linux-kernel - [PATCH v4 10/11] KVM: nVMX: Enable nested TSC scaling

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Date:   Wed, 26 May 2021 19:44:17 +0100
From:   Ilias Stamatis <ilstam@...zon.com>
To:     <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <pbonzini@...hat.com>
CC:     <mlevitsk@...hat.com>, <seanjc@...gle.com>, <vkuznets@...hat.com>,
        <wanpengli@...cent.com>, <jmattson@...gle.com>, <joro@...tes.org>,
        <zamsden@...il.com>, <mtosatti@...hat.com>, <dwmw@...zon.co.uk>,
        <ilstam@...zon.com>
Subject: [PATCH v4 10/11] KVM: nVMX: Enable nested TSC scaling

Calculate the TSC offset and multiplier on nested transitions and expose
the TSC scaling feature to L1.

Signed-off-by: Ilias Stamatis <ilstam@...zon.com>
Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/vmx/nested.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 239154d3e4e7..e8183e224706 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2277,7 +2277,8 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
 				  SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE |
 				  SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 				  SECONDARY_EXEC_APIC_REGISTER_VIRT |
-				  SECONDARY_EXEC_ENABLE_VMFUNC);
+				  SECONDARY_EXEC_ENABLE_VMFUNC |
+				  SECONDARY_EXEC_TSC_SCALING);
 		if (nested_cpu_has(vmcs12,
 				   CPU_BASED_ACTIVATE_SECONDARY_CONTROLS))
 			exec_control |= vmcs12->secondary_vm_exec_control;
@@ -2532,6 +2533,15 @@ 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 +3363,6 @@ 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 +4470,11 @@ 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);
@@ -6473,7 +6484,8 @@ void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps)
 		SECONDARY_EXEC_RDRAND_EXITING |
 		SECONDARY_EXEC_ENABLE_INVPCID |
 		SECONDARY_EXEC_RDSEED_EXITING |
-		SECONDARY_EXEC_XSAVES;
+		SECONDARY_EXEC_XSAVES |
+		SECONDARY_EXEC_TSC_SCALING;
 
 	/*
 	 * We can emulate "VMCS shadowing," even if the hardware
-- 
2.17.1