Re: [Xen-devel] [PATCH v10 2/3] vt-d: synchronize for Device-TLB flush one by one

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

On May 17, 2016 8:37 PM, Jan Beulich <JBeulich@xxxxxxxx>wrote:
> >>> On 22.04.16 at 12:54, <quan.xu@xxxxxxxxx> wrote:
> > --- a/xen/drivers/passthrough/vtd/qinval.c
> > +++ b/xen/drivers/passthrough/vtd/qinval.c
> > @@ -33,6 +33,8 @@ integer_param("vtd_qi_timeout", vtd_qi_timeout);
> >
> >  #define IOMMU_QI_TIMEOUT (vtd_qi_timeout * MILLISECS(1))
> >
> > +static int invalidate_sync(struct iommu *iommu);
> 
> __must_check?
> 

Yes, I will add it.


> > -static void queue_invalidate_iotlb(struct iommu *iommu,
> > -    u8 granu, u8 dr, u8 dw, u16 did, u8 am, u8 ih, u64 addr)
> > +static int __must_check queue_invalidate_iotlb_sync(struct iommu
> *iommu,
> > +                                                    u8 granu, u8 dr, u8 dw,
> > +                                                    u16 did, u8 am, u8 ih,
> > +                                                    u64 addr)
> >  {
> >      unsigned long flags;
> >      unsigned int index;
> > @@ -133,10 +141,12 @@ static void queue_invalidate_iotlb(struct iommu
> *iommu,
> >      unmap_vtd_domain_page(qinval_entries);
> >      qinval_update_qtail(iommu, index);
> >      spin_unlock_irqrestore(&iommu->register_lock, flags);
> > +
> > +    return invalidate_sync(iommu);
> >  }
> 
> With this, ...
> 
> > @@ -346,9 +353,13 @@ static int flush_iotlb_qi(
> >          if (cap_read_drain(iommu->cap))
> >              dr = 1;
> >          /* Need to conside the ih bit later */
> > -        queue_invalidate_iotlb(iommu,
> > -                               type >> DMA_TLB_FLUSH_GRANU_OFFSET, dr,
> > -                               dw, did, size_order, 0, addr);
> > +        ret = queue_invalidate_iotlb_sync(iommu,
> > +                                          type >> 
> > DMA_TLB_FLUSH_GRANU_OFFSET,
> > +                                          dr, dw, did, size_order, 0, 
> > addr);
> > +
> > +        if ( ret )
> > +            return ret;
> > +
> >          if ( flush_dev_iotlb )
> >              ret = dev_invalidate_iotlb(iommu, did, addr, size_order, type);
> >          rc = invalidate_sync(iommu);
> 
> ... why does this invalidate_sync() not go away?
> 

Oh, it is your suggestion -- leaving the existing logic as is would be better - 
best effort
invalidation even when an error has occurred.

http://lists.xenproject.org/archives/html/xen-devel/2016-04/msg00523.html

Quan




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