linux-kernel - Re: [PATCH 07/22] kvm: mmu: Support zapping SPTEs in the TDP MMU

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Message-ID: <4fd0ef13-77bd-ed84-684a-be364a62f8fa@redhat.com>
Date:   Sat, 26 Sep 2020 02:14:58 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.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 07/22] kvm: mmu: Support zapping SPTEs in the TDP MMU

On 25/09/20 23:22, Ben Gardon wrote:
> +/*
> + * If the MMU lock is contended or this thread needs to yield, flushes
> + * the TLBs, releases, the MMU lock, yields, reacquires the MMU lock,
> + * restarts the tdp_iter's walk from the root, and returns true.
> + * If no yield is needed, returns false.
> + */

The comment is not really necessary. :)

Paolo

> +static bool tdp_mmu_iter_cond_resched(struct kvm *kvm, struct tdp_iter *iter)
> +{
> +	if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
> +		kvm_flush_remote_tlbs(kvm);
> +		cond_resched_lock(&kvm->mmu_lock);
> +		tdp_iter_refresh_walk(iter);
> +		return true;
> +	} else {
> +		return false;
> +	}