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

[Zeng Guang <guang.zeng@intel.com>]

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)
>>   {