KVM: X86: Let kvm-clock report the right tsc frequency

This patch changes the kvm_guest_time_update function to use
TSC frequency the guest actually has for updating its clock.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 15 insertions, 10 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0d6524fa2aff..78d729174d99 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -969,6 +969,14 @@ static inline int kvm_tsc_changes_freq(void)
         return ret;
 }
 
+static u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu)
+{
+        if (vcpu->arch.virtual_tsc_khz)
+                return vcpu->arch.virtual_tsc_khz;
+        else
+                return __this_cpu_read(cpu_tsc_khz);
+}
+
 static inline u64 nsec_to_cycles(u64 nsec)
 {
         u64 ret;
@@ -982,20 +990,19 @@ static inline u64 nsec_to_cycles(u64 nsec)
         return ret;
 }
 
-static void kvm_arch_set_tsc_khz(struct kvm *kvm, u32 this_tsc_khz)
+static void kvm_init_tsc_catchup(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
 {
         /* Compute a scale to convert nanoseconds in TSC cycles */
         kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
-                           &kvm->arch.virtual_tsc_shift,
-                           &kvm->arch.virtual_tsc_mult);
-        kvm->arch.virtual_tsc_khz = this_tsc_khz;
+                           &vcpu->arch.tsc_catchup_shift,
+                           &vcpu->arch.tsc_catchup_mult);
 }
 
 static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns)
 {
         u64 tsc = pvclock_scale_delta(kernel_ns-vcpu->arch.last_tsc_nsec,
-                                      vcpu->kvm->arch.virtual_tsc_mult,
-                                      vcpu->kvm->arch.virtual_tsc_shift);
+                                      vcpu->arch.tsc_catchup_mult,
+                                      vcpu->arch.tsc_catchup_shift);
         tsc += vcpu->arch.last_tsc_write;
         return tsc;
 }
@@ -1062,8 +1069,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
         local_irq_save(flags);
         kvm_get_msr(v, MSR_IA32_TSC, &tsc_timestamp);
         kernel_ns = get_kernel_ns();
-        this_tsc_khz = __this_cpu_read(cpu_tsc_khz);
-
+        this_tsc_khz = vcpu_tsc_khz(v);
         if (unlikely(this_tsc_khz == 0)) {
                 local_irq_restore(flags);
                 kvm_make_request(KVM_REQ_CLOCK_UPDATE, v);
@@ -6060,8 +6066,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
         }
         vcpu->arch.pio_data = page_address(page);
 
-        if (!kvm->arch.virtual_tsc_khz)
-                kvm_arch_set_tsc_khz(kvm, max_tsc_khz);
+        kvm_init_tsc_catchup(vcpu, max_tsc_khz);
 
         r = kvm_mmu_create(vcpu);
         if (r < 0)