linux-kernel - [PATCH 10/12] KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded

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Date:	Mon, 28 Sep 2015 13:38:09 +0800
From:	Haozhong Zhang <haozhong.zhang@...el.com>
To:	kvm@...r.kernel.org
Cc:	Gleb Natapov <gleb@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Joerg Roedel <joro@...tes.org>,
	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	Mihai Donțu <mdontu@...defender.com>,
	Andy Lutomirski <luto@...nel.org>,
	Kai Huang <kai.huang@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	Haozhong Zhang <haozhong.zhang@...el.com>
Subject: [PATCH 10/12] KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded

This patch makes kvm-intel module to load TSC scaling ratio into TSC
multiplier field of VMCS when a vcpu is loaded, so that TSC scaling
ratio can take effect if VMX TSC scaling is enabled.

Signed-off-by: Haozhong Zhang <haozhong.zhang@...el.com>
---
 arch/x86/kvm/vmx.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ef19eb8..e282eb8 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1952,6 +1952,12 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 		rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
 		vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
+
+		/* Setup TSC multiplier */
+		if (cpu_has_vmx_tsc_scaling())
+			vmcs_write64(TSC_MULTIPLIER,
+				     vcpu->arch.tsc_scaling_ratio);
+
 		vmx->loaded_vmcs->cpu = cpu;
 	}
 }
-- 
2.4.8

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