linux-kernel - Re: [PATCH 02/22] kvm: mmu: Introduce tdp

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Message-ID: <61d23bc0-771d-9110-6528-3658a55ccba6@redhat.com>
Date:   Wed, 30 Sep 2020 08:24:17 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Ben Gardon <bgardon@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Cannon Matthews <cannonmatthews@...gle.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 02/22] kvm: mmu: Introduce tdp_iter

On 30/09/20 07:24, Sean Christopherson wrote:
> Maybe use the params, if only to avoid the line wrap?
> 
> 	iter->gfn = goal_gfn - (goal_gfn % KVM_PAGES_PER_HPAGE(root_level));
> 
> Actually, peeking further into the file, this calculation is repeated in both
> try_step_up and try_step_down,  probably worth adding a helper of some form.

Also it's written more concisely as

	iter->gfn = goal_gfn & -KVM_PAGES_PER_HPAGE(iter->level);

> 
> 
> 	bool done;
> 
> 	if (try_step_down(iter))
> 		return;
> 
> 	do {
> 		done = try_step_side(iter);
> 	} while (!done && try_step_up(iter));
> 
> 	iter->valid = done;

I pointed out something similar in my review, my version was

	bool done;

	if (try_step_down(iter))
		return;

	do {
		if (try_step_side(iter))
			return;
	} while (try_step_up(iter));
	iter->valid = false;

Paolo