linux-kernel - Re: [PATCH 12/13] KVM: x86/mmu: Fast invalidation for TDP MMU

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Message-ID: <79548215-b86f-99de-9322-c76ba5a1802d@redhat.com>
Date:   Thu, 1 Apr 2021 12:36:15 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>
Subject: Re: [PATCH 12/13] KVM: x86/mmu: Fast invalidation for TDP MMU

On 31/03/21 23:08, Ben Gardon wrote:
>   
> +	if (is_tdp_mmu_enabled(kvm))
> +		kvm_tdp_mmu_invalidate_roots(kvm);
> +
>   	/*
>   	 * Toggle mmu_valid_gen between '0' and '1'.  Because slots_lock is
>   	 * held for the entire duration of zapping obsolete pages, it's
> @@ -5451,9 +5454,6 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm)
>   
>   	kvm_zap_obsolete_pages(kvm);
>   
> -	if (is_tdp_mmu_enabled(kvm))
> -		kvm_tdp_mmu_zap_all(kvm);
> -

This is just cosmetic, but I'd prefer to keep the call to 
kvm_tdp_mmu_invalidate_roots at the original place, so that it's clear 
in the next patch that it's two separate parts because of the different 
locking requirements.

Paolo