Re: [Xen-devel] [PATCH v6 06/11] x86/hyperv: provide Hyper-V hypercall functions

[Wei Liu <wl@xxxxxxx>]

On Mon, Feb 03, 2020 at 02:48:42PM +0100, Jan Beulich wrote:
> On 03.02.2020 14:31, Wei Liu wrote:
> > On Mon, Feb 03, 2020 at 02:26:24PM +0100, Jan Beulich wrote:
> >> On 31.01.2020 18:49, Wei Liu wrote:
> >>> --- a/xen/arch/x86/mm.c
> >>> +++ b/xen/arch/x86/mm.c
> >>> @@ -375,9 +375,11 @@ void __init arch_init_memory(void)
> >>>      }
> >>>  #endif
> >>>  
> >>> -    /* Generate a symbol to be used in linker script */
> >>> +    /* Generate symbols to be used in linker script */
> >>>      asm ( ".equ FIXADDR_X_SIZE, %P0; .global FIXADDR_X_SIZE"
> >>>            :: "i" (FIXADDR_X_SIZE) );
> >>> +    asm ( ".equ HV_HCALL_PAGE, %P0; .global HV_HCALL_PAGE"
> >>> +          :: "i" (__fix_x_to_virt(FIX_X_HYPERV_HCALL)) );
> >>
> >> Would this even build without CONFIG_HYPERV_GUEST? In any event
> >> it doesn't belong here, but should go in a Hyper-V specific
> >> file.
> >>
> > 
> > Good catch. When I did my full build tests it was done with my previous
> > version.
> > 
> > I can move this to hyperv.c.
> > 
> >> Seeing you now need two of these, how about macro-izing the
> >> construct?
> > 
> > What name would you suggest? I'm thinking about GEN_XEN_LDS_SYMBOL.
> 
> In principle this isn't limiting things to use by xen.lds, so
> I'd prefer to not encode such in the name. asm_constant()? Or
> all caps if so preferred by others?

I am certainly okay with ASM_CONSTANT().

> 
> > And presumably I should put it in xen/lib.h?
> 
> Would be nice to have it there, but I'm afraid this is against
> what gcc documents. Hence if anything the P would need to be
> abstracted away as a per-arch thing. If you don't want to go
> this far, asm_defns.h might be the best fit among the x86
> headers.

OK. asm_defns.h it is. Arm doesn't need this for now anyway.

Wei.

> 
> Jan

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