Re: [Xen-devel] [PATCH 5/9] x86: relocate pvh_info

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Jan 18, 2018 at 06:16:48PM +0000, Wei Liu wrote:
> diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
> index 0f652cea11..2f94c286d5 100644
> --- a/xen/arch/x86/boot/head.S
> +++ b/xen/arch/x86/boot/head.S
> @@ -414,6 +414,7 @@ __pvh_start:
>  
>          /* Set trampoline_phys to use mfn 1 to avoid having a mapping at VA 
> 0 */
>          movw    $0x1000, sym_esi(trampoline_phys)
> +        xor     %eax, %eax /* Needed by reloc.c */

I would rather do:

movl $XEN_HVM_START_MAGIC_VALUE,%eax

Or:

mov (%ebx),%eax

So that...

> -multiboot_info_t __stdcall *reloc(u32 mb_magic, u32 mbi_in, u32 trampoline)
> +void __stdcall *reloc(u32 magic, u32 in, u32 trampoline)
>  {
>      alloc = trampoline;
>  
> -    if ( mb_magic == MULTIBOOT2_BOOTLOADER_MAGIC )
> -        return mbi2_reloc(mbi_in);
> +#ifdef CONFIG_PVH_GUEST
> +    if ( magic == 0 )

... here you can do magic == XEN_HVM_START_MAGIC_VALUE.

> +        return pvh_info_reloc(in);
> +    else
> +#endif
> +    if ( magic == MULTIBOOT2_BOOTLOADER_MAGIC )
> +        return mbi2_reloc(in);
>      else
> -        return mbi_reloc(mbi_in);
> +        return mbi_reloc(in);

A 'switch ( magic )' would be better here IMHO.

Thanks, Roger.

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