[PATCH] KVM: x86/mmu: Remove the repeated declaration

[PATCH] KVM: x86/mmu: Remove the repeated declaration

[Shaokun Zhang]

Function 'is_nx_huge_page_enabled' is declared twice, remove the
repeated declaration.

Cc: Ben Gardon <bgardon@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
---
 arch/x86/kvm/mmu/mmu_internal.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index d64ccb417c60..54c6e6193ff2 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -158,8 +158,6 @@ int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,
 void disallowed_hugepage_adjust(u64 spte, gfn_t gfn, int cur_level,
 				kvm_pfn_t *pfnp, int *goal_levelp);
 
-bool is_nx_huge_page_enabled(void);
-
 void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
 
 void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
-- 
2.7.4

Re: [PATCH] KVM: x86/mmu: Remove the repeated declaration

[Sean Christopherson]

On Tue, May 25, 2021, Shaokun Zhang wrote:
> Function 'is_nx_huge_page_enabled' is declared twice, remove the
> repeated declaration.
> 
> Cc: Ben Gardon <bgardon@google.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
> ---
>  arch/x86/kvm/mmu/mmu_internal.h | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
> index d64ccb417c60..54c6e6193ff2 100644
> --- a/arch/x86/kvm/mmu/mmu_internal.h
> +++ b/arch/x86/kvm/mmu/mmu_internal.h
> @@ -158,8 +158,6 @@ int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,
>  void disallowed_hugepage_adjust(u64 spte, gfn_t gfn, int cur_level,
>  				kvm_pfn_t *pfnp, int *goal_levelp);
>  
> -bool is_nx_huge_page_enabled(void);

Rather than simply delete the extra declaration, what about converting this to
static inline and opportunistically deleting the duplicate?  The implementation
is a single operation and this is MMU-internal, i.e. there's no need to export
and limited exposure of nx_huge_pages to other code.

> -
>  void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
>  
>  void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
> -- 
> 2.7.4
> 

Re: [PATCH] KVM: x86/mmu: Remove the repeated declaration

[Shaokun Zhang]

Hi Sean,

On 2021/5/26 0:09, Sean Christopherson wrote:
> On Tue, May 25, 2021, Shaokun Zhang wrote:
>> Function 'is_nx_huge_page_enabled' is declared twice, remove the
>> repeated declaration.
>>
>> Cc: Ben Gardon <bgardon@google.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
>> ---
>>  arch/x86/kvm/mmu/mmu_internal.h | 2 --
>>  1 file changed, 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
>> index d64ccb417c60..54c6e6193ff2 100644
>> --- a/arch/x86/kvm/mmu/mmu_internal.h
>> +++ b/arch/x86/kvm/mmu/mmu_internal.h
>> @@ -158,8 +158,6 @@ int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,
>>  void disallowed_hugepage_adjust(u64 spte, gfn_t gfn, int cur_level,
>>  				kvm_pfn_t *pfnp, int *goal_levelp);
>>  
>> -bool is_nx_huge_page_enabled(void);
> 
> Rather than simply delete the extra declaration, what about converting this to
> static inline and opportunistically deleting the duplicate?  The implementation

It seems that you want to make it static inline in mmu_internal.h, right?

> is a single operation and this is MMU-internal, i.e. there's no need to export
> and limited exposure of nx_huge_pages to other code.

If is_nx_huge_page_enabled is inline in mmu_internal.h, nx_huge_pages will be
external in mmu_internal.h and exposed to other code. Do I miss something?

Thanks,
Shaokun

> 
>> -
>>  void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
>>  
>>  void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp);
>> -- 
>> 2.7.4
>>
> .
> 

Re: [PATCH] KVM: x86/mmu: Remove the repeated declaration

[Sean Christopherson]

On Wed, May 26, 2021, Shaokun Zhang wrote:
> Hi Sean,
> 
> On 2021/5/26 0:09, Sean Christopherson wrote:
> > Rather than simply delete the extra declaration, what about converting this to
> > static inline and opportunistically deleting the duplicate?  The implementation
> 
> It seems that you want to make it static inline in mmu_internal.h, right?

Yep.

> > is a single operation and this is MMU-internal, i.e. there's no need to export
> > and limited exposure of nx_huge_pages to other code.
> 
> If is_nx_huge_page_enabled is inline in mmu_internal.h, nx_huge_pages will be
> external in mmu_internal.h and exposed to other code. Do I miss something?

Yes, it will be theoretically exposed to other code, but as the name suggests,
mmu_internal.h should not be included by anything outside of mmu/, and of course
we can reject patches that try to access nx_guest_pages directly.