[Devel] [PATCH 04/16] KVM: x86: Add a common TSC scaling function
Roman Kagan
rkagan at virtuozzo.com
Fri Nov 11 00:47:39 PST 2016
From: Haozhong Zhang <haozhong.zhang at intel.com>
VMX and SVM calculate the TSC scaling ratio in a similar logic, so this
patch generalizes it to a common TSC scaling function.
Signed-off-by: Haozhong Zhang <haozhong.zhang at intel.com>
[Inline the multiplication and shift steps into mul_u64_u64_shr. Remove
BUG_ON. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(cherry-picked from commit 35181e86df97e4223f4a28fb33e2bcf3b73de141)
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 | 2 ++
arch/x86/kvm/svm.c | 48 ++++-------------------------------------
arch/x86/kvm/x86.c | 40 +++++++++++++++++++++++++++++++++-
3 files changed, 45 insertions(+), 45 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 44ff862..4e35f42 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1201,6 +1201,8 @@ void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
void kvm_define_shared_msr(unsigned index, u32 msr);
int kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
+u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc);
+
unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu);
bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c613f6e..1efd912 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -211,7 +211,6 @@ static int nested_svm_intercept(struct vcpu_svm *svm);
static int nested_svm_vmexit(struct vcpu_svm *svm);
static int nested_svm_check_exception(struct vcpu_svm *svm, unsigned nr,
bool has_error_code, u32 error_code);
-static u64 __scale_tsc(u64 ratio, u64 tsc);
enum {
VMCB_INTERCEPTS, /* Intercept vectors, TSC offset,
@@ -891,21 +890,7 @@ static __init int svm_hardware_setup(void)
kvm_enable_efer_bits(EFER_FFXSR);
if (boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
- u64 max;
-
kvm_has_tsc_control = true;
-
- /*
- * Make sure the user can only configure tsc_khz values that
- * fit into a signed integer.
- * A min value is not calculated needed because it will always
- * be 1 on all machines and a value of 0 is used to disable
- * tsc-scaling for the vcpu.
- */
- 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;
}
@@ -971,31 +956,6 @@ static void init_sys_seg(struct vmcb_seg *seg, uint32_t type)
seg->base = 0;
}
-static u64 __scale_tsc(u64 ratio, u64 tsc)
-{
- u64 mult, frac, _tsc;
-
- mult = ratio >> 32;
- frac = ratio & ((1ULL << 32) - 1);
-
- _tsc = tsc;
- _tsc *= mult;
- _tsc += (tsc >> 32) * frac;
- _tsc += ((tsc & ((1ULL << 32) - 1)) * frac) >> 32;
-
- return _tsc;
-}
-
-static u64 svm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc)
-{
- u64 _tsc = tsc;
-
- if (vcpu->arch.tsc_scaling_ratio != TSC_RATIO_DEFAULT)
- _tsc = __scale_tsc(vcpu->arch.tsc_scaling_ratio, tsc);
-
- return _tsc;
-}
-
static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale)
{
u64 ratio;
@@ -1064,7 +1024,7 @@ static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment, bool ho
if (host) {
if (vcpu->arch.tsc_scaling_ratio != TSC_RATIO_DEFAULT)
WARN_ON(adjustment < 0);
- adjustment = svm_scale_tsc(vcpu, (u64)adjustment);
+ adjustment = kvm_scale_tsc(vcpu, (u64)adjustment);
}
svm->vmcb->control.tsc_offset += adjustment;
@@ -1082,7 +1042,7 @@ static u64 svm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
{
u64 tsc;
- tsc = svm_scale_tsc(vcpu, native_read_tsc());
+ tsc = kvm_scale_tsc(vcpu, native_read_tsc());
return target_tsc - tsc;
}
@@ -3062,7 +3022,7 @@ static u64 svm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc)
{
struct vmcb *vmcb = get_host_vmcb(to_svm(vcpu));
return vmcb->control.tsc_offset +
- svm_scale_tsc(vcpu, host_tsc);
+ kvm_scale_tsc(vcpu, host_tsc);
}
static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
@@ -3072,7 +3032,7 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
switch (msr_info->index) {
case MSR_IA32_TSC: {
msr_info->data = svm->vmcb->control.tsc_offset +
- svm_scale_tsc(vcpu, native_read_tsc());
+ kvm_scale_tsc(vcpu, native_read_tsc());
break;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e348b4f..4e81751 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1307,6 +1307,33 @@ static void update_ia32_tsc_adjust_msr(struct kvm_vcpu *vcpu, s64 offset)
vcpu->arch.ia32_tsc_adjust_msr += offset - curr_offset;
}
+/*
+ * Multiply tsc by a fixed point number represented by ratio.
+ *
+ * The most significant 64-N bits (mult) of ratio represent the
+ * integral part of the fixed point number; the remaining N bits
+ * (frac) represent the fractional part, ie. ratio represents a fixed
+ * point number (mult + frac * 2^(-N)).
+ *
+ * N equals to kvm_tsc_scaling_ratio_frac_bits.
+ */
+static inline u64 __scale_tsc(u64 ratio, u64 tsc)
+{
+ return mul_u64_u64_shr(tsc, ratio, kvm_tsc_scaling_ratio_frac_bits);
+}
+
+u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc)
+{
+ u64 _tsc = tsc;
+ u64 ratio = vcpu->arch.tsc_scaling_ratio;
+
+ if (ratio != kvm_default_tsc_scaling_ratio)
+ _tsc = __scale_tsc(ratio, tsc);
+
+ return _tsc;
+}
+EXPORT_SYMBOL_GPL(kvm_scale_tsc);
+
void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
{
struct kvm *kvm = vcpu->kvm;
@@ -7476,8 +7503,19 @@ int kvm_arch_hardware_setup(void)
if (r != 0)
return r;
- if (kvm_has_tsc_control)
+ if (kvm_has_tsc_control) {
+ /*
+ * Make sure the user can only configure tsc_khz values that
+ * fit into a signed integer.
+ * A min value is not calculated needed because it will always
+ * be 1 on all machines.
+ */
+ u64 max = min(0x7fffffffULL,
+ __scale_tsc(kvm_max_tsc_scaling_ratio, tsc_khz));
+ kvm_max_guest_tsc_khz = max;
+
kvm_default_tsc_scaling_ratio = 1ULL << kvm_tsc_scaling_ratio_frac_bits;
+ }
kvm_init_msr_list();
return 0;
--
2.7.4
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