Re: [Xen-devel] [PATCH v3 1/2] VT-d: Reduce spin timeout to 1ms, which can be boot-time changed.

["Xu, Quan" <quan.xu@xxxxxxxxx>]

>On 15.12.2015 at 5:18pm, <JBeulich@xxxxxxxx> wrote:
> >>> On 15.12.15 at 09:35, <quan.xu@xxxxxxxxx> wrote:
> >>  On 14.12.2015 at 5:14pm, <JBeulich@xxxxxxxx> wrote:
> >> >>> On 12.12.15 at 14:21, <quan.xu@xxxxxxxxx> wrote:
> >> > @@ -167,10 +172,12 @@ static int queue_invalidate_wait(struct iommu
> >> *iommu,
> >> >          start_time = NOW();
> >> >          while ( poll_slot != QINVAL_STAT_DONE )
> >> >          {
> >> > -            if ( NOW() > (start_time + DMAR_OPERATION_TIMEOUT) )
> >> > +            if ( NOW() > (start_time + IOMMU_QI_TIMEOUT) )
> >> >              {
> >> >                  print_qi_regs(iommu);
> >> > -                panic("queue invalidate wait descriptor was not
> >> executed");
> >> > +                dprintk(XENLOG_WARNING VTDPREFIX,
> >> > +                        "Queue invalidate wait descriptor was
> >> timeout.\n");
> >> > +                return -ETIMEDOUT;
> >> >              }
> >>
> >> Without the v2 discussion even having finished, and without you
> >> having taken care of v2 comments here, I don't see much value in this v3.
> >>
> >
> > I should check for _any_ kind_of_error and
> > all_the_way_up_the_call_trees in [patch 1/2].
> 
> As said, perhaps better in patch 1/3.

Agreed.

> 
> > 1. For _any_ kind_of_error,
> > now it includes '-ETIMEDOUT' and '-EOPNOTSUPP'. I should check the
> > return code, if it is _not_ZERO.
> > The callers need to also either pass it on or deal with it. (if the
> > return code is _not_ZERO, it should check whether it is '-ETIMEDOUT'
> > in [patch 2/2])
> >
> > 2. all_the_way_up_the_call_trees
> >
> > .i.e
> > enable_intremap()
> > |--iommu_flush_iec_global()
> >   |--__iommu_flush_iec()
> >     |--invalidate_sync()
> >
> > In enable_intremap(), if iommu_flush_iec_global()  is failed,
> > enable_intremap() should deal with this error and then return.
> 
> Yes.

Good..

Quan




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