On Fri, May 07, 2021 at 08:22:38AM +0200, Jan Beulich wrote:
> In this case compat headers don't get generated (and aren't needed).
> The changes made by 527922008bce ("x86: slim down hypercall handling
> when !PV32") also weren't quite sufficient for this case.
> 
> Try to limit #ifdef-ary by introducing two "fallback" #define-s.
> 
> Fixes: d23d792478db ("x86: avoid building COMPAT code when !HVM && !PV32")
> Reported-by: Andrew Cooper <[email protected]>
> Signed-off-by: Jan Beulich <[email protected]>
> 
> --- a/xen/arch/x86/pv/shim.c
> +++ b/xen/arch/x86/pv/shim.c
> @@ -34,8 +34,6 @@
>  #include <public/arch-x86/cpuid.h>
>  #include <public/hvm/params.h>
>  
> -#include <compat/grant_table.h>
> -
>  #undef virt_to_mfn
>  #define virt_to_mfn(va) _mfn(__virt_to_mfn(va))
>  
> @@ -300,8 +298,10 @@ static void write_start_info(struct doma
>                                            &si->console.domU.mfn) )
>          BUG();
>  
> +#ifdef CONFIG_PV32
>      if ( compat )
>          xlat_start_info(si, XLAT_start_info_console_domU);
> +#endif

Would it help the compiler logic if the 'compat' local variable was
made const?

I'm wondering if there's a way we can force DCE from the compiler and
avoid the ifdefs around the usage of compat.

Thanks, Roger.

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