KVM: Fix last_guest_tsc / tsc_offset semantics

[platform/adaptation/renesas_rcar/renesas_kernel.git] / arch / x86 / kvm / x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 030d495..2a59f76 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1079,6 +1079,7 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
        vcpu->arch.hv_clock.tsc_timestamp = 0;
        vcpu->arch.last_tsc_write = data;
        vcpu->arch.last_tsc_nsec = ns;
+       vcpu->arch.last_guest_tsc = data;
 }
 EXPORT_SYMBOL_GPL(kvm_write_tsc);
 
@@ -1147,7 +1148,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
         * observed by the guest and ensure the new system time is greater.
         */
        max_kernel_ns = 0;
-       if (vcpu->hv_clock.tsc_timestamp && vcpu->last_guest_tsc) {
+       if (vcpu->hv_clock.tsc_timestamp) {
                max_kernel_ns = vcpu->last_guest_tsc -
                                vcpu->hv_clock.tsc_timestamp;
                max_kernel_ns = pvclock_scale_delta(max_kernel_ns,
@@ -2257,13 +2258,14 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
                u64 tsc;
 
                tsc = kvm_x86_ops->read_l1_tsc(vcpu);
-               tsc_delta = !vcpu->arch.last_guest_tsc ? 0 :
-                            tsc - vcpu->arch.last_guest_tsc;
+               tsc_delta = tsc - vcpu->arch.last_guest_tsc;
 
                if (tsc_delta < 0)
                        mark_tsc_unstable("KVM discovered backwards TSC");
                if (check_tsc_unstable()) {
-                       kvm_x86_ops->adjust_tsc_offset(vcpu, -tsc_delta);
+                       u64 offset = kvm_x86_ops->compute_tsc_offset(vcpu,
+                                               vcpu->arch.last_guest_tsc);
+                       kvm_x86_ops->write_tsc_offset(vcpu, offset);
                        vcpu->arch.tsc_catchup = 1;
                }
                kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);