linux-kernel - Re: [PATCH 2/2] KVM: VMX: Don't expose PLE enable if there is no hardware support

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Date:   Wed, 27 Sep 2017 13:54:08 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Wanpeng Li <kernellwp@...il.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH 2/2] KVM: VMX: Don't expose PLE enable if there is no
 hardware support

On Tue, Sep 26, 2017 at 11:34:22PM -0700, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@...mail.com>
> 
> PLE_Window: Software can configure this field as an upper bound on the amount of time
> a guest is allowed to execute in a PAUSE LOOP.
> 
> KVM doesn't expose the PLE capability to the L1 hypervsior, however, ple_window still

s/hypervsior/hypervisor/
> shows the default value on L1 hypervsior. This patch fixes it by clearing all the

Ditto here.
> PLE related module parameter if there is no PLE capability.
> 
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

> ---
>  arch/x86/kvm/vmx.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index c83d28b..4d4f9b4 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6781,8 +6781,13 @@ static __init int hardware_setup(void)
>  	if (enable_ept && !cpu_has_vmx_ept_2m_page())
>  		kvm_disable_largepages();
>  
> -	if (!cpu_has_vmx_ple())
> +	if (!cpu_has_vmx_ple()) {
>  		ple_gap = 0;
> +		ple_window = 0;
> +		ple_window_grow = 0;
> +		ple_window_max = 0;
> +		ple_window_shrink = 0;
> +	}
>  
>  	if (!cpu_has_vmx_apicv()) {
>  		enable_apicv = 0;
> -- 
> 2.7.4
>