linux-kernel - Re: [PATCH v2 2/9] x86/kvm/mmu.c: set get_pdptr hook in kvm_init_shadow_ept

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Date:   Wed, 26 Sep 2018 07:11:29 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Liran Alon <liran.alon@...cle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/9] x86/kvm/mmu.c: set get_pdptr hook in
 kvm_init_shadow_ept_mmu()

On Tue, Sep 25, 2018 at 07:58:37PM +0200, Vitaly Kuznetsov wrote:
> kvm_init_shadow_ept_mmu() doesn't set get_pdptr() hook and is this
> not a problem just because MMU context is already initialized and this
> hook points to kvm_pdptr_read(). As we're intended to use a dedicated
> MMU for shadow EPT MMU set this hook explicitly.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/mmu.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index ca79ec0d8060..2bdc63f67886 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -4846,6 +4846,8 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
>  	context->root_level = PT64_ROOT_4LEVEL;
>  	context->direct_map = false;
>  	context->base_role.word = root_page_role.word & mmu_base_role_mask.word;
> +	context->get_pdptr = kvm_pdptr_read;

Would it make sense to set this in nested_ept_init_mmu_context()
along with set_cr3, get_cr3 and inject_page_fault?  The other MMU
flows set them as a package deal.

Either way...

Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>

> +
>  	update_permission_bitmask(vcpu, context, true);
>  	update_pkru_bitmask(vcpu, context, true);
>  	update_last_nonleaf_level(vcpu, context);