linux-kernel - [Patch v4 01/13] x86/hyperv: Add HV_EXPOSE_INVARIANT

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Date:   Mon, 12 Dec 2022 10:37:08 -0800
From:   Vipin Sharma <vipinsh@...gle.com>
To:     seanjc@...gle.com, pbonzini@...hat.com, vkuznets@...hat.com,
        dmatlack@...gle.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michael Kelley <mikelley@...rosoft.com>
Subject: [Patch v4 01/13] x86/hyperv: Add HV_EXPOSE_INVARIANT_TSC define

From: Vitaly Kuznetsov <vkuznets@...hat.com>

Avoid open coding BIT(0) of HV_X64_MSR_TSC_INVARIANT_CONTROL by adding
a dedicated define. While there's only one user at this moment, the
upcoming KVM implementation of Hyper-V Invariant TSC feature will need
to use it as well.

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
Reviewed-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/include/asm/hyperv-tlfs.h | 3 +++
 arch/x86/kernel/cpu/mshyperv.c     | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index e3efaf6e6b62..617332dd64ac 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -255,6 +255,9 @@ enum hv_isolation_type {
 /* TSC invariant control */
 #define HV_X64_MSR_TSC_INVARIANT_CONTROL	0x40000118
 
+/* HV_X64_MSR_TSC_INVARIANT_CONTROL bits */
+#define HV_EXPOSE_INVARIANT_TSC		BIT_ULL(0)
+
 /* Register name aliases for temporary compatibility */
 #define HV_X64_MSR_STIMER0_COUNT	HV_REGISTER_STIMER0_COUNT
 #define HV_X64_MSR_STIMER0_CONFIG	HV_REGISTER_STIMER0_CONFIG
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 831613959a92..e402923800d7 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -388,7 +388,7 @@ static void __init ms_hyperv_init_platform(void)
 		 * setting of this MSR bit should happen before init_intel()
 		 * is called.
 		 */
-		wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x1);
+		wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, HV_EXPOSE_INVARIANT_TSC);
 		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 	}
 
-- 
2.39.0.rc1.256.g54fd8350bd-goog