iommu/amd: Properly account for virtual aliases in IOMMU groups

An alias doesn't always point to a physical device.  When this
happens we must first verify that the IOMMU group isn't rooted in
a device above the alias.  In this case the alias is effectively
just another quirk for the devices aliased to it.  Alternatively,
the virtual alias itself may be the root of the IOMMU group.  To
support this, allow a group to be hosted on the alias dev_data
for use by anything that might have the same alias.

Signed-off-by: Alex williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index c9aa3d0..e38ab43 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -426,6 +426,7 @@
 	struct iommu_dev_data *alias_data;/* The alias dev_data */
 	struct protection_domain *domain; /* Domain the device is bound to */
 	atomic_t bind;			  /* Domain attach reference count */
+	struct iommu_group *group;	  /* IOMMU group for virtual aliases */
 	u16 devid;			  /* PCI Device ID */
 	bool iommu_v2;			  /* Device can make use of IOMMUv2 */
 	bool passthrough;		  /* Default for device is pt_domain */