On Wed, Oct 28, 2015 at 06:48:41PM +0100, Eric Auger wrote:
> On 10/28/2015 06:37 PM, Alex Williamson wrote:
> > Ok, so with hopefully correcting my understand of what this does, isn't
> > this effectively the same:
> >
> > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> > index 57d8c37..7db4f5a 100644
> > --- a/drivers/vfio/vfio_iommu_type1.c
> > +++ b/drivers/vfio/vfio_iommu_type1.c
> > @@ -403,13 +403,19 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, stru
> > static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
> > {
> > struct vfio_domain *domain;
> > - unsigned long bitmap = PAGE_MASK;
> > + unsigned long bitmap = ULONG_MAX;
> >
> > mutex_lock(&iommu->lock);
> > list_for_each_entry(domain, &iommu->domain_list, next)
> > bitmap &= domain->domain->ops->pgsize_bitmap;
> > mutex_unlock(&iommu->lock);
> >
> > + /* Some comment about how the IOMMU API splits requests */
> > + if (bitmap & ~PAGE_MASK) {
> > + bitmap &= PAGE_MASK;
> > + bitmap |= PAGE_SIZE;
> > + }
> > +
> > return bitmap;
> > }
> Yes, to me it is indeed the same
> >
> > This would also expose to the user that we're accepting PAGE_SIZE, which
> > we weren't before, so it was not quite right to just let them do it
> > anyway. I don't think we even need to get rid of the WARN_ONs, do we?
> > Thanks,
>
> The end-user might be afraid of those latter. Personally I would get rid
> of them but that's definitively up to you.
I think Alex's point is that the WARN_ON's won't trigger with this patch,
because he clears those lower bits in the bitmap.
Will
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