linux-kernel - Re: [PATCH 3/6] KVM: VMX: Detect Tertiary VM-Execution control when setup VMCS config

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Message-ID: <05faffb4-c22d-1cd5-7582-823de9dd109a@intel.com>
Date:   Mon, 2 Aug 2021 14:59:47 +0800
From:   Zeng Guang <guang.zeng@...el.com>
To:     Sean Christopherson <seanjc@...gle.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" <kvm@...r.kernel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Luck, Tony" <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>,
        "Huang, Kai" <kai.huang@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Hu, Robert" <robert.hu@...el.com>,
        "Gao, Chao" <chao.gao@...el.com>,
        Robert Hoo <robert.hu@...ux.intel.com>
Subject: Re: [PATCH 3/6] KVM: VMX: Detect Tertiary VM-Execution control when
 setup VMCS config

On 7/29/2021 8:03 AM, Sean Christopherson wrote:
> On Fri, Jul 16, 2021, Zeng Guang wrote:
>> @@ -4204,6 +4234,13 @@ vmx_adjust_secondary_exec_control(struct vcpu_vmx *vmx, u32 *exec_control,
>>   #define vmx_adjust_sec_exec_exiting(vmx, exec_control, lname, uname) \
>>   	vmx_adjust_sec_exec_control(vmx, exec_control, lname, uname, uname##_EXITING, true)
>>   
>> +static void vmx_compute_tertiary_exec_control(struct vcpu_vmx *vmx)
>> +{
>> +	u32 exec_control = vmcs_config.cpu_based_3rd_exec_ctrl;
> This is incorrectly truncating the value.
>
>> +
>> +	vmx->tertiary_exec_control = exec_control;
>> +}
>> +
>>   static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
>>   {
>>   	struct kvm_vcpu *vcpu = &vmx->vcpu;
>> @@ -4319,6 +4356,11 @@ static void init_vmcs(struct vcpu_vmx *vmx)
>>   		secondary_exec_controls_set(vmx, vmx->secondary_exec_control);
>>   	}
>>   
>> +	if (cpu_has_tertiary_exec_ctrls()) {
>> +		vmx_compute_tertiary_exec_control(vmx);
>> +		tertiary_exec_controls_set(vmx, vmx->tertiary_exec_control);
> IMO, the existing vmx->secondary_exec_control is an abomination that should not
> exist.  Looking at the code, it's actually not hard to get rid, there's just one
> annoying use in prepare_vmcs02_early() that requires a bit of extra work to get
> rid of.
>
> Anyways, for tertiary controls, I'd prefer to avoid the same mess and instead
> follow vmx_exec_control(), both in functionality and in name:
>
>    static u64 vmx_tertiary_exec_control(struct vcpu_vmx *vmx)
>    {
> 	return vmcs_config.cpu_based_3rd_exec_ctrl;
>    }
>
> and:
>
> 	if (cpu_has_tertiary_exec_ctrls())
> 		tertiary_exec_controls_set(vmx, vmx_tertiary_exec_control(vmx));
>
> and then the next patch becomes:
>
>    static u64 vmx_tertiary_exec_control(struct vcpu_vmx *vmx)
>    {
> 	u64 exec_control = vmcs_config.cpu_based_3rd_exec_ctrl;
>
> 	if (!kvm_vcpu_apicv_active(vcpu))
> 		exec_control &= ~TERTIARY_EXEC_IPI_VIRT;
>
> 	return exec_control;
>    }
>
>
> And I'll work on a patch to purge vmx->secondary_exec_control.
Ok, it looks much concise. I will change as you suggest. Thanks.
>> +	}
>> +
>>   	if (kvm_vcpu_apicv_active(&vmx->vcpu)) {
>>   		vmcs_write64(EOI_EXIT_BITMAP0, 0);
>>   		vmcs_write64(EOI_EXIT_BITMAP1, 0);
>> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
>> index 945c6639ce24..c356ceebe84c 100644
>> --- a/arch/x86/kvm/vmx/vmx.h
>> +++ b/arch/x86/kvm/vmx/vmx.h
>> @@ -266,6 +266,7 @@ struct vcpu_vmx {
>>   	u32		      msr_ia32_umwait_control;
>>   
>>   	u32 secondary_exec_control;
>> +	u64 tertiary_exec_control;
>>   
>>   	/*
>>   	 * loaded_vmcs points to the VMCS currently used in this vcpu. For a
>> -- 
>> 2.25.1
>>