iommu/vt-d: Remove VMD child device sanity check

Remove the sanity check required for VMD child devices.  The new
pci_real_dma_dev() DMA alias mechanism places them in the same IOMMU group
as the VMD endpoint.  Assignment of the group would require assigning the
VMD endpoint, where unbinding the VMD endpoint removes the child device
domain from the hierarchy.

Link: https://lore.kernel.org/r/1579613871-301529-6-git-send-email-jonathan.derrick@intel.comSigned-off-by: NJon Derrick <jonathan.derrick@intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NLu Baolu <baolu.lu@linux.intel.com>

drivers/iommu/intel-iommu.c

@@ -774,15 +774,7 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
 	if (dev_is_pci(dev)) {
 		struct pci_dev *pf_pdev;
 
-		pdev = to_pci_dev(dev);
-
-#ifdef CONFIG_X86
-		/* VMD child devices currently cannot be handled individually */
-		if (is_vmd(pdev->bus))
-			return NULL;
-#endif
-
-		pdev = pci_real_dma_dev(pdev);
+		pdev = pci_real_dma_dev(to_pci_dev(dev));
 
 		/* VFs aren't listed in scope tables; we need to look up
 		 * the PF instead to find the IOMMU. */