Re: [Xen-devel] [PATCH v2 09/11] IOMMU: propagate IOMMU Device-TLB flush error up to IOMMU suspending

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

 On April 29, 2016 10:21 AM, Tian, Kevin <kevin.tian@xxxxxxxxx> wrote:
> > From: Xu, Quan
> > Sent: Friday, April 29, 2016 12:09 AM
> > On April 28, 2016 11:12 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> > > >>> On 28.04.16 at 17:03, <quan.xu@xxxxxxxxx> wrote:
> > > > On April 28, 2016 10:36 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> > > >> >>> On 28.04.16 at 16:14, <quan.xu@xxxxxxxxx> wrote:
> > > >> > On April 25, 2016 7:53 PM, Jan Beulich <JBeulich@xxxxxxxx>
> wrote:
> > > >> >> >>> On 18.04.16 at 16:00, <quan.xu@xxxxxxxxx> wrote:
> > > >> >> > --- a/xen/drivers/passthrough/vtd/iommu.c
> > > >> >> > +++ b/xen/drivers/passthrough/vtd/iommu.c
> > > >> >
> > > >> >
> > > >> >> > -static void iommu_flush_all(void)
> > > >> >> > +static int iommu_flush_all(void)
> > > >> >>
> > > >> >> __must_check
> > > >> >>
> > > >> >
> > > >> > The iommu_flush_all() is also called in
> > > >> > intel_iommu_hwdom_init() and vtd_crash_shutdown().
> > > >> > As we were on the same page, we can ignore the error code
> > > >> > propagation for these two call trees.
> > > >>
> > > >> I don't know what you're referring to here with "we were on the
> > > >> same
> > > page".
> > > > I
> > > >> don't think I've ever agreed (in the context of this series) to
> > > >> ignore any
> > > > error
> > > >> returns.
> > > >>
> > > >
> > > >
> > > > Look at the below link.
> > > > http://lists.xenproject.org/archives/html/xen-devel/2016-02/msg032
> > > > 34.h
> > > > tml
> > >
> > > Which still talks about (conditionally) logging messages, not ignoring of
> errors.
> > >
> >
> > Sorry, check it again.
> > in intel_iommu_hwdom_init() and  vtd_crash_shutdown(), I still need to
> > log messages as:
> >
> > if ( iommu_flush_all() )
> >      printk()
> >
> > ?
> >
> > Thanks for your patience.
> > Quan
> 
> Yes, but please make sure you only print once to be useful.
>

 
Thanks.
Now I check the status in caller to make the print include caller which is 
failed, instead print in iommu_flush_all().
i.e., 
vtd_crash_shutdown()
{
..
    if ( iommu_flush_all() )
        printk(XENLOG_WARNING VTDPREFIX
               " vtd_crash_shutdown: IOMMU flush all failed.\n");
..
}

I am afraid I still don't get the point. To be honest, in such a fix,
The print is not so useful to me ( Correct me, I will continue to enhance it).

Quan
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