linux-kernel - Re: [PATCH v2 13/28] KVM: x86/mmu: Ensure forward progress when yielding in TDP MMU iter

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Message-ID: <YB3X753GYXQMXYfY@google.com>
Date:   Fri, 5 Feb 2021 15:42:39 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Ben Gardon <bgardon@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.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 v2 13/28] KVM: x86/mmu: Ensure forward progress when
 yielding in TDP MMU iter

On Tue, Feb 02, 2021, Ben Gardon wrote:
> @@ -505,8 +516,8 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
>  
>  		tdp_mmu_set_spte(kvm, &iter, 0);
>  
> -		flush_needed = !can_yield ||
> -			       !tdp_mmu_iter_cond_resched(kvm, &iter, true);
> +		flush_needed = !(can_yield &&
> +				 tdp_mmu_iter_cond_resched(kvm, &iter, true));

Unnecessary change to convert perfectly readable code into an abomination :-D

No need to "fix", it goes aways in the next patch anyways, I just wanted to
complain.

>  	}
>  	return flush_needed;
>  }
> -- 
> 2.30.0.365.g02bc693789-goog
>