Re: [PATCH 5/8] KVM: X86: Move tracing outside write_l1_tsc_offset()

From: Maxim Levitsky <mlevitsk@redhat.com>
To: ilstam@mailbox.org, kvm@vger.kernel.org, pbonzini@redhat.com
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 5/8] KVM: X86: Move tracing outside write_l1_tsc_offset()
Date: Mon, 10 May 2021 16:54:03 +0300	[thread overview]
Message-ID: <e2fcb43ba6ef92675fa0565065164909f5a4909e.camel@redhat.com> (raw)
In-Reply-To: <20210506103228.67864-6-ilstam@mailbox.org>

On Thu, 2021-05-06 at 10:32 +0000, ilstam@mailbox.org wrote:
> From: Ilias Stamatis <ilstam@amazon.com>
> 
> A subsequent patch fixes write_l1_tsc_offset() to account for nested TSC
> scaling. Calculating the L1 TSC for logging it with the trace call
> becomes more complex then.
> 
> This patch moves the trace call to the caller and avoids code
> duplication as a result too.
> 
> Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
> ---
>  arch/x86/kvm/svm/svm.c | 4 ----
>  arch/x86/kvm/vmx/vmx.c | 3 ---
>  arch/x86/kvm/x86.c     | 4 ++++
>  3 files changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 9790c73f2a32..d2f9d6a9716f 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1090,10 +1090,6 @@ static u64 svm_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
>  		svm->vmcb01.ptr->control.tsc_offset = offset;
>  	}
>  
> -	trace_kvm_write_tsc_offset(vcpu->vcpu_id,
> -				   svm->vmcb->control.tsc_offset - g_tsc_offset,
> -				   offset);
> -
>  	svm->vmcb->control.tsc_offset = offset + g_tsc_offset;
>  
>  	vmcb_mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index cbe0cdade38a..49241423b854 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1812,9 +1812,6 @@ static u64 vmx_write_l1_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
>  	    (vmcs12->cpu_based_vm_exec_control & CPU_BASED_USE_TSC_OFFSETTING))
>  		g_tsc_offset = vmcs12->tsc_offset;
>  
> -	trace_kvm_write_tsc_offset(vcpu->vcpu_id,
> -				   vcpu->arch.tsc_offset - g_tsc_offset,
> -				   offset);
>  	vmcs_write64(TSC_OFFSET, offset + g_tsc_offset);
>  	return offset + g_tsc_offset;
>  }
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 87deb119c521..c08295bcf50e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2299,6 +2299,10 @@ EXPORT_SYMBOL_GPL(kvm_read_l1_tsc);
>  
>  static void kvm_vcpu_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
>  {
> +	trace_kvm_write_tsc_offset(vcpu->vcpu_id,
> +				   vcpu->arch.l1_tsc_offset,
> +				   offset);
> +
>  	vcpu->arch.l1_tsc_offset = offset;
>  	vcpu->arch.tsc_offset = static_call(kvm_x86_write_l1_tsc_offset)(vcpu, offset);
>  }

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky