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 4:03 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.

Quan

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