linux-kernel - Re: [PATCH v9 6/6] KVM: x86/mmu: Handle non-refcounted pages

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Message-ID: <d272613e-aed9-4cbc-26dd-78bc8fca2650@collabora.com>
Date:   Mon, 18 Sep 2023 12:53:22 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     David Stevens <stevensd@...omium.org>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v9 6/6] KVM: x86/mmu: Handle non-refcounted pages

On 9/11/23 05:16, David Stevens wrote:
> --- a/arch/x86/kvm/mmu/paging_tmpl.h
> +++ b/arch/x86/kvm/mmu/paging_tmpl.h
> @@ -848,7 +848,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
>  
>  out_unlock:
>  	write_unlock(&vcpu->kvm->mmu_lock);
> -	kvm_release_pfn_clean(fault->pfn);
> +	if (fault->is_refcounted_page)
> +		kvm_set_page_accessed(pfn_to_page(fault->pfn));

The other similar occurrences in the code that replaced
kvm_release_pfn_clean() with kvm_set_page_accessed() did it under the
held mmu_lock.

Does kvm_set_page_accessed() needs to be invoked under the lock?

-- 
Best regards,
Dmitry