On 2023-12-14 4:51 pm, Jean-Philippe Brucker wrote:
On Wed, Dec 13, 2023 at 05:17:59PM +0000, Robin Murphy wrote:
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 27a167f4cd3e..d808c8dcf5cb 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1724,25 +1724,20 @@ static const struct dma_map_ops iommu_dma_ops = {
.opt_mapping_size = iommu_dma_opt_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)) {
...
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 824989874dee..43f630d0530e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -560,10 +560,10 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
if (list_empty(&group->entry))
list_add_tail(&group->entry, group_list);
}
- mutex_unlock(&group->mutex);
- if (dev_is_pci(dev))
- iommu_dma_set_pci_32bit_workaround(dev);
+ iommu_setup_dma_ops(dev);
With Intel VT-d (QEMU emulation) I get a crash in iommu_setup_dma_ops()
because at this point group->domain and group->default_domain are still
NULL, group_list is non-NULL.
Ugh, clearly I'd manage to confuse myself, since what I wrote in the
changelog isn't even right...
Taking yet another look, there's not actually one single place we can do
this right now which will work in a manageable way for all cases. With 2
or 3 more levels of mess unpicked it's going to clean up much further
(it's also becoming clear that iommu-dma wants better separation of its
own per-device and per-domain bits), but for the immediate task in this
series of finally getting out of arch code, I guess that continuing to
echo the current probe_finalize flows is going to be safest. Something
like the diff below (but I'll have a further think about it with a fresh
head tomorrow).
Thanks,
Robin.
----->8-----
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 8972b7f22a9a..ba4cd5251205 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -562,7 +562,8 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
list_add_tail(&group->entry, group_list);
}
- iommu_setup_dma_ops(dev);
+ if (group->default_domain)
+ iommu_setup_dma_ops(dev);
mutex_unlock(&group->mutex);
@@ -1992,6 +1993,8 @@ int bus_iommu_probe(const struct bus_type *bus)
mutex_unlock(&group->mutex);
return ret;
}
+ for_each_group_device(group, gdev)
+ iommu_setup_dma_ops(gdev->dev);
mutex_unlock(&group->mutex);
/*
@@ -3217,18 +3220,9 @@ static ssize_t iommu_group_store_type(struct iommu_group *group,
if (ret)
goto out_unlock;
- /*
- * Release the mutex here because ops->probe_finalize() call-back of
- * some vendor IOMMU drivers calls arm_iommu_attach_device() which
- * in-turn might call back into IOMMU core code, where it tries to take
- * group->mutex, resulting in a deadlock.
- */
- mutex_unlock(&group->mutex);
-
/* Make sure dma_ops is appropriatley set */
for_each_group_device(group, gdev)
- iommu_group_do_probe_finalize(gdev->dev);
- return count;
+ iommu_setup_dma_ops(gdev->dev);
out_unlock:
mutex_unlock(&group->mutex);
