Re: [PATCH 3/3] x86: Delete str()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 28.07.2023 21:43, Andrew Cooper wrote:
> This is used in an assertion only, which is somewhat dubious to begin with and
> won't surivive the x86-S work (where TR will become be a NUL selector).

I'm kind of okay with the removal, but I can't read anything like the
above out of the doc. Can you point me at where this is said?

Jan

> Delete it now.  This avoids many cases where as a global symbol, it shadows
> local string variables.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> CC: Wei Liu <wl@xxxxxxx>
> CC: Roberto Bagnara <roberto.bagnara@xxxxxxxxxxx>
> CC: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> ---
>  xen/arch/x86/hvm/svm/svm.c      | 2 --
>  xen/arch/x86/include/asm/desc.h | 9 ---------
>  2 files changed, 11 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index 56cb2f61bb75..4d29ad3bc36a 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -1614,8 +1614,6 @@ static int _svm_cpu_up(bool bsp)
>      /* Initialize OSVW bits to be used by guests */
>      svm_host_osvw_init();
>  
> -    /* Minimal checking that enough CPU setup was done by now. */
> -    ASSERT(str() == TSS_SELECTOR);
>      svm_vmsave_pa(per_cpu(host_vmcb, cpu));
>  
>      return 0;
> diff --git a/xen/arch/x86/include/asm/desc.h b/xen/arch/x86/include/asm/desc.h
> index 225a864c483e..a1e0807d97ed 100644
> --- a/xen/arch/x86/include/asm/desc.h
> +++ b/xen/arch/x86/include/asm/desc.h
> @@ -238,15 +238,6 @@ static inline void ltr(unsigned int sel)
>      __asm__ __volatile__ ( "ltr %w0" :: "rm" (sel) : "memory" );
>  }
>  
> -static inline unsigned int str(void)
> -{
> -    unsigned int sel;
> -
> -    __asm__ ( "str %0" : "=r" (sel) );
> -
> -    return sel;
> -}
> -
>  #endif /* !__ASSEMBLY__ */
>  
>  #endif /* __ARCH_DESC_H */