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/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 3cce71413d0be86278a7037eccc692d3d205b4e8..485b4f1f079b130346c584d78e5a5edbd47d3267 100644 (file)
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -118,6 +118,7 @@
    complete list. */
 
 #define MSR_AMD64_PATCH_LEVEL          0x0000008b
+#define MSR_AMD64_TSC_RATIO            0xc0000104
 #define MSR_AMD64_NB_CFG               0xc001001f
 #define MSR_AMD64_PATCH_LOADER         0xc0010020
 #define MSR_AMD64_OSVW_ID_LENGTH       0xc0010140

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 779b09194f03efd22ba1274815c24114c075b200..830150099958d5913c720190ddeafd7780741ffa 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -63,6 +63,8 @@ MODULE_LICENSE("GPL");
 
 #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 @@ struct vcpu_svm {
        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 int has_svm(void)
 
 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 @@ static int svm_hardware_enable(void *garbage)
 
        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 @@ 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)
+{
+       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 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
                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 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
        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 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 *data)
        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: