linux-kernel - Re: [PATCH v2 2/2] KVM: VMX: Don't expose unrestricted

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Date:   Tue, 10 Oct 2017 10:36:48 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v2 2/2] KVM: VMX: Don't expose unrestricted_guest is
 enabled if ept is disabled

On 09/10/2017 13:00, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@...mail.com>
> 
> SDM mentioned: 
> 
>  "If either the “unrestricted guest” VM-execution control or the “mode-based 
>   execute control for EPT” VM- execution control is 1, the “enable EPT” 
>   VM-execution control must also be 1."
> 
> However, we can still observe unrestricted_guest is Y after inserting the kvm-intel.ko 
> w/ ept=N. It depends on later starts a guest in order that the function 
> vmx_compute_secondary_exec_control() can be executed, then both the module parameter 
> and exec control fields will be amended.
> 
> This patch fixes it by amending module parameter immediately during vmcs data setup.
> 
> Reviewed-by: Jim Mattson <jmattson@...gle.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Cc: Jim Mattson <jmattson@...gle.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
> ---
> v1 -> v2: 
>  * reduce to just "enable_ept = 0"
> 
>  arch/x86/kvm/vmx.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ab0f16e..dedff59 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6730,16 +6730,13 @@ static __init int hardware_setup(void)
>  	if (!cpu_has_vmx_ept() ||
>  	    !cpu_has_vmx_ept_4levels() ||
>  	    !cpu_has_vmx_ept_mt_wb() ||
> -	    !cpu_has_vmx_invept_global()) {
> +	    !cpu_has_vmx_invept_global())
>  		enable_ept = 0;
> -		enable_unrestricted_guest = 0;
> -		enable_ept_ad_bits = 0;
> -	}
>  
>  	if (!cpu_has_vmx_ept_ad_bits() || !enable_ept)
>  		enable_ept_ad_bits = 0;
>  
> -	if (!cpu_has_vmx_unrestricted_guest())
> +	if (!cpu_has_vmx_unrestricted_guest() || !enable_ept)
>  		enable_unrestricted_guest = 0;
>  
>  	if (!cpu_has_vmx_flexpriority())
> 

Queued both, thanks.

Paolo