[Devel] [PATCH 02/16] KVM: x86: Collect information for setting TSC scaling ratio

[Roman Kagan]

From: Haozhong Zhang <haozhong.zhang at intel.com>

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 at intel.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(cherry-picked from commit bc9b961b357ea8129d75613b7af4fdf57ced9b9f)
Signed-off-by: Denis Plotnikov <dplotnikov at virtuozzo.com>
Signed-off-by: Roman Kagan <rkagan at virtuozzo.com>
---
 arch/x86/include/asm/kvm_host.h | 4 ++++
 arch/x86/kvm/svm.c              | 3 +++
 arch/x86/kvm/x86.c              | 4 ++++
 3 files changed, 11 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 51ad191..e4cff52 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -947,6 +947,10 @@ u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu);
 extern bool kvm_has_tsc_control;
 /* 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;
+/* 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 12850b2..71b7c57 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -904,6 +904,9 @@ 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;
 	}
 
 	if (nested) {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 992f20c..e911037 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -108,6 +108,10 @@ bool __read_mostly kvm_has_tsc_control;
 EXPORT_SYMBOL_GPL(kvm_has_tsc_control);
 u32  __read_mostly kvm_max_guest_tsc_khz;
 EXPORT_SYMBOL_GPL(kvm_max_guest_tsc_khz);
+u8   __read_mostly kvm_tsc_scaling_ratio_frac_bits;
+EXPORT_SYMBOL_GPL(kvm_tsc_scaling_ratio_frac_bits);
+u64  __read_mostly 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 __read_mostly tsc_tolerance_ppm = 250;
-- 
2.7.4