iommu/vt-d: Allocate domain info for real DMA sub-devices

Sub-devices of a real DMA device might exist on a separate segment than
the real DMA device and its IOMMU. These devices should still have a
valid device_domain_info, but the current dma alias model won't
allocate info for the subdevice.

This patch adds a segment member to struct device_domain_info and uses
the sub-device's BDF so that these sub-devices won't alias to other
devices.

Fixes: 2b0140c6 ("iommu/vt-d: Use pci_real_dma_dev() for mapping")
Cc: stable@vger.kernel.org # v5.6+
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20200527165617.297470-3-jonathan.derrick@intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu.c

@@ -2463,7 +2463,7 @@ dmar_search_domain_by_dev_info(int segment, int bus, int devfn)
 	struct device_domain_info *info;
 
 	list_for_each_entry(info, &device_domain_list, global)
-		if (info->iommu->segment == segment && info->bus == bus &&
+		if (info->segment == segment && info->bus == bus &&
 		    info->devfn == devfn)
 			return info;
 
@@ -2520,8 +2520,18 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 	if (!info)
 		return NULL;
 
+	if (!dev_is_real_dma_subdevice(dev)) {
 		info->bus = bus;
 		info->devfn = devfn;
+		info->segment = iommu->segment;
+	} else {
+		struct pci_dev *pdev = to_pci_dev(dev);
+
+		info->bus = pdev->bus->number;
+		info->devfn = pdev->devfn;
+		info->segment = pci_domain_nr(pdev->bus);
+	}
+
 	info->ats_supported = info->pasid_supported = info->pri_supported = 0;
 	info->ats_enabled = info->pasid_enabled = info->pri_enabled = 0;
 	info->ats_qdep = 0;
@@ -2561,7 +2571,8 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 
 	if (!found) {
 		struct device_domain_info *info2;
-		info2 = dmar_search_domain_by_dev_info(iommu->segment, bus, devfn);
+		info2 = dmar_search_domain_by_dev_info(info->segment, info->bus,
+						       info->devfn);
 		if (info2) {
 			found      = info2->domain;
 			info2->dev = dev;

include/linux/intel-iommu.h

@@ -609,6 +609,7 @@ struct device_domain_info {
 	struct list_head auxiliary_domains; /* auxiliary domains
 					     * attached to this device
 					     */
+	u32 segment;		/* PCI segment number */
 	u8 bus;			/* PCI bus number */
 	u8 devfn;		/* PCI devfn number */
 	u16 pfsid;		/* SRIOV physical function source ID */