linux-kernel - Re: [PATCH] KVM: VMX: Set VMENTER_L1D_FLUSH_NOT_REQUIRED if !X86_BUG

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Date:   Fri, 27 Sep 2019 18:04:06 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Borislav Petkov <bp@...en8.de>, Waiman Long <longman@...hat.com>
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: VMX: Set VMENTER_L1D_FLUSH_NOT_REQUIRED if
 !X86_BUG_L1TF

On 27/09/19 17:55, Borislav Petkov wrote:
> I'd move that logic with the if (boot_cpu_has(X86_BUG_L1TF)) check inside
> vmx_setup_l1d_flush() so that I have this:
> 
>         if (!boot_cpu_has_bug(X86_BUG_L1TF)) {
>                 l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NOT_REQUIRED;
>                 return 0;
>         }
> 
> 	if (!enable_ept) {
> 		...
> 
> 	}
> 
> inside the function and outside am left with:
> 
> 	r = vmx_setup_l1d_flush(vmentry_l1d_flush_param);
>         if (r) {
> 		vmx_exit();
>                 return r;
> 	}
> 
> only. This way I'm concentrating the whole l1tf_vmx_mitigation picking
> apart in one place.

Right you are, I'm sending v2.

Paolo