linux-kernel - Re: [PATCH 5/9] KVM: selftests: Prevent PAGE

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Message-ID: <aLIPs7eqA_i75Bgy@google.com>
Date: Fri, 29 Aug 2025 13:38:11 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Aqib Faruqui <aqibaf@...zon.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, kvm@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org, 
	nh-open-source@...zon.com
Subject: Re: [PATCH 5/9] KVM: selftests: Prevent PAGE_SIZE redefinition on x86

On Fri, Aug 29, 2025, Aqib Faruqui wrote:
> Prevent PAGE_SIZE redefinition warnings that can occur due to namespace
> pollution from included headers.
> 
> Add an #ifndef directive before defining PAGE_SIZE to avoid redefinition
> conflicts.

Please provide more details on what is causing the conflicts.  Blindly using a
PAGE_SIZE without _knowing_ it's aligned with PAGE_SHIFT and PHYSICAL_PAGE_MASK
is far from ideal.

> Signed-off-by: Aqib Faruqui <aqibaf@...zon.com>
> ---
>  tools/testing/selftests/kvm/include/x86/processor.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
> index 2efb05c2f..3f93d1b4f 100644
> --- a/tools/testing/selftests/kvm/include/x86/processor.h
> +++ b/tools/testing/selftests/kvm/include/x86/processor.h
> @@ -368,7 +368,9 @@ static inline unsigned int x86_model(unsigned int eax)
>  #define PHYSICAL_PAGE_MASK      GENMASK_ULL(51, 12)
>  
>  #define PAGE_SHIFT		12
> +#ifndef PAGE_SIZE
>  #define PAGE_SIZE		(1ULL << PAGE_SHIFT)
> +#endif
>  #define PAGE_MASK		(~(PAGE_SIZE-1) & PHYSICAL_PAGE_MASK)
>  
>  #define HUGEPAGE_SHIFT(x)	(PAGE_SHIFT + (((x) - 1) * 9))
> -- 
> 2.47.3
>