linux-kernel - Re: [PATCH] kvm: correct comment description issue

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Message-ID: <Yg/DmdjSqNLwWo2d@google.com>
Date:   Fri, 18 Feb 2022 16:04:41 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Peng Hao <flyingpenghao@...il.com>
Cc:     pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH]  kvm: correct comment description issue

"KVM: VMX:" for the scope.  A more specific shortlog would also be helfpul, stating
that a comment is being modified doesn't provide any info about what comment.

On Fri, Feb 18, 2022, Peng Hao wrote:
> loaded_vmcs does not have this field 'vcpu', modify this comment.

It would be helpful to state that loaded_vmcs has 'cpu', not 'vcpu'.  It's hard to
identify what's being changed.


Something like this?

  KVM: VMX: Fix typos above smp_wmb() comment in __loaded_vmcs_clear()

  Fix a comment documenting the memory barrier related to clearing a
  loaded_vmcs; loaded_vmcs tracks the host CPU the VMCS is loaded on via
  the field 'cpu', it doesn't have a 'vcpu' field.

With a tweaked shortlog/changelog (doesn't have to be exactly the above),

Reviewed-by: Sean Christopherson <seanjc@...gle.com>

> Signed-off-by: Peng Hao <flyingpeng@...cent.com>
> ---
>  arch/x86/kvm/vmx/vmx.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 7dce746c175f..0ffcfe54eea5 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -644,10 +644,10 @@ static void __loaded_vmcs_clear(void *arg)
>  
>  	/*
>  	 * Ensure all writes to loaded_vmcs, including deleting it from its
> -	 * current percpu list, complete before setting loaded_vmcs->vcpu to
> -	 * -1, otherwise a different cpu can see vcpu == -1 first and add
> -	 * loaded_vmcs to its percpu list before it's deleted from this cpu's
> -	 * list. Pairs with the smp_rmb() in vmx_vcpu_load_vmcs().
> +	 * current percpu list, complete before setting loaded_vmcs->cpu to
> +	 * -1, otherwise a different cpu can see loaded_vmcs->cpu == -1 first
> +	 * and add loaded_vmcs to its percpu list before it's deleted from this
> +	 * cpu's list. Pairs with the smp_rmb() in vmx_vcpu_load_vmcs().
>  	 */
>  	smp_wmb();
>  
> -- 
> 2.27.0
>