Re: [PATCH 2/5] iommu/vt-d: Fix unaligned addresses for intel_flush_svm_range_dev()

Will Deacon
2021-01-08T14:10:19Z

Hi Lu,

On Fri, Jan 08, 2021 at 07:52:47AM +0800, Lu Baolu wrote:
> On 2021/1/6 9:09, Lu Baolu wrote:
> > On 2021/1/6 3:03, Will Deacon wrote:
> > > On Thu, Dec 31, 2020 at 08:53:20AM +0800, Lu Baolu wrote:
> > > > @@ -170,6 +172,22 @@ static void intel_flush_svm_range_dev
> > > > (struct intel_svm *svm, struct intel_svm_d
> > > >       }
> > > >   }
> > > > +static void intel_flush_svm_range_dev(struct intel_svm *svm,
> > > > +                      struct intel_svm_dev *sdev,
> > > > +                      unsigned long address,
> > > > +                      unsigned long pages, int ih)
> > > > +{
> > > > +    unsigned long shift = ilog2(__roundup_pow_of_two(pages));
> > > > +    unsigned long align = (1ULL << (VTD_PAGE_SHIFT + shift));
> > > > +    unsigned long start = ALIGN_DOWN(address, align);
> > > > +    unsigned long end = ALIGN(address + (pages <<
> > > > VTD_PAGE_SHIFT), align);
> > > > +
> > > > +    while (start < end) {
> > > > +        __flush_svm_range_dev(svm, sdev, start, align >>
> > > > VTD_PAGE_SHIFT, ih);
> > > > +        start += align;
> > > > +    }
> > > > +}
> > >
> > > Given that this only seems to be called from
> > > intel_invalidate_range(), which
> > > has to compute 'pages' only to have it pulled apart again here,
> > > perhaps it
> > > would be cleaner for intel_flush_svm_range() to take something like an
> > > 'order' argument instead?
> > >
> > > What do you think?
> >
> > We need to clean up here. It's duplicate with the qi_flush_piotlb()
> > helper. I have a patch under testing for this. I will post it for review
> > later.
>
> I'm sorry, above reply is a little vague.
>
> I meant to say, let's take 'pages' as the argument. We are going to use
> qi_flush_piotlb() here to avoid duplicate QI interactions. The
> qi_flush_piotlb() helper also takes 'pages', so keep 'pages' here will
> make things easier.
>
> My cleanup patch is for v5.12. Can you please take this for v5.11?

Ah sorry, I didn't realise that was your plan. Please just include this
patch in a series of 2 when you post a fixed version of the trace event
removal and then I'll queue them up next week, as I've already prepared
the pull for today.

Apologies,

Will