linux-kernel - Re: [PATCH v4 3/6] KVM: VMX: Detect Tertiary VM-Execution control when setup VMCS config

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Message-ID: <60d6f343-058a-5fbe-5265-ccb38689bb93@intel.com>
Date:   Sat, 18 Sep 2021 00:15:50 +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 v4 3/6] KVM: VMX: Detect Tertiary VM-Execution control
 when setup VMCS config

On 9/11/2021 5:35 AM, Sean Christopherson wrote:
> On Mon, Aug 09, 2021, Zeng Guang wrote:
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index 927a552393b9..ee8c5664dc95 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -2391,6 +2391,23 @@ static __init int adjust_vmx_controls(u32 ctl_min, u32 ctl_opt,
>>   	return 0;
>>   }
>>   
>> +static __init int adjust_vmx_controls_64(u64 ctl_min, u64 ctl_opt,
>> +					 u32 msr, u64 *result)
>> +{
>> +	u64 vmx_msr;
>> +	u64 ctl = ctl_min | ctl_opt;
>> +
>> +	rdmsrl(msr, vmx_msr);
>> +	ctl &= vmx_msr; /* bit == 1 means it can be set */
>> +
>> +	/* Ensure minimum (required) set of control bits are supported. */
>> +	if (ctl_min & ~ctl)
>> +		return -EIO;
>> +
>> +	*result = ctl;
>> +	return 0;
>> +}
> More succinctly, since we don't need to force-set bits in the final value:
>
> 	u64 allowed1;
>
> 	rdmsrl(msr, allowed1);
>
> 	/* Ensure minimum (required) set of control bits are supported. */
> 	if (ctl_min & ~allowed1)
> 		return -EIO;
>
> 	*result = (ctl_min | ctl_opt) & allowed1;
> 	return 0;
Yes, it becomes more concise. I will change it . Thanks.
>>   static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>>   				    struct vmx_capability *vmx_cap)
>>   {