On Wed, Jun 16, 2021 at 06:02:39PM +0100, Robin Murphy wrote:

quoted

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index c62e19bed302..175f8eaeb5b3 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -1322,7 +1322,9 @@ void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit)
  	if (domain->type == IOMMU_DOMAIN_DMA) {
  		if (iommu_dma_init_domain(domain, dma_base, dma_limit, dev))
  			goto out_err;
-		dev->dma_ops = &iommu_dma_ops;
+		set_dma_ops(dev, &iommu_dma_ops);
+	} else {
+		set_dma_ops(dev, NULL);

I'm not keen on moving this here, since iommu-dma only knows that its own
ops are right for devices it *is* managing; it can't assume any particular
ops are appropriate for devices it isn't. The idea here is that
arch_setup_dma_ops() may have already set the appropriate ops for the
non-IOMMU case, so if the default domain type is passthrough then we leave
those in place.

For example, I do still plan to revisit my conversion of arch/arm someday,
at which point I'd have to undo this for that reason.

Makes sense, I'll remove this bit.

Simplifying the base and size arguments is of course fine, but TBH I'd say
rip the whole bloody lot out of the arch_setup_dma_ops() flow now. It's a
considerable faff passing them around for nothing but a tenuous sanity check
in iommu_dma_init_domain(), and now that dev->dma_range_map is a common
thing we should expect that to give us any relevant limitations if we even
still care.

So I started working on this but it gets too bulky for a preparatory
patch. Dropping the parameters from arch_setup_dma_ops() seems especially
complicated because arm32 does need the size parameter for IOMMU mappings
and that value falls back to the bus DMA mask or U32_MAX in the absence of
dma-ranges. I could try to dig into this for a separate series.

Even only dropping the parameters from iommu_setup_dma_ops() isn't
completely trivial (8 files changed, 55 insertions(+), 36 deletions(-)
because we still need the lower IOVA limit from dma_range_map), so I'd
rather send it separately and have it sit in -next for a while.

Thanks,
Jean

That said, those are all things which can be fixed up later if the series is
otherwise ready to go and there's still a chance of landing it for 5.14. If
you do have any other reason to respin, then I think the x86 probe_finalize
functions simply want an unconditional set_dma_ops(dev, NULL) before the
iommu_setup_dma_ops() call.

Cheers,
Robin.

quoted

  	}
  	return;

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 85f18342603c..8d866940692a 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c

@@ -5165,15 +5165,7 @@ static void intel_iommu_release_device(struct device *dev)
  static void intel_iommu_probe_finalize(struct device *dev)
  {
-	dma_addr_t base = IOVA_START_PFN << VTD_PAGE_SHIFT;
-	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
-	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
-
-	if (domain && domain->type == IOMMU_DOMAIN_DMA)
-		iommu_setup_dma_ops(dev, base,
-				    __DOMAIN_MAX_ADDR(dmar_domain->gaw));
-	else
-		set_dma_ops(dev, NULL);
+	iommu_setup_dma_ops(dev, 0, U64_MAX);
  }
  static void intel_iommu_get_resv_regions(struct device *device,

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