linux-kernel - Re: [Patch v3 2/9] KVM: x86/mmu: Remove zapped_obsolete_pages from struct kvm

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Message-ID: <Y64N05SXYWf8IG+6@google.com>
Date:   Thu, 29 Dec 2022 13:59:47 -0800
From:   David Matlack <dmatlack@...gle.com>
To:     Vipin Sharma <vipinsh@...gle.com>
Cc:     seanjc@...gle.com, pbonzini@...hat.com, bgardon@...gle.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Patch v3 2/9] KVM: x86/mmu: Remove zapped_obsolete_pages from
 struct kvm_arch{}

On Wed, Dec 21, 2022 at 06:34:50PM -0800, Vipin Sharma wrote:
> zapped_obsolete_pages list was used in struct kvm_arch{} to provide
> pages for KVM MMU shrinker. This is not needed now as KVM MMU shrinker
> has been repurposed to free shadow page caches and not
> zapped_obsolete_pages.
> 
> Remove zapped_obsolete_pages from struct kvm_arch{} and use local list
> in kvm_zap_obsolete_pages().
> 
> Signed-off-by: Vipin Sharma <vipinsh@...gle.com>

Reviewed-by: David Matlack <dmatlack@...gle.com>

> ---
>  arch/x86/include/asm/kvm_host.h | 1 -
>  arch/x86/kvm/mmu/mmu.c          | 8 ++++----
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 89cc809e4a00..f89f02e18080 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1215,7 +1215,6 @@ struct kvm_arch {
>  	u8 mmu_valid_gen;
>  	struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES];
>  	struct list_head active_mmu_pages;
> -	struct list_head zapped_obsolete_pages;
>  	/*
>  	 * A list of kvm_mmu_page structs that, if zapped, could possibly be
>  	 * replaced by an NX huge page.  A shadow page is on this list if its
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 157417e1cb6e..3364760a1695 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5987,6 +5987,7 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm)
>  {
>  	struct kvm_mmu_page *sp, *node;
>  	int nr_zapped, batch = 0;
> +	LIST_HEAD(zapped_pages);

optional nit: The common name of this is invalid_list (see other callers
of __kvm_mmu_prepare_zap_page()).