linux-kernel - Re: [PATCH 5/7] KVM: mmu: remove argument to kvm_init_shadow_mmu and kvm_init_shadow_ept

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Date:	Thu, 3 Oct 2013 14:25:55 +0300
From:	Gleb Natapov <gleb@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH 5/7] KVM: mmu: remove argument to kvm_init_shadow_mmu and
 kvm_init_shadow_ept_mmu

On Wed, Oct 02, 2013 at 04:56:14PM +0200, Paolo Bonzini wrote:
> The initialization function in mmu.c can always use walk_mmu, which
> is known to be vcpu->arch.mmu.  Only init_kvm_nested_mmu is used to
> initialize vcpu->arch.nested_mmu.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  arch/x86/kvm/mmu.c | 15 +++++++++------
>  arch/x86/kvm/mmu.h |  5 ++---
>  arch/x86/kvm/svm.c |  4 ++--
>  arch/x86/kvm/vmx.c |  4 ++--
>  4 files changed, 15 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 40772ef..ac598c8 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -3742,11 +3742,13 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
>  	update_last_pte_bitmap(vcpu, context);
>  }
>  
> -void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
> +void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu)
>  {
>  	bool smep = kvm_read_cr4_bits(vcpu, X86_CR4_SMEP);
> +	struct kvm_mmu *context = vcpu->arch.walk_mmu;
I'd rather use &vcpu->arch.mmu here.

> +
>  	ASSERT(vcpu);
> -	ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
> +	ASSERT(!VALID_PAGE(context->root_hpa));
>  
>  	if (!is_paging(vcpu))
>  		nonpaging_init_context(vcpu, context);
> @@ -3765,11 +3767,12 @@ void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
>  }
>  EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
>  
> -void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context,
> -		bool execonly)
> +void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly)
>  {
> +	struct kvm_mmu *context = vcpu->arch.walk_mmu;
> +
>  	ASSERT(vcpu);
> -	ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
> +	ASSERT(!VALID_PAGE(context->root_hpa));
>  
>  	context->shadow_root_level = kvm_x86_ops->get_tdp_level();
>  
> @@ -3790,7 +3793,7 @@ EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu);
>  
>  static void init_kvm_softmmu(struct kvm_vcpu *vcpu)
>  {
> -	kvm_init_shadow_mmu(vcpu, vcpu->arch.walk_mmu);
> +	kvm_init_shadow_mmu(vcpu);
>  	vcpu->arch.walk_mmu->set_cr3           = kvm_x86_ops->set_cr3;
>  	vcpu->arch.walk_mmu->get_cr3           = get_cr3;
>  	vcpu->arch.walk_mmu->get_pdptr         = kvm_pdptr_read;
And change walk_mmu to mmu here too for consistency with all other
places. Basically if you want to initialize use mmu or nested_mmu.
Use walk_mmu pointer only when you need to use mmu.

> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 2926152..c9d3d8f 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -70,9 +70,8 @@ enum {
>  };
>  
>  int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct);
> -void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
> -void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context,
> -		bool execonly);
> +void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu);
> +void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly);
>  
>  static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
>  {
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index c7168a5..37bcd6b 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1961,8 +1961,8 @@ static void nested_svm_inject_npf_exit(struct kvm_vcpu *vcpu,
>  
>  static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
>  {
> -	kvm_init_shadow_mmu(vcpu, &vcpu->arch.mmu);
> -
> +	WARN_ON(mmu_is_nested(vcpu));
> +	kvm_init_shadow_mmu(vcpu);
>  	vcpu->arch.mmu.set_cr3           = nested_svm_set_tdp_cr3;
>  	vcpu->arch.mmu.get_cr3           = nested_svm_get_tdp_cr3;
>  	vcpu->arch.mmu.get_pdptr         = nested_svm_get_tdp_pdptr;
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 2db9164..fdd1cb8 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7501,9 +7501,9 @@ static unsigned long nested_ept_get_cr3(struct kvm_vcpu *vcpu)
>  
>  static void nested_ept_init_mmu_context(struct kvm_vcpu *vcpu)
>  {
> -	kvm_init_shadow_ept_mmu(vcpu, &vcpu->arch.mmu,
> +	WARN_ON(mmu_is_nested(vcpu));
> +	kvm_init_shadow_ept_mmu(vcpu,
>  			nested_vmx_ept_caps & VMX_EPT_EXECUTE_ONLY_BIT);
> -
>  	vcpu->arch.mmu.set_cr3           = vmx_set_cr3;
>  	vcpu->arch.mmu.get_cr3           = nested_ept_get_cr3;
>  	vcpu->arch.mmu.inject_page_fault = nested_ept_inject_page_fault;
> -- 
> 1.8.3.1
> 

--
			Gleb.
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