linux-kernel - Re: [PATCH v2 1/2] x86/sgx: Add the missing ifdef for sgx_set

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Message-ID: <YR6Bs2twT4EK/jUK@google.com>
Date:   Thu, 19 Aug 2021 16:07:15 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>
Cc:     linux-sgx@...r.kernel.org, Shuah Khan <shuah@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Kai Huang <kai.huang@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] x86/sgx: Add the missing ifdef for
 sgx_set_attribute()

On Thu, Aug 19, 2021, Jarkko Sakkinen wrote:
> Similarly as sgx_virt_*, decorate sgx_set_attribute() with ifdef, so that
> calling it without appropraite config flags, will cause a compilation
> error, and not a linking error.
> 
> Fixes: b3754e5d3da3 ("x86/sgx: Move provisioning device creation out of SGX driver")
> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> ---
>  arch/x86/include/asm/sgx.h | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> index 05f3e21f01a7..38c397ef35a8 100644
> --- a/arch/x86/include/asm/sgx.h
> +++ b/arch/x86/include/asm/sgx.h
> @@ -365,6 +365,11 @@ struct sgx_sigstruct {
>   * comment!
>   */
>  
> +#if defined(CONFIG_X86_SGX) || defined(CONFIG_X86_SGX_KVM)

X86_SGX_KVM depends on X86_SGX

And rather than shuffle code, you can wrap all of the prototypes, which has the
added bonus of "documenting" the aformentioned dependency, e.g.

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
index 05f3e21f01a7..d5f3e617cc38 100644
--- a/arch/x86/include/asm/sgx.h
+++ b/arch/x86/include/asm/sgx.h
@@ -365,6 +365,7 @@ struct sgx_sigstruct {
  * comment!
  */

+#ifdef CONFIG_X86_SGX
 #ifdef CONFIG_X86_SGX_KVM
 int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
                     int *trapnr);
@@ -374,5 +375,6 @@ int sgx_virt_einit(void __user *sigstruct, void __user *token,

 int sgx_set_attribute(unsigned long *allowed_attributes,
                      unsigned int attribute_fd);
+#endif /* CONFIG_X86_SGX */

 #endif /* _ASM_X86_SGX_H */