Re: [PATCH 8/18 V2]: PVH xen: domain creation code changes

[Mukesh Rathor <mukesh.rathor@oracle.com>]

On Mon, 18 Mar 2013 11:57:43 +0000
"Jan Beulich" <JBeulich@suse.com> wrote:

> >>> On 16.03.13 at 01:36, Mukesh Rathor <mukesh.rathor@oracle.com>
> >>> wrote:
> > --- a/xen/include/asm-x86/system.h
> > +++ b/xen/include/asm-x86/system.h
> > @@ -4,9 +4,15 @@
> >  #include <xen/lib.h>
> >  #include <asm/bitops.h>
> >  
> > +/* We need vcpu because during context switch, going from pure PV
> > to PVH,
> > + * in save_segments(), current has been updated to next, and no
> > longer pointing
> > + * to the pure PV. Note: for PVH, we update regs->selectors on
> > each vmexit */ #define read_segment_register(vcpu, regs,
> > name)                 \ ({  u16
> > __sel;                                                  \
> > -    asm volatile ( "movw %%" STR(name) ",%0" : "=r" (__sel) );  \
> > +    if (is_pvh_vcpu(vcpu))
> > \
> > +        __sel = regs->name;                                     \
> > +    else                                                         \
> > +        asm volatile ( "movw %%" STR(name) ",%0" :
> > "=r" (__sel) );  \
> > __sel;                                                      \ })
> 
> In a generic macro like this, please make sure you evaluate each
> argument exactly once, and you properly parenthesize all uses of
> macro arguments.

Hmm... at a loss. The only think I'm able to come up with here is
paranthesis around regs, and spaces in the if statement. Both vcpu and
regs are used only once.