linux-kernel - Re: [PATCH 06/23] KVM: MMU: load new PGD once nested two-dimensional paging is initialized

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Message-ID: <180d7f0f-8c58-2a52-02a7-bd014d81d7a3@redhat.com>
Date:   Mon, 7 Feb 2022 14:50:57 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     David Matlack <dmatlack@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        seanjc@...gle.com, vkuznets@...hat.com
Subject: Re: [PATCH 06/23] KVM: MMU: load new PGD once nested two-dimensional
 paging is initialized

On 2/4/22 20:18, David Matlack wrote:
> On Fri, Feb 04, 2022 at 06:57:01AM -0500, Paolo Bonzini wrote:
>> __kvm_mmu_new_pgd looks at the MMU's root_level and shadow_root_level
>> via fast_pgd_switch.
> Those checks are just for performance correct (to skip iterating through
> the list of roots)?
> 
> Either way, it's probably worth including a Fixes tag below.
> 

There's no bug because __kvm_mmu_new_pgd is passed a correct new_role. 
But it's unnecessarily complex as shown by patches 7 and 9.

Paolo