Re: [Xen-devel] [PATCH v2 02/30] xen/x86: remove XENFEAT_hvm_pirqs for PVHv2 guests

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

On Wed, Sep 28, 2016 at 10:03:21AM -0600, Jan Beulich wrote:
> >>> On 27.09.16 at 17:56, <roger.pau@xxxxxxxxxx> wrote:
> > On PVHv2 guests we explicitly want to use native methods for routing
> > interrupts.
> > 
> > Introduce a new XEN_X86_EMU_USE_PIRQ to notify Xen whether a HVM guest can
> > route physical interrupts (even from emulated devices) over event channels.
> 
> So you specifically want this new flag off for PVHv2 guests? Based on
> just this description I did get the opposite impression...

Yes, that's right, I don't want PVHv2 guests to know anything about PIRQs. I 
don't really know how to reword this, what about:

"PVHv2 guests, unlike HVM guests, won't have the option to route interrupts 
from physical or emulated devices over event channels using PIRQs. This 
applies to both DomU and Dom0 PVHv2 guests.

Introduce a new XEN_X86_EMU_USE_PIRQ to notify Xen whether a HVM guest can
route physical interrupts (even from emulated devices) over event channels, 
and is thus allowed to use some of the PHYSDEV ops."

> > --- a/xen/arch/x86/hvm/hvm.c
> > +++ b/xen/arch/x86/hvm/hvm.c
> > @@ -4117,6 +4117,8 @@ static long hvm_memory_op(int cmd, 
> > XEN_GUEST_HANDLE_PARAM(void) arg)
> >  
> >  static long hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
> >  {
> > +    struct domain *d = current->domain;
> 
> currd please.
> 
> > @@ -4128,7 +4130,9 @@ static long hvm_physdev_op(int cmd, 
> > XEN_GUEST_HANDLE_PARAM(void) arg)
> >      case PHYSDEVOP_eoi:
> >      case PHYSDEVOP_irq_status_query:
> >      case PHYSDEVOP_get_free_pirq:
> > -        return do_physdev_op(cmd, arg);
> > +        return ((d->arch.emulation_flags & XEN_X86_EMU_USE_PIRQ) ||
> > +               is_pvh_vcpu(current)) ?
> 
> is_pvh_domain(currd)

Thanks, it's fixed now. I've also taken the opportunity to fixing two other 
instances of current and current->domain.

Roger.

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