[PATCH v3 10/12] KVM: VMX: Set the TSC offset and multiplier on nested entry and exit

Ilias Stamatis
2021-05-21T10:29:04Z

Calculate the nested TSC offset and multiplier on entering L2 using the
corresponding functions. Restore the L1 values on L2's exit.

Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
---
arch/x86/kvm/vmx/nested.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 239154d3e4e7..f75c4174cbcf 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2532,6 +2532,15 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
vmcs_write64(GUEST_IA32_PAT, vmx->vcpu.arch.pat);
}

+ vcpu->arch.tsc_offset = kvm_calc_nested_tsc_offset(
+ vcpu->arch.l1_tsc_offset,
+ vmx_get_l2_tsc_offset(vcpu),
+ vmx_get_l2_tsc_multiplier(vcpu));
+
+ vcpu->arch.tsc_scaling_ratio = kvm_calc_nested_tsc_multiplier(
+ vcpu->arch.l1_tsc_scaling_ratio,
+ vmx_get_l2_tsc_multiplier(vcpu));
+
vmcs_write64(TSC_OFFSET, vcpu->arch.tsc_offset);
if (kvm_has_tsc_control)
vmcs_write64(TSC_MULTIPLIER, vcpu->arch.tsc_scaling_ratio);
@@ -3353,8 +3362,6 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
}

enter_guest_mode(vcpu);
- if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING)
- vcpu->arch.tsc_offset += vmcs12->tsc_offset;

if (prepare_vmcs02(vcpu, vmcs12, &entry_failure_code)) {
exit_reason.basic = EXIT_REASON_INVALID_STATE;
@@ -4462,8 +4469,11 @@ void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason,
if (nested_cpu_has_preemption_timer(vmcs12))
hrtimer_cancel(&to_vmx(vcpu)->nested.preemption_timer);

- if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING)
- vcpu->arch.tsc_offset -= vmcs12->tsc_offset;
+ if (nested_cpu_has(vmcs12, CPU_BASED_USE_TSC_OFFSETTING)) {
+ vcpu->arch.tsc_offset = vcpu->arch.l1_tsc_offset;
+ if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_TSC_SCALING))
+ vcpu->arch.tsc_scaling_ratio = vcpu->arch.l1_tsc_scaling_ratio;
+ }

if (likely(!vmx->fail)) {
sync_vmcs02_to_vmcs12(vcpu, vmcs12);
--
2.17.1