linux-kernel - Re: [PATCH 11/23] KVM: MMU: do not recompute root level from kvm_mmu_role

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Date:   Mon, 7 Feb 2022 22:17:17 +0000
From:   David Matlack <dmatlack@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        seanjc@...gle.com, vkuznets@...hat.com
Subject: Re: [PATCH 11/23] KVM: MMU: do not recompute root level from
 kvm_mmu_role_regs

On Mon, Feb 07, 2022 at 10:10:39PM +0000, David Matlack wrote:
> On Fri, Feb 04, 2022 at 06:57:06AM -0500, Paolo Bonzini wrote:
> > The root_level can be found in the cpu_role (in fact the field
> > is superfluous and could be removed, but one thing at a time).
> > Since there is only one usage left of role_regs_to_root_level,
> > inline it into kvm_calc_cpu_role.
> > 
> > Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> > ---
> >  arch/x86/kvm/mmu/mmu.c | 23 ++++++++---------------
> >  1 file changed, 8 insertions(+), 15 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index f98444e1d834..74789295f922 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -253,19 +253,6 @@ static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu)
> >  	return regs;
> >  }
> >  
> > -static int role_regs_to_root_level(const struct kvm_mmu_role_regs *regs)
> > -{
> > -	if (!____is_cr0_pg(regs))
> > -		return 0;
> > -	else if (____is_efer_lma(regs))
> > -		return ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL :
> > -					       PT64_ROOT_4LEVEL;
> > -	else if (____is_cr4_pae(regs))
> > -		return PT32E_ROOT_LEVEL;
> > -	else
> > -		return PT32_ROOT_LEVEL;
> > -}
> > -
> >  static inline bool kvm_available_flush_tlb_with_range(void)
> >  {
> >  	return kvm_x86_ops.tlb_remote_flush_with_range;
> > @@ -4673,7 +4660,13 @@ kvm_calc_cpu_role(struct kvm_vcpu *vcpu, const struct kvm_mmu_role_regs *regs)
> >  		role.base.smep_andnot_wp = ____is_cr4_smep(regs) && !____is_cr0_wp(regs);
> >  		role.base.smap_andnot_wp = ____is_cr4_smap(regs) && !____is_cr0_wp(regs);
> >  		role.base.has_4_byte_gpte = !____is_cr4_pae(regs);
> > -		role.base.level = role_regs_to_root_level(regs);
> > +
> > +		if (____is_efer_lma(regs))
> > +			role.base.level = ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL : PT64_ROOT_4LEVEL;
> > +		else if (____is_cr4_pae(regs))
> > +			role.base.level = PT32E_ROOT_LEVEL;
> > +		else
> > +			role.base.level = PT32_ROOT_LEVEL;
> 
> Did you mean to drop the !CR0.PG case?

Oh never mind I see the !CR0.PG case is handled above.

Reviewed-by: David Matlack <dmatlack@...gle.com>

> 
> >  
> >  		role.ext.cr0_pg = 1;
> >  		role.ext.cr4_pae = ____is_cr4_pae(regs);
> > @@ -4766,7 +4759,7 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu,
> >  	context->get_guest_pgd = get_cr3;
> >  	context->get_pdptr = kvm_pdptr_read;
> >  	context->inject_page_fault = kvm_inject_page_fault;
> > -	context->root_level = role_regs_to_root_level(regs);
> > +	context->root_level = cpu_role.base.level;
> >  
> >  	if (!is_cr0_pg(context))
> >  		context->gva_to_gpa = nonpaging_gva_to_gpa;
> > -- 
> > 2.31.1
> > 
> >