Re: [Xen-devel] [PATCH 1/9] x86/hypercall: Move some of the hvm hypercall infrastructure into hypercall.h

[Julien Grall <julien.grall@xxxxxxx>]

Hi Jan,

On 02/08/16 14:28, Jan Beulich wrote:
> > > > On 02.08.16 at 15:14, <andrew.cooper3@xxxxxxxxxx> wrote:
> > On 02/08/16 13:50, Jan Beulich wrote:
> > > > > > On 18.07.16 at 11:51, <andrew.cooper3@xxxxxxxxxx> wrote:
> > > > --- a/xen/include/asm-x86/hypercall.h
> > > > +++ b/xen/include/asm-x86/hypercall.h
> > > > @@ -5,9 +5,21 @@
> > > >  #ifndef __ASM_X86_HYPERCALL_H__
> > > >  #define __ASM_X86_HYPERCALL_H__
> > > >
> > > > +#include <xen/types.h>
> > > >  #include <public/physdev.h>
> > > > +#include <public/event_channel.h>
> > > Why?
> > You snipped the commit message, which justifies why.  This header file
> > cannot currently be included in isolation, and I need it to be.
> Ah, that sentence there also relates to this addition.
>
> > > >  #include <public/arch-x86/xen-mca.h> /* for do_mca */
> > > > -#include <xen/types.h>
> > > > +
> > > > +typedef unsigned long hypercall_fn_t(
> > > > +    unsigned long, unsigned long, unsigned long,
> > > > +    unsigned long, unsigned long, unsigned long);
> > > Wouldn't this better go into xen/hypercall.h?
> > It is architecture specific.
> >
> > ARM's version is
> >
> > typedef register_t (*arm_hypercall_fn_t)(
> >     register_t, register_t, register_t, register_t, register_t);
> Which is bogus - they're lucky we so far don't have any 6-argument
> hypercalls. Or the other way around - we could limit hypercalls to
> just five arguments (for now) on x86 too, allowing things to get
> unified. Anyway - that probably goes too far right now, so feel free
> to add my ack to the patch.
I am not sure why you think we are lucky on ARM. The hypercall has been 
defined on ARM to support up to 5 arguments (public/arch-arm.h):
"A hypercall can take up to 5 arguments. These are passed in
registers, the first argument in x0/r0 (for arm64/arm32 guests
respectively irrespective of whether the underlying hypervisor is
32- or 64-bit), the second argument in x1/r1, the third in x2/r2,
the forth in x3/r3 and the fifth in x4/r4."

So the prototype matches the ABI.

Regards,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel