linux-kernel - Re: [PATCH 10/12] KVM: MMU: load new PGD after the shadow MMU is initialized

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Message-ID: <Ygagy355RARlppQ4@google.com>
Date:   Fri, 11 Feb 2022 17:45:47 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        vkuznets@...hat.com, mlevitsk@...hat.com, dmatlack@...gle.com
Subject: Re: [PATCH 10/12] KVM: MMU: load new PGD after the shadow MMU is
 initialized

On Wed, Feb 09, 2022, Paolo Bonzini wrote:
> Now that __kvm_mmu_new_pgd does not look at the MMU's root_level and
> shadow_root_level anymore, pull the PGD load after the initialization of
> the shadow MMUs.
> 
> Besides being more intuitive, this enables future simplifications
> and optimizations because it's not necessary anymore to compute the
> role outside kvm_init_mmu.  In particular, kvm_mmu_reset_context was not
> attempting to use a cached PGD to avoid having to figure out the new role.
> It will soon be able to follow what nested_{vmx,svm}_load_cr3 are doing,
> and avoid unloading all the cached roots.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---

If you add a sanity check as described in the other thread[*],

Reviewed-by: Sean Christopherson <seanjc@...gle.com>


[*] https://lore.kernel.org/all/1e8c38eb-d66a-60e7-9432-eb70e7ec1dd4@redhat.com