linux-kernel - Re: [PATCH v5 4/8] KVM: VMX: dump_vmcs() reports tertiary_exec

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Date:   Thu, 13 Jan 2022 21:03:45 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Zeng Guang <guang.zeng@...el.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Tony Luck <tony.luck@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kim Phillips <kim.phillips@....com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jethro Beekman <jethro@...tanix.com>,
        Kai Huang <kai.huang@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Robert Hu <robert.hu@...el.com>,
        Gao Chao <chao.gao@...el.com>,
        Robert Hoo <robert.hu@...ux.intel.com>
Subject: Re: [PATCH v5 4/8] KVM: VMX: dump_vmcs() reports
 tertiary_exec_control field as well

On Fri, Dec 31, 2021, Zeng Guang wrote:
> From: Robert Hoo <robert.hu@...ux.intel.com>
> 
> Add tertiary_exec_control field report in dump_vmcs()
> 
> Signed-off-by: Robert Hoo <robert.hu@...ux.intel.com>
> Signed-off-by: Zeng Guang <guang.zeng@...el.com>
> ---
>  arch/x86/kvm/vmx/vmx.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index fb0f600368c6..5716db9704c0 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -5729,6 +5729,7 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
>  	u32 vmentry_ctl, vmexit_ctl;
>  	u32 cpu_based_exec_ctrl, pin_based_exec_ctrl, secondary_exec_control;
> +	u64 tertiary_exec_control = 0;
>  	unsigned long cr4;
>  	int efer_slot;
>  
> @@ -5746,6 +5747,9 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
>  	if (cpu_has_secondary_exec_ctrls())
>  		secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);

Gah, this (not your) code is silly.  I had to go look at the full source to see
that secondary_exec_control isn't accessed uninitialized...

Can you opportunistically tweak it to the below, and use the same patter for the
tertiary controls?

	if (cpu_has_secondary_exec_ctrls())
		secondary_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
	else
		secondary_exec_control = 0;

>  
> +	if (cpu_has_tertiary_exec_ctrls())
> +		tertiary_exec_control = vmcs_read64(TERTIARY_VM_EXEC_CONTROL);
> +
>  	pr_err("VMCS %p, last attempted VM-entry on CPU %d\n",
>  	       vmx->loaded_vmcs->vmcs, vcpu->arch.last_vmentry_cpu);
>  	pr_err("*** Guest State ***\n");
> @@ -5844,8 +5848,9 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
>  		vmx_dump_msrs("host autoload", &vmx->msr_autoload.host);
>  
>  	pr_err("*** Control State ***\n");
> -	pr_err("PinBased=%08x CPUBased=%08x SecondaryExec=%08x\n",
> -	       pin_based_exec_ctrl, cpu_based_exec_ctrl, secondary_exec_control);
> +	pr_err("PinBased=0x%08x CPUBased=0x%08x SecondaryExec=0x%08x TertiaryExec=0x%016llx\n",
> +	       pin_based_exec_ctrl, cpu_based_exec_ctrl, secondary_exec_control,
> +	       tertiary_exec_control);

Can you provide a sample dump?  It's hard to visualize the output, e.g. I'm worried
this will be overly log and harder to read than putting tertiary controls on their
own line.

>  	pr_err("EntryControls=%08x ExitControls=%08x\n", vmentry_ctl, vmexit_ctl);
>  	pr_err("ExceptionBitmap=%08x PFECmask=%08x PFECmatch=%08x\n",
>  	       vmcs_read32(EXCEPTION_BITMAP),
> -- 
> 2.27.0
>