i/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: x86: Add a common TSC scaling function

Browse Source 
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@intel.com>
[Inline the multiplication and shift steps into mul_u64_u64_shr.  Remove
 BUG_ON.  - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Haozhong Zhang
2015-10-20 15:39:03 +08:00
committed by Paolo Bonzini
parent ad721883e9
commit 35181e86df
5 changed files with 97 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/x86/kvm/svm.c
+4 -44
View File
@@ -212,7 +212,6 @@ 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,
@@ -892,21 +891,7 @@ 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;
}
@@ -972,31 +957,6 @@ 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;
@@ -1065,7 +1025,7 @@ 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;
@@ -1083,7 +1043,7 @@ static u64 svm_compute_tsc_offset(struct kvm_vcpu *vcpu, u64 target_tsc)
{
u64 tsc;
tsc = svm_scale_tsc(vcpu, rdtsc());
tsc = kvm_scale_tsc(vcpu, rdtsc());
return target_tsc - tsc;
}
@@ -3075,7 +3035,7 @@ 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)
@@ -3085,7 +3045,7 @@ 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, rdtsc());
kvm_scale_tsc(vcpu, rdtsc());
break;
}