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From: Paolo Bonzini <pbonzini@redhat.com>
To: ilstam@mailbox.org, kvm@vger.kernel.org
Cc: ilstam@amazon.com, seanjc@google.com, vkuznets@redhat.com,
	wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org,
	haozhong.zhang@intel.com, zamsden@gmail.com, mtosatti@redhat.com,
	dplotnikov@virtuozzo.com, dwmw@amazon.co.uk
Subject: Re: [PATCH 4/8] KVM: VMX: Adjust the TSC-related VMCS fields on L2 entry and exit
Date: Thu, 6 May 2021 13:32:57 +0200	[thread overview]
Message-ID: <50f86951-1cea-b7aa-7236-f28edd5eca8d@redhat.com> (raw)
In-Reply-To: <20210506103228.67864-5-ilstam@mailbox.org>

On 06/05/21 12:32, ilstam@mailbox.org wrote:
> +	if (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING) {
> +		if (vmcs12->secondary_vm_exec_control & SECONDARY_EXEC_TSC_SCALING) {
> +			vcpu->arch.tsc_offset = kvm_compute_02_tsc_offset(
> +					vcpu->arch.l1_tsc_offset,
> +					vmcs12->tsc_multiplier,
> +					vmcs12->tsc_offset);
> +
> +			vcpu->arch.tsc_scaling_ratio = mul_u64_u64_shr(
> +					vcpu->arch.tsc_scaling_ratio,
> +					vmcs12->tsc_multiplier,
> +					kvm_tsc_scaling_ratio_frac_bits);
> +		} else {
> +			vcpu->arch.tsc_offset += vmcs12->tsc_offset;
> +		}

The computation of vcpu->arch.tsc_offset is (not coincidentially) the
same that appears in patch 6

+	    (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING)) {
+		if (vmcs12->secondary_vm_exec_control & SECONDARY_EXEC_TSC_SCALING) {
+			cur_offset = kvm_compute_02_tsc_offset(
+					l1_offset,
+					vmcs12->tsc_multiplier,
+					vmcs12->tsc_offset);
+		} else {
+			cur_offset = l1_offset + vmcs12->tsc_offset;

So I think you should just pass vmcs12 and the L1 offset to
kvm_compute_02_tsc_offset, and let it handle both cases (and possibly
even set vcpu->arch.tsc_scaling_ratio in the same function).

Paolo


  reply	other threads:[~2021-05-06 11:33 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-06 10:32 [PATCH 0/8] KVM: VMX: Implement nested TSC scaling ilstam
2021-05-06 10:32 ` [PATCH 1/8] KVM: VMX: Add a TSC multiplier field in VMCS12 ilstam
2021-05-06 14:50   ` kernel test robot
2021-05-06 17:36   ` Jim Mattson
2021-05-10 13:42   ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 2/8] KVM: X86: Store L1's TSC scaling ratio in 'struct kvm_vcpu_arch' ilstam
2021-05-10 13:43   ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 3/8] KVM: X86: Pass an additional 'L1' argument to kvm_scale_tsc() ilstam
2021-05-10 13:52   ` Maxim Levitsky
2021-05-10 15:44     ` Stamatis, Ilias
2021-05-06 10:32 ` [PATCH 4/8] KVM: VMX: Adjust the TSC-related VMCS fields on L2 entry and exit ilstam
2021-05-06 11:32   ` Paolo Bonzini [this message]
2021-05-06 17:35     ` Stamatis, Ilias
2021-05-10 14:11       ` Paolo Bonzini
2021-05-10 13:53   ` Maxim Levitsky
2021-05-10 14:44     ` Stamatis, Ilias
2021-05-11 12:38       ` Maxim Levitsky
2021-05-11 15:11         ` Stamatis, Ilias
2021-05-06 10:32 ` [PATCH 5/8] KVM: X86: Move tracing outside write_l1_tsc_offset() ilstam
2021-05-10 13:54   ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 6/8] KVM: VMX: Make vmx_write_l1_tsc_offset() work with nested TSC scaling ilstam
2021-05-10 13:54   ` Maxim Levitsky
2021-05-10 16:08     ` Stamatis, Ilias
2021-05-11 12:44       ` Maxim Levitsky
2021-05-11 17:44         ` Stamatis, Ilias
2021-05-06 10:32 ` [PATCH 7/8] KVM: VMX: Expose TSC scaling to L2 ilstam
2021-05-10 13:56   ` Maxim Levitsky
2021-05-06 10:32 ` [PATCH 8/8] KVM: selftests: x86: Add vmx_nested_tsc_scaling_test ilstam
2021-05-10 13:59   ` Maxim Levitsky
2021-05-11 11:16     ` Stamatis, Ilias
2021-05-11 12:47       ` Maxim Levitsky
2021-05-11 14:02         ` Stamatis, Ilias
2021-05-06 17:16 ` [PATCH 0/8] KVM: VMX: Implement nested TSC scaling Jim Mattson
2021-05-06 17:48   ` Stamatis, Ilias
2021-05-10 13:43     ` Maxim Levitsky
2021-05-10 14:29   ` Paolo Bonzini

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