linux-kernel - Re: [PATCH v6 2/3] KVM: vmx: Emulate MSR IA32_UMWAIT

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Message-ID: <fcae19b2-e37e-1a39-1569-f514631913b1@intel.com>
Date:   Fri, 12 Jul 2019 08:42:44 +0800
From:   Tao Xu <tao3.xu@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     rkrcmar@...hat.com, corbet@....net, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        sean.j.christopherson@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, fenghua.yu@...el.com,
        xiaoyao.li@...ux.intel.com, jingqi.liu@...el.com
Subject: Re: [PATCH v6 2/3] KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL

On 7/11/2019 9:25 PM, Paolo Bonzini wrote:
> On 21/06/19 07:57, Tao Xu wrote:
>> +	if (guest_cpuid_has(vcpu, X86_FEATURE_WAITPKG))
>> +		atomic_switch_umwait_control_msr(vmx);
>> +
> 
> guest_cpuid_has is slow.  Please replace it with a test on
> secondary_exec_controls_get(vmx).

Thank you paolo, I will improve it.

> 
> Are you going to look into nested virtualization support?  This should
> include only 1) allowing setting the enable bit in secondary execution
> controls, and passing it through in prepare_vmcs02_early; 2) reflecting
> the vmexit in nested_vmx_exit_reflected.
> 

I will add nested support in next version.

> Thanks,
> 
> Paolo
>