linux-kernel - Re: [PATCH v3 10/18] x86/virt: KVM: Move VMXOFF helpers into KVM VMX

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Message-ID: <79073b9c22cf60ac87896f0bbcdfd905196e1b4a.camel@intel.com>
Date:   Mon, 22 May 2023 13:15:47 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Gao, Chao" <chao.gao@...el.com>,
        "andrew.cooper3@...rix.com" <andrew.cooper3@...rix.com>
Subject: Re: [PATCH v3 10/18] x86/virt: KVM: Move VMXOFF helpers into KVM VMX

On Fri, 2023-05-12 at 16:50 -0700, Sean Christopherson wrote:
> Now that VMX is disabled in emergencies via the virt callbacks, move the
> VMXOFF helpers into KVM, the only remaining user.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Kai Huang <kai.huang@...el.com>

One nit ...

[...]


>  static void vmx_emergency_disable(void)
>  {
>  	int cpu = raw_smp_processor_id();
> @@ -753,7 +775,8 @@ static void vmx_emergency_disable(void)
>  			    loaded_vmcss_on_cpu_link)
>  		vmcs_clear(v->vmcs);
>  
> -	__cpu_emergency_vmxoff();
> +	if (__read_cr4() & X86_CR4_VMXE)
> +		kvm_cpu_vmxoff();
>  }

As replied to patch 3, is it better to move CR4.VMXE bit check before VMCLEAR
(can be done in either patch 3, or here)?