linux-kernel - Re: [RFC 09/14] KVM: x86/MMU: Only make pages available on Shadow MMU fault

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Date:   Thu, 29 Dec 2022 10:30:20 -0800
From:   David Matlack <dmatlack@...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>,
        Sean Christopherson <seanjc@...gle.com>,
        Vipin Sharma <vipinsh@...gle.com>,
        Nagareddy Reddy <nspreddy@...gle.com>
Subject: Re: [RFC 09/14] KVM: x86/MMU: Only make pages available on Shadow MMU fault

On Wed, Dec 21, 2022 at 2:24 PM Ben Gardon <bgardon@...gle.com> wrote:
>
> Now that the Shadow MMU has been factored out of mmu.c and the naming
> sheme has been cleaned up, it's clear that there's an unnecessary
> operation in direct_page_fault(). Since the MMU page quota is only
> applied to the Shadow MMU, there's no point to calling
> kvm_shadow_mmu_make_pages_available on a fault where the TDP MMU is
> going to handle installing new TDP PTEs.

Jinx! An equivalent change recently went into kvm/queue:

https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?h=queue&id=1290f90e77186bf8a06a3a35ebf254f5b004676b