From c34a750e0028c7a726e008524d8ac16b379f9c8d Mon Sep 17 00:00:00 2001 From: Tushar Dave Date: Mon, 19 May 2025 18:19:37 -0700 Subject: [PATCH] iommu: Skip PASID validation for devices without PASID capability BugLink: https://bugs.launchpad.net/bugs/2119656 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: c404f55c26fc ("iommu: Validate the PASID in iommu_attach_device_pasid()") Cc: stable@vger.kernel.org Signed-off-by: Tushar Dave Reviewed-by: Lu Baolu Reviewed-by: Vasant Hegde Link: https://lore.kernel.org/r/20250520011937.3230557-1-tdave@nvidia.com Signed-off-by: Joerg Roedel (cherry picked from commit b3f6fcd8404f9f92262303369bb877ec5d188a81) Signed-off-by: Nirmoy Das Acked-by: Carol L Soto Acked-by: Matt Ochs Acked-by: Noah Wager Acked-by: Jacob Martin Signed-off-by: Brad Figg --- drivers/iommu/iommu.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 0ad55649e2d00..62e1d63725031 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3341,9 +3341,11 @@ static int __iommu_set_group_pasid(struct iommu_domain *domain, int ret; for_each_group_device(group, device) { - ret = domain->ops->set_dev_pasid(domain, device->dev, pasid); - if (ret) - goto err_revert; + if (device->dev->iommu->max_pasids > 0) { + ret = domain->ops->set_dev_pasid(domain, device->dev, pasid); + if (ret) + goto err_revert; + } } return 0; @@ -3355,7 +3357,8 @@ static int __iommu_set_group_pasid(struct iommu_domain *domain, if (device == last_gdev) break; - ops->remove_dev_pasid(device->dev, pasid, domain); + if (device->dev->iommu->max_pasids > 0) + ops->remove_dev_pasid(device->dev, pasid, domain); } return ret; } @@ -3368,8 +3371,10 @@ static void __iommu_remove_group_pasid(struct iommu_group *group, const struct iommu_ops *ops; for_each_group_device(group, device) { - ops = dev_iommu_ops(device->dev); - ops->remove_dev_pasid(device->dev, pasid, domain); + if (device->dev->iommu->max_pasids > 0) { + ops = dev_iommu_ops(device->dev); + ops->remove_dev_pasid(device->dev, pasid, domain); + } } } @@ -3403,7 +3408,13 @@ 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; }