linux-kernel - Re: [PATCH] x86/kvm: Don't waste kvmclock memory if there is nopv parameter

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Message-ID: <6e57aad6-1322-8a3d-6dfa-ff010a61a9a9@redhat.com>
Date:   Tue, 8 Mar 2022 13:13:54 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH] x86/kvm: Don't waste kvmclock memory if there is nopv
 parameter

On 3/8/22 09:18, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
> 
> When the "nopv" command line parameter is used, it should not waste
> memory for kvmclock.
> 
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
>   arch/x86/kernel/kvmclock.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index c5caa73..16333ba 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -239,7 +239,7 @@ static void __init kvmclock_init_mem(void)
>   
>   static int __init kvm_setup_vsyscall_timeinfo(void)
>   {
> -	if (!kvm_para_available() || !kvmclock)
> +	if (!kvm_para_available() || !kvmclock || nopv)
>   		return 0;
>   
>   	kvmclock_init_mem();

Perhaps instead !kvm_para_available() && nopv should clear the kvmclock 
variable?

Paolo