Re: [Xen-devel] [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

Luis R. Rodriguez
2014-12-11T21:05:47Z

On Thu, Dec 11, 2014 at 11:09:42AM +0000, David Vrabel wrote:
> On 10/12/14 23:51, Andy Lutomirski wrote:
> > On Wed, Dec 10, 2014 at 3:34 PM, Luis R. Rodriguez
> > All that being said, this is IMO a bit gross. You've added a bunch of
> > asm that's kind of like a parallel error_exit, and the error entry and
> > exit code is hairy enough that this scares me. Can you do this mostly
> > in C instead? This would look a nicer if it could be:
>
> I abandoned my initial attempt that looked like this because I thought
> it was gross too.
>
> > call xen_evtchn_do_upcall
> > popq %rsp
> > CFI_DEF_CFA_REGISTER rsp
> > decl PER_CPU_VAR(irq_count)
> > + call xen_end_upcall
> > jmp error_exit
> >
> > Where xen_end_upcall would be witten in C, nokprobes and notrace (if
> > needed) and would check pt_regs and whatever else and just call
> > schedule if needed?
>
> Oh that's a good idea, thanks!

David, are you going to respin yourself with the goal to get this upstream?
If so I can move on with life on other matters.

Luis