Re: [Xen-devel] [PATCH v12 1/6] IOMMU: add a timeout parameter for device IOTLB invalidation

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

On June 27, 2016 4:29 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> >>> On 27.06.16 at 10:19, <quan.xu@xxxxxxxxx> wrote:
> > On June 27, 2016 4:03 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> >> >>> On 24.06.16 at 07:51, <quan.xu@xxxxxxxxx> wrote:
> >> > From: Quan Xu <quan.xu@xxxxxxxxx>
> >> >
> >> > The parameter 'iommu_dev_iotlb_timeout' specifies the timeout of
> >> > device IOTLB invalidation in milliseconds. By default, the timeout
> >> > is
> >> > 1000 milliseconds, which can be boot-time changed.
> >> >
> >> > We also confirmed with VT-d hardware team that 1 milliseconds is
> >> > large enough for VT-d IOMMU internal invalidation.
> >> >
> >> > the existing panic() is eliminated and we bubble up the timeout of
> >> > device IOTLB invalidation for further processing, as the PCI-e
> >> > Address Translation Services (ATS) mandates a timeout of
> >> > 60 seconds for device IOTLB invalidation. Obviously we can't spin
> >> > for
> >> > 60 seconds or otherwise Xen hypervisor hangs.
> >> >
> >> > Add a __must_check annotation. The followup patch titled 'VT-d
> >> > IOTLB/Context/IEC flush issue' addresses the __mustcheck.
> >> > That is the other callers of this routine (two or three levels up)
> >> > ignore the return code. This patch does not address this but the
> >> > other does.
> >>
> >> The patch itself looks okay,
> >
> > Jan, thanks for your review.
> >
> >> but I'm confused by this paragraph:
> >> There's no patch with the named title later in this series. And
> >> having gone through this patch I also don't see what remains to be
> >> addressed wrt the __must_check-s getting added here.
> >
> > This paragraph was added from a few rounds ago. I will drop it in next
> > version.
> 
> Well, if dropping this paragraph is all that's needed, 

Yes,

> I can do this while
> committing: Patches 1-3 appear to be ready to go in.
> 

Ah, that's great. Thanks.

Quan

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