linux-kernel - Re: [PATCH v4 1/3] KVM: x86: Update trace function for nested VM entry to support VMX

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Date:   Tue, 30 Aug 2022 20:31:20 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Mingwei Zhang <mizhang@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH v4 1/3] KVM: x86: Update trace function for nested VM
 entry to support VMX

On Thu, Aug 25, 2022, Mingwei Zhang wrote:
> Update trace function for nested VM entry to support VMX. Existing trace
> function only supports nested VMX and the information printed out is AMD
> specific.
> 
> So, update trace_kvm_nested_vmrun() to trace_kvm_nested_vmenter(), since
> 'vmenter' is generic. Add a new field 'isa' to recognize Intel and AMD;
> Update the output to print out VMX/SVM related naming respectively, eg.,
> vmcb vs. vmcs; npt vs. ept.
> 
> Opportunistically update the call site of trace_kvm_nested_vmenter() to make
> one line per parameter.
> 
> Signed-off-by: Mingwei Zhang <mizhang@...gle.com>
> ---
>  arch/x86/kvm/svm/nested.c |  6 ++++--
>  arch/x86/kvm/trace.h      | 28 ++++++++++++++++++----------
>  arch/x86/kvm/x86.c        |  2 +-
>  3 files changed, 23 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 76dcc8a3e849..835c508eed8e 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -781,11 +781,13 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa,
>  	struct vcpu_svm *svm = to_svm(vcpu);
>  	int ret;
>  
> -	trace_kvm_nested_vmrun(svm->vmcb->save.rip, vmcb12_gpa,
> +	trace_kvm_nested_vmenter(svm->vmcb->save.rip,
> +			       vmcb12_gpa,
>  			       vmcb12->save.rip,
>  			       vmcb12->control.int_ctl,
>  			       vmcb12->control.event_inj,
> -			       vmcb12->control.nested_ctl);
> +			       vmcb12->control.nested_ctl,
> +			       KVM_ISA_SVM);

Align indentation.

>  
>  	trace_kvm_nested_intercepts(vmcb12->control.intercepts[INTERCEPT_CR] & 0xffff,
>  				    vmcb12->control.intercepts[INTERCEPT_CR] >> 16,
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index 2120d7c060a9..e7f0da9474f0 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -589,10 +589,11 @@ TRACE_EVENT(kvm_pv_eoi,
>  /*
>   * Tracepoint for nested VMRUN
>   */
> -TRACE_EVENT(kvm_nested_vmrun,
> +TRACE_EVENT(kvm_nested_vmenter,
>  	    TP_PROTO(__u64 rip, __u64 vmcb, __u64 nested_rip, __u32 int_ctl,
> -		     __u32 event_inj, bool npt),
> -	    TP_ARGS(rip, vmcb, nested_rip, int_ctl, event_inj, npt),
> +		     __u32 event_inj, bool tdp_enabled, __u32 isa),
> +	    TP_ARGS(rip, vmcb, nested_rip, int_ctl, event_inj, tdp_enabled,
> +		    isa),

Let this poke out, "isa" feels quite lonely here.  It's a moot point when patch 3
comes along, mostly a "for future reference" thing.
 
>  	TP_STRUCT__entry(
>  		__field(	__u64,		rip		)
> @@ -600,7 +601,8 @@ TRACE_EVENT(kvm_nested_vmrun,
>  		__field(	__u64,		nested_rip	)
>  		__field(	__u32,		int_ctl		)
>  		__field(	__u32,		event_inj	)
> -		__field(	bool,		npt		)
> +		__field(	bool,		tdp_enabled	)
> +		__field(	__u32,		isa		)
>  	),
>  
>  	TP_fast_assign(
> @@ -609,14 +611,20 @@ TRACE_EVENT(kvm_nested_vmrun,
>  		__entry->nested_rip	= nested_rip;
>  		__entry->int_ctl	= int_ctl;
>  		__entry->event_inj	= event_inj;
> -		__entry->npt		= npt;
> +		__entry->tdp_enabled	= tdp_enabled;
> +		__entry->isa		= isa;
>  	),
>  
> -	TP_printk("rip: 0x%016llx vmcb: 0x%016llx nrip: 0x%016llx int_ctl: 0x%08x "
> -		  "event_inj: 0x%08x npt: %s",
> -		__entry->rip, __entry->vmcb, __entry->nested_rip,
> -		__entry->int_ctl, __entry->event_inj,
> -		__entry->npt ? "on" : "off")
> +	TP_printk("rip: 0x%016llx %s: 0x%016llx nested_rip: 0x%016llx "
> +		  "int_ctl: 0x%08x event_inj: 0x%08x nested_%s: %s",
> +		__entry->rip,
> +		__entry->isa == KVM_ISA_VMX ? "vmcs" : "vmcb",
> +		__entry->vmcb,
> +		__entry->nested_rip,
> +		__entry->int_ctl,
> +		__entry->event_inj,
> +		__entry->isa == KVM_ISA_VMX ? "ept" : "npt",
> +		__entry->tdp_enabled ? "on" : "off")

Align indentation.