc_khz(),
the TSC frequency does not need to be recalibrated.

Avoiding recalibration by setting X86_FEATURE_TSC_KNOWN_FREQ.
This patch also removes `inline` for acrn_get_tsc_khz() since
it doesn't make sense.

Signed-off-by: Fei Li <fei1.li@...el.com>
Reviewed-by: Yin, Fengwei <fengwei.yin@...el.com>

---
v2:
- Detail the commit message
---
 arch/x86/include/asm/acrn.h | 5 -----
 arch/x86/kernel/cpu/acrn.c  | 6 ++++++
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/acrn.h b/arch/x86/include/asm/acrn.h
index 1dd14381bcb6..aa12c74ea959 100644
--- a/arch/x86/include/asm/acrn.h
+++ b/arch/x86/include/asm/acrn.h
@@ -30,11 +30,6 @@ static inline u32 acrn_cpuid_base(void)
 	return 0;
 }
 
-static inline unsigned long acrn_get_tsc_khz(void)
-{
-	return cpuid_eax(ACRN_CPUID_TIMING_INFO);
-}
-
 /*
  * Hypercalls for ACRN
  *
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index 485441b7f030..c5ff75b6a949 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -24,6 +24,12 @@ static u32 __init acrn_detect(void)
 	return acrn_cpuid_base();
 }
 
+static unsigned long acrn_get_tsc_khz(void)
+{
+	setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
+	return cpuid_eax(ACRN_CPUID_TIMING_INFO);
+}
+
 static void __init acrn_init_platform(void)
 {
 	/* Setup the IDT for ACRN hypervisor callback */

base-commit: 5aaef24b5c6d4246b2cac1be949869fa36577737
-- 
2.34.1