Commit b3f6fcd8 authored by Tushar Dave's avatar Tushar Dave Committed by Joerg Roedel
Browse files

iommu: Skip PASID validation for devices without PASID capability 



Generally PASID support requires ACS settings that usually create
single device groups, but there are some niche cases where we can get
multi-device groups and still have working PASID support. The primary
issue is that PCI switches are not required to treat PASID tagged TLPs
specially so appropriate ACS settings are required to route all TLPs to
the host bridge if PASID is going to work properly.

pci_enable_pasid() does check that each device that will use PASID has
the proper ACS settings to achieve this routing.

However, no-PASID devices can be combined with PASID capable devices
within the same topology using non-uniform ACS settings. In this case
the no-PASID devices may not have strict route to host ACS flags and
end up being grouped with the PASID devices.

This configuration fails to allow use of the PASID within the iommu
core code which wrongly checks if the no-PASID device supports PASID.

Fix this by ignoring no-PASID devices during the PASID validation. They
will never issue a PASID TLP anyhow so they can be ignored.

Fixes: c404f55c ("iommu: Validate the PASID in iommu_attach_device_pasid()")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarTushar Dave <tdave@nvidia.com>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarVasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20250520011937.3230557-1-tdave@nvidia.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 82f2b0b9

drivers/iommu/iommu.c

+28 −15
Original line number Diff line number Diff line
@@ -3366,11 +3366,13 @@ static int __iommu_set_group_pasid(struct iommu_domain *domain, 
	int ret;



	for_each_group_device(group, device) {

		if (device->dev->iommu->max_pasids > 0) {

			ret = domain->ops->set_dev_pasid(domain, device->dev,

							 pasid, old);

			if (ret)

				goto err_revert;

		}

	}



	return 0;
@@ -3379,16 +3381,19 @@ static int __iommu_set_group_pasid(struct iommu_domain *domain, 
	for_each_group_device(group, device) {

		if (device == last_gdev)

			break;

		if (device->dev->iommu->max_pasids > 0) {

			/*

			 * If no old domain, undo the succeeded devices/pasid.

		 * Otherwise, rollback the succeeded devices/pasid to the old

		 * domain. And it is a driver bug to fail attaching with a

		 * previously good domain.

			 * Otherwise, rollback the succeeded devices/pasid to

			 * the old domain. And it is a driver bug to fail

			 * attaching with a previously good domain.

			 */

		if (!old || WARN_ON(old->ops->set_dev_pasid(old, device->dev,

			if (!old ||

			    WARN_ON(old->ops->set_dev_pasid(old, device->dev,

							    pasid, domain)))

				iommu_remove_dev_pasid(device->dev, pasid, domain);

		}

	}

	return ret;

}
@@ -3398,9 +3403,11 @@ static void __iommu_remove_group_pasid(struct iommu_group *group, 
{

	struct group_device *device;



	for_each_group_device(group, device)

	for_each_group_device(group, device) {

		if (device->dev->iommu->max_pasids > 0)

			iommu_remove_dev_pasid(device->dev, pasid, domain);

	}

}



/*

 * iommu_attach_device_pasid() - Attach a domain to pasid of device
@@ -3440,7 +3447,13 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, 


	mutex_lock(&group->mutex);

	for_each_group_device(group, device) {

		if (pasid >= device->dev->iommu->max_pasids) {

		/*

		 * Skip PASID validation for devices without PASID support

		 * (max_pasids = 0). These devices cannot issue transactions

		 * with PASID, so they don't affect group's PASID usage.

		 */

		if ((device->dev->iommu->max_pasids > 0) &&

		    (pasid >= device->dev->iommu->max_pasids)) {

			ret = -EINVAL;

			goto out_unlock;

		}