iommufd: Enforce PASID-compatible domain for RID

JIRA: https://issues.redhat.com/browse/RHEL-114131
Upstream-Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit 4c3f4f4
Author: Yi Liu <yi.l.liu@intel.com>
Date: Fri Mar 21 10:19:34 2025 -0700

    iommufd: Enforce PASID-compatible domain for RID

    Per the definition of IOMMU_HWPT_ALLOC_PASID, iommufd needs to enforce
    the RID to use PASID-compatible domain if PASID has been attached, and
    vice versa. The PASID path has already enforced it. This adds the
    enforcement in the RID path.

    This enforcement requires a lock across the RID and PASID attach path,
    the idev->igroup->lock is used as both the RID and the PASID path holds
    it.

    Link: https://patch.msgid.link/r/20250321171940.7213-13-yi.l.liu@intel.com
    Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
    Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
    Signed-off-by: Yi Liu <yi.l.liu@intel.com>
    Tested-by: Nicolin Chen <nicolinc@nvidia.com>
    Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

(cherry picked from commit 4c3f4f4)
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>

Author: snits

drivers/iommu/iommufd/device.c

@@ -399,8 +399,28 @@ static int iommufd_hwpt_pasid_compat(struct iommufd_hw_pagetable *hwpt,
 				     struct iommufd_device *idev,
 				     ioasid_t pasid)
 {
-	if (pasid != IOMMU_NO_PASID && !hwpt->pasid_compat)
-		return -EINVAL;
+	struct iommufd_group *igroup = idev->igroup;
+
+	lockdep_assert_held(&igroup->lock);
+
+	if (pasid == IOMMU_NO_PASID) {
+		unsigned long start = IOMMU_NO_PASID;
+
+		if (!hwpt->pasid_compat &&
+		    xa_find_after(&igroup->pasid_attach,
+				  &start, UINT_MAX, XA_PRESENT))
+			return -EINVAL;
+	} else {
+		struct iommufd_attach *attach;
+
+		if (!hwpt->pasid_compat)
+			return -EINVAL;
+
+		attach = xa_load(&igroup->pasid_attach, IOMMU_NO_PASID);
+		if (attach && attach->hwpt && !attach->hwpt->pasid_compat)
+			return -EINVAL;
+	}
+
 	return 0;
 }
 
@@ -411,8 +431,6 @@ static int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
 	struct iommufd_attach_handle *handle;
 	int rc;
 
-	lockdep_assert_held(&idev->igroup->lock);
-
 	rc = iommufd_hwpt_pasid_compat(hwpt, idev, pasid);
 	if (rc)
 		return rc;