Commit 8f6055cb authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity

KVM: X86: Make tsc_delta calculation a function of guest tsc

The calculation of the tsc_delta value to ensure a
forward-going tsc for the guest is a function of the
host-tsc. This works as long as the guests tsc_khz is equal
to the hosts tsc_khz. With tsc-scaling hardware support this
is not longer true and the tsc_delta needs to be calculated
using guest_tsc values.
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 1e993611
...@@ -2113,8 +2113,13 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) ...@@ -2113,8 +2113,13 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
kvm_x86_ops->vcpu_load(vcpu, cpu); kvm_x86_ops->vcpu_load(vcpu, cpu);
if (unlikely(vcpu->cpu != cpu) || check_tsc_unstable()) { if (unlikely(vcpu->cpu != cpu) || check_tsc_unstable()) {
/* Make sure TSC doesn't go backwards */ /* Make sure TSC doesn't go backwards */
s64 tsc_delta = !vcpu->arch.last_host_tsc ? 0 : s64 tsc_delta;
native_read_tsc() - vcpu->arch.last_host_tsc; u64 tsc;
kvm_get_msr(vcpu, MSR_IA32_TSC, &tsc);
tsc_delta = !vcpu->arch.last_guest_tsc ? 0 :
tsc - vcpu->arch.last_guest_tsc;
if (tsc_delta < 0) if (tsc_delta < 0)
mark_tsc_unstable("KVM discovered backwards TSC"); mark_tsc_unstable("KVM discovered backwards TSC");
if (check_tsc_unstable()) { if (check_tsc_unstable()) {
......
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