KVM: SVM: Implement infrastructure for TSC_RATE_MSR
This patch enhances the kvm_amd module with functions to
support the TSC_RATE_MSR which can be used to set a given
tsc frequency for the guest vcpu.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 779b091..8301500 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -63,6 +63,8 @@
#define DEBUGCTL_RESERVED_BITS (~(0x3fULL))
+#define TSC_RATIO_RSVD 0xffffff0000000000ULL
+
static bool erratum_383_found __read_mostly;
static const u32 host_save_user_msrs[] = {
@@ -136,8 +138,13 @@
unsigned int3_injected;
unsigned long int3_rip;
u32 apf_reason;
+
+ u64 tsc_ratio;
};
+static DEFINE_PER_CPU(u64, current_tsc_ratio);
+#define TSC_RATIO_DEFAULT 0x0100000000ULL
+
#define MSR_INVALID 0xffffffffU
static struct svm_direct_access_msrs {
@@ -560,6 +567,10 @@
static void svm_hardware_disable(void *garbage)
{
+ /* Make sure we clean up behind us */
+ if (static_cpu_has(X86_FEATURE_TSCRATEMSR))
+ wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT);
+
cpu_svm_disable();
}
@@ -601,6 +612,11 @@
wrmsrl(MSR_VM_HSAVE_PA, page_to_pfn(sd->save_area) << PAGE_SHIFT);
+ if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+ wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT);
+ __get_cpu_var(current_tsc_ratio) = TSC_RATIO_DEFAULT;
+ }
+
svm_init_erratum_383();
return 0;
@@ -843,6 +859,32 @@
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)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+ u64 _tsc = tsc;
+
+ if (svm->tsc_ratio != TSC_RATIO_DEFAULT)
+ _tsc = __scale_tsc(svm->tsc_ratio, tsc);
+
+ return _tsc;
+}
+
static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
{
struct vcpu_svm *svm = to_svm(vcpu);
@@ -1037,6 +1079,8 @@
goto out;
}
+ svm->tsc_ratio = TSC_RATIO_DEFAULT;
+
err = kvm_vcpu_init(&svm->vcpu, kvm, id);
if (err)
goto free_svm;
@@ -1130,6 +1174,12 @@
for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++)
rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
+
+ if (static_cpu_has(X86_FEATURE_TSCRATEMSR) &&
+ svm->tsc_ratio != __get_cpu_var(current_tsc_ratio)) {
+ __get_cpu_var(current_tsc_ratio) = svm->tsc_ratio;
+ wrmsrl(MSR_AMD64_TSC_RATIO, svm->tsc_ratio);
+ }
}
static void svm_vcpu_put(struct kvm_vcpu *vcpu)
@@ -2784,7 +2834,9 @@
case MSR_IA32_TSC: {
struct vmcb *vmcb = get_host_vmcb(svm);
- *data = vmcb->control.tsc_offset + native_read_tsc();
+ *data = vmcb->control.tsc_offset +
+ svm_scale_tsc(vcpu, native_read_tsc());
+
break;
}
case MSR_STAR: