6.6-stable review patch. If anyone has any objections, please let me know.
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From: Yi Liu yi.l.liu@intel.com
[ Upstream commit b025dea63cded0d82bccd591fa105d39efc6435d ]
There is no error handling now in __iommu_set_group_pasid(), it relies on its caller to loop all the devices to undo the pasid attachment. This is not self-contained and has drawbacks. It would result in unnecessary remove_dev_pasid() calls on the devices that have not been attached to the new domain. But the remove_dev_pasid() callback would get the new domain from the group->pasid_array. So for such devices, the iommu driver won't find the attachment under the domain, hence unable to do cleanup. This may not be a real problem today. But it depends on the implementation of the underlying iommu driver. e.g. the intel iommu driver would warn for such devices. Such warnings are unnecessary.
To solve the above problem, it is necessary to handle the error within __iommu_set_group_pasid(). It only loops the devices that have attached to the new domain, and undo it.
Fixes: 16603704559c ("iommu: Add attach/detach_dev_pasid iommu interfaces") Suggested-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Yi Liu yi.l.liu@intel.com Reviewed-by: Lu Baolu baolu.lu@linux.intel.com Link: https://lore.kernel.org/r/20240328122958.83332-2-yi.l.liu@intel.com Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/iommu.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 3a67e636287a7..3f1029c0825e9 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3369,15 +3369,26 @@ EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed); static int __iommu_set_group_pasid(struct iommu_domain *domain, struct iommu_group *group, ioasid_t pasid) { - struct group_device *device; - int ret = 0; + struct group_device *device, *last_gdev; + int ret;
for_each_group_device(group, device) { ret = domain->ops->set_dev_pasid(domain, device->dev, pasid); if (ret) - break; + goto err_revert; }
+ return 0; + +err_revert: + last_gdev = device; + for_each_group_device(group, device) { + const struct iommu_ops *ops = dev_iommu_ops(device->dev); + + if (device == last_gdev) + break; + ops->remove_dev_pasid(device->dev, pasid); + } return ret; }
@@ -3423,10 +3434,8 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, }
ret = __iommu_set_group_pasid(domain, group, pasid); - if (ret) { - __iommu_remove_group_pasid(group, pasid); + if (ret) xa_erase(&group->pasid_array, pasid); - } out_unlock: mutex_unlock(&group->mutex); iommu_group_put(group);