linux-kernel - [PATCH v2 01/12] KVM: x86: Collect information for setting TSC scaling ratio

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Date:	Tue, 20 Oct 2015 15:39:01 +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@...mail.com>,
	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	mdontu@...defender.com, Kai Huang <kai.huang@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	linux-kernel@...r.kernel.org,
	Haozhong Zhang <haozhong.zhang@...el.com>
Subject: [PATCH v2 01/12] KVM: x86: Collect information for setting TSC scaling ratio

The number of bits of the fractional part of the 64-bit TSC scaling
ratio in VMX and SVM is different. This patch makes the architecture
code to collect the number of fractional bits and other related
information into variables that can be accessed in the common code.

Signed-off-by: Haozhong Zhang <haozhong.zhang@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 6 ++++++
 arch/x86/kvm/svm.c              | 4 ++++
 arch/x86/kvm/x86.c              | 6 ++++++
 3 files changed, 16 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 53deb27..0540dc8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -990,6 +990,12 @@ extern bool kvm_has_tsc_control;
 extern u32  kvm_min_guest_tsc_khz;
 /* maximum supported tsc_khz for guests */
 extern u32  kvm_max_guest_tsc_khz;
+/* number of bits of the fractional part of the TSC scaling ratio */
+extern u8   kvm_tsc_scaling_ratio_frac_bits;
+/* default TSC scaling ratio (= 1.0) */
+extern u64  kvm_default_tsc_scaling_ratio;
+/* maximum allowed value of TSC scaling ratio */
+extern u64  kvm_max_tsc_scaling_ratio;
 
 enum emulation_result {
 	EMULATE_DONE,         /* no further processing */
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index cd8659c..55f5f49 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -908,7 +908,11 @@ static __init int svm_hardware_setup(void)
 		max = min(0x7fffffffULL, __scale_tsc(tsc_khz, TSC_RATIO_MAX));
 
 		kvm_max_guest_tsc_khz = max;
+
+		kvm_max_tsc_scaling_ratio = TSC_RATIO_MAX;
+		kvm_tsc_scaling_ratio_frac_bits = 32;
 	}
+	kvm_default_tsc_scaling_ratio = TSC_RATIO_DEFAULT;
 
 	if (nested) {
 		printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9e9c226..79cbbb5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -109,6 +109,12 @@ bool kvm_has_tsc_control;
 EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
 u32  kvm_max_guest_tsc_khz;
 EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+u8   kvm_tsc_scaling_ratio_frac_bits;
+EXPORT_SYMBOL_GPL(kvm_tsc_scaling_ratio_frac_bits);
+u64  kvm_default_tsc_scaling_ratio;
+EXPORT_SYMBOL_GPL(kvm_default_tsc_scaling_ratio);
+u64  kvm_max_tsc_scaling_ratio;
+EXPORT_SYMBOL_GPL(kvm_max_tsc_scaling_ratio);
 
 /* tsc tolerance in parts per million - default to 1/2 of the NTP threshold */
 static u32 tsc_tolerance_ppm = 250;
-- 
2.4.8

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