Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH 07/22] kvm: mmu: Support zapping SPTEs in the TDP MMU
To:     Ben Gardon <bgardon@google.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     Cannon Matthews <cannonmatthews@google.com>,
        Peter Xu <peterx@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Peter Shier <pshier@google.com>,
        Peter Feiner <pfeiner@google.com>,
        Junaid Shahid <junaids@google.com>,
        Jim Mattson <jmattson@google.com>,
        Yulei Zhang <yulei.kernel@gmail.com>,
        Wanpeng Li <kernellwp@gmail.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Xiao Guangrong <xiaoguangrong.eric@gmail.com>
References: <20200925212302.3979661-1-bgardon@google.com>
 <20200925212302.3979661-8-bgardon@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <4fd0ef13-77bd-ed84-684a-be364a62f8fa@redhat.com>
Date:   Sat, 26 Sep 2020 02:14:58 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.11.0
MIME-Version: 1.0
In-Reply-To: <20200925212302.3979661-8-bgardon@google.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

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;
> +	}