samsung_sm8750/android_kernel_samsung_sm8750
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

iommu: Handle race with default domain setup

Browse Source 
commit b46064a18810bad3aea089a79993ca5ea7a3d2b2 upstream.

It turns out that deferred default domain creation leaves a subtle
race window during iommu_device_register() wherein a client driver may
asynchronously probe in parallel and get as far as performing DMA API
operations with dma-direct, only to be switched to iommu-dma underfoot
once the default domain attachment finally happens, with obviously
disastrous consequences. Even the wonky of_iommu_configure() path is at
risk, since iommu_fwspec_init() will no longer defer client probe as the
instance ops are (necessarily) already registered, and the "replay"
iommu_probe_device() call can see dev->iommu_group already set and so
think there's nothing to do either.

Fortunately we already have the right tool in the right place in the
form of iommu_device_use_default_domain(), which just needs to ensure
that said default domain is actually ready to *be* used. Deferring the
client probe shouldn't have too much impact, given that this only
happens while the IOMMU driver is probing, and thus due to kick the
deferred probe list again once it finishes.

Reported-by: Charan Teja Kalla <quic_charante@quicinc.com>
Fixes: 98ac73f99bc4 ("iommu: Require a default_domain for all iommu drivers")
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/e88b94c9b575034a2c98a48b3d383654cbda7902.1740753261.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
This commit is contained in:
Robin Murphy
2025-02-28 15:46:30 +00:00
committed by Greg Kroah-Hartman
parent a1723e9c53
commit a6dbcf69d4
1 changed files with 18 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/iommu/iommu.c
View File

@@ -566,6 +566,18 @@ int iommu_probe_device(struct device *dev)
mutex_lock(&iommu_probe_device_lock);
ret = __iommu_probe_device(dev, NULL);
mutex_unlock(&iommu_probe_device_lock);
/*
* The dma_configure replay paths need bus_iommu_probe() to
* finish before they can call arch_setup_dma_ops()
*/
if (IS_ENABLED(CONFIG_IOMMU_DMA) && !ret && dev->iommu_group) {
mutex_lock(&dev->iommu_group->mutex);
if (!dev->iommu_group->default_domain &&
!dev_iommu_ops(dev)->set_platform_dma_ops)
ret = -EPROBE_DEFER;
mutex_unlock(&dev->iommu_group->mutex);
}
if (ret)
return ret;
@@ -3149,6 +3161,12 @@ int iommu_device_use_default_domain(struct device *dev)
return 0;
mutex_lock(&group->mutex);
/* We may race against bus_iommu_probe() finalising groups here */
if (IS_ENABLED(CONFIG_IOMMU_DMA) && !group->default_domain &&
!dev_iommu_ops(dev)->set_platform_dma_ops) {
ret = -EPROBE_DEFER;
goto unlock_out;
}
if (group->owner_cnt) {
if (group->owner || !iommu_is_default_domain(group) ||
!xa_empty(&group->pasid_array)) {