Re: [Xen-devel] [PATCH v4 04/10] vt-d: propagate IOMMU Device-TLB flush error up to IOMMU unmapping.

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

On May 10, 2016 4:51 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> >>> On 06.05.16 at 10:54, <quan.xu@xxxxxxxxx> wrote:
> > Propagate the IOMMU Device-TLB flush error up to IOMMU unmapping.
> >
> > Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
> > Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> 
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> but note ...
> 
> > @@ -1766,9 +1769,7 @@ static int intel_iommu_unmap_page(struct
> domain *d, unsigned long gfn)
> >      if ( iommu_passthrough && is_hardware_domain(d) )
> >          return 0;
> >
> > -    dma_pte_clear_one(d, (paddr_t)gfn << PAGE_SHIFT_4K);
> > -
> > -    return 0;
> > +    return dma_pte_clear_one(d, (paddr_t)gfn << PAGE_SHIFT_4K);
> >  }
> 
> ... how you lose the __must_check here, since
> intel_iommu_unmap_page() isn't __must_check (which we said you may skip
> as long as the common code wrapper has it, but in the context here I'm no
> longer convinced skipping this at any layer is a good idea, as that makes
> validation of the call trees more difficult).
> (This is just a remark regarding the comment on the earlier patch, i.e. not
> something needing any further change here.)
> 


I'll be bold to add __must_check..
Quan


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