linux-kernel - Re: [PATCH v8 01/11] x86/paravirt: Move halt paravirt calls under CONFIG

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Message-ID: <20211005201318.j3qg3swnovo7a3ot@treble>
Date:   Tue, 5 Oct 2021 13:13:18 -0700
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Paolo Bonzini <pbonzini@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Juergen Gross <jgross@...e.com>, Deep Shah <sdeep@...are.com>,
        VMware Inc <pv-drivers@...are.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Peter H Anvin <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 01/11] x86/paravirt: Move halt paravirt calls under
 CONFIG_PARAVIRT

On Mon, Oct 04, 2021 at 07:51:55PM -0700, Kuppuswamy Sathyanarayanan wrote:
> diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
> index c5ce9845c999..2a2ebf9af43e 100644
> --- a/arch/x86/include/asm/irqflags.h
> +++ b/arch/x86/include/asm/irqflags.h
> @@ -59,27 +59,15 @@ static inline __cpuidle void native_halt(void)
>  
>  #endif
>  
> -#ifdef CONFIG_PARAVIRT_XXL
> -#include <asm/paravirt.h>
> -#else
> -#ifndef __ASSEMBLY__
> -#include <linux/types.h>
> +#ifdef CONFIG_PARAVIRT
>  
> -static __always_inline unsigned long arch_local_save_flags(void)
> -{
> -	return native_save_fl();
> -}
> -
> -static __always_inline void arch_local_irq_disable(void)
> -{
> -	native_irq_disable();
> -}
> +# ifndef __ASSEMBLY__
> +# include <asm/paravirt.h>
> +# endif /* __ASSEMBLY__ */
>  
> -static __always_inline void arch_local_irq_enable(void)
> -{
> -	native_irq_enable();
> -}
> +#else /* ! CONFIG_PARAVIRT */
>  
> +# ifndef __ASSEMBLY__
>  /*
>   * Used in the idle loop; sti takes one instruction cycle
>   * to complete:
> @@ -97,6 +85,28 @@ static inline __cpuidle void halt(void)
>  {
>  	native_halt();
>  }
> +# endif /* __ASSEMBLY__ */
> +
> +#endif /* CONFIG_PARAVIRT */
> +
> +#ifndef CONFIG_PARAVIRT_XXL
> +#ifndef __ASSEMBLY__

There are a lot of '__ASSEMBLY__' #ifdefs which make this macro maze
extra hard to follow.  Folding in something like this would help a lot:

diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 2a2ebf9af43e..afecf7fa20d0 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -57,17 +57,12 @@ static inline __cpuidle void native_halt(void)
 	asm volatile("hlt": : :"memory");
 }
 
-#endif
-
 #ifdef CONFIG_PARAVIRT
 
-# ifndef __ASSEMBLY__
 # include <asm/paravirt.h>
-# endif /* __ASSEMBLY__ */
 
 #else /* ! CONFIG_PARAVIRT */
 
-# ifndef __ASSEMBLY__
 /*
  * Used in the idle loop; sti takes one instruction cycle
  * to complete:
@@ -85,9 +80,9 @@ static inline __cpuidle void halt(void)
 {
 	native_halt();
 }
-# endif /* __ASSEMBLY__ */
 
 #endif /* CONFIG_PARAVIRT */
+#endif /* __ASSEMBLY__ */
 
 #ifndef CONFIG_PARAVIRT_XXL
 #ifndef __ASSEMBLY__