iommu/dma: Centralise iommu_setup_dma_ops()

It's somewhat hard to see, but arm64's arch_setup_dma_ops() should only
ever call iommu_setup_dma_ops() after a successful iommu_probe_device(),
which means there should be no harm in achieving the same order of
operations by running it off the back of iommu_probe_device() itself.
This then puts it in line with the x86 and s390 .probe_finalize bodges,
letting us pull it all into the main flow properly. As a bonus this lets
us fold in and de-scope the PCI workaround setup as well.

At this point we can also then pull the call up inside the group mutex,
and avoid having to think about whether iommu_group_store_type() could
theoretically race and free the domain if iommu_setup_dma_ops() ran just
*before* iommu_device_use_default_domain() claims it... Furthermore we
replace one .probe_finalize call completely, since the only remaining
implementations are now one which only needs to run once for the initial
boot-time probe, and two which themselves render that path unreachable.

This leaves us a big step closer to realistically being able to unpick
the variety of different things that iommu_setup_dma_ops() has been
muddling together, and further streamline iommu-dma into core API flows
in future.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> # For Intel IOMMU
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/bebea331c1d688b34d9862eefd5ede47503961b8.1713523152.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 6 insertions, 12 deletions

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index c827ed690f1f..bc1490bd4f7a 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1741,25 +1741,20 @@ static const struct dma_map_ops iommu_dma_ops = {
 	.max_mapping_size       = iommu_dma_max_mapping_size,
 };
 
-/*
- * The IOMMU core code allocates the default DMA domain, which the underlying
- * IOMMU driver needs to support via the dma-iommu layer.
- */
-void iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 dma_limit)
+void iommu_setup_dma_ops(struct device *dev)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
 
-	if (!domain)
-		goto out_err;
+	if (dev_is_pci(dev))
+		dev->iommu->pci_32bit_workaround = !iommu_dma_forcedac;
 
-	/*
-	 * The IOMMU core code allocates the default DMA domain, which the
-	 * underlying IOMMU driver needs to support via the dma-iommu layer.
-	 */
 	if (iommu_is_dma_domain(domain)) {
 		if (iommu_dma_init_domain(domain, dev))
 			goto out_err;
 		dev->dma_ops = &iommu_dma_ops;
+	} else if (dev->dma_ops == &iommu_dma_ops) {
+		/* Clean up if we've switched *from* a DMA domain */
+		dev->dma_ops = NULL;
 	}
 
 	return;
@@ -1767,7 +1762,6 @@ out_err:
 	 pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
 		 dev_name(dev));
 }
-EXPORT_SYMBOL_GPL(iommu_setup_dma_ops);
 
 static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 		phys_addr_t msi_addr, struct iommu_domain *domain)