linux-kernel - Re: [PATCH v13 04/21] KVM: pfncache: add a mark-dirty helper

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Date: Mon, 19 Feb 2024 13:42:06 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paul Durrant <paul@....org>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, David Hildenbrand <david@...hat.com>, 
	Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>, 
	Alexander Gordeev <agordeev@...ux.ibm.com>, Sven Schnelle <svens@...ux.ibm.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, David Woodhouse <dwmw2@...radead.org>, Shuah Khan <shuah@...nel.org>, 
	kvm@...r.kernel.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-s390@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v13 04/21] KVM: pfncache: add a mark-dirty helper

On Thu, Feb 15, 2024, Paul Durrant wrote:
> +/**
> + * kvm_gpc_mark_dirty_in_slot - mark a cached guest page as dirty.
> + *
> + * @gpc:	   struct gfn_to_pfn_cache object.

Meh, just omit the kerneldoc comment.  

> + */
> +static inline void kvm_gpc_mark_dirty_in_slot(struct gfn_to_pfn_cache *gpc)
> +{
> +	lockdep_assert_held(&gpc->lock);
> +	if (gpc->memslot)
> +		mark_page_dirty_in_slot(gpc->kvm, gpc->memslot,
> +					gpc->gpa >> PAGE_SHIFT);

It's kinda silly, but I think it's worth landing this below gpa_to_gfn() so that
there's no need to open code the shift.

And I have a (very) slight preference for an early return.

static inline void kvm_gpc_mark_dirty_in_slot(struct gfn_to_pfn_cache *gpc)
{
	lockdep_assert_held(&gpc->lock);

	if (!gpc->memslot)
		return;

	mark_page_dirty_in_slot(gpc->kvm, gpc->memslot, gpa_to_gfn(gpc->gpa));
}

> +}
> +
>  void kvm_sigset_activate(struct kvm_vcpu *vcpu);
>  void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);
>  
> -- 
> 2.39.2
>