[PATCH 06/13] iommu/amd: Use pci_find_dma_isolation_root() for IOMMU groups

[Alex Williamson]

The IVRS tables provides aliases, but not to the extent now provided
by PCI core with DMA alias support and pci_find_dma_isolation_root().
The expectation is that the kernel and IVRS will produce the same
result for topology based aliases while the kernel will also include
device specific DMA quirks.  We therefore drop the AMD-specific IOMMU
group discovery in favor of the common code.  This also allows us to
drop tracking of the IOMMU group on the alias dev_data structure.

Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
---
 drivers/iommu/amd_iommu.c       |  158 ++-------------------------------------
 drivers/iommu/amd_iommu_types.h |    1 
 2 files changed, 10 insertions(+), 149 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index c949520..3d58de4 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -46,7 +46,6 @@
 #include "amd_iommu_proto.h"
 #include "amd_iommu_types.h"
 #include "irq_remapping.h"
-#include "pci.h"
 
 #define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))
 
@@ -133,9 +132,6 @@ static void free_dev_data(struct iommu_dev_data *dev_data)
 	list_del(&dev_data->dev_data_list);
 	spin_unlock_irqrestore(&dev_data_list_lock, flags);
 
-	if (dev_data->group)
-		iommu_group_put(dev_data->group);
-
 	kfree(dev_data);
 }
 
@@ -264,107 +260,10 @@ static bool check_device(struct device *dev)
 	return true;
 }
 
-static struct pci_bus *find_hosted_bus(struct pci_bus *bus)
-{
-	while (!bus->self) {
-		if (!pci_is_root_bus(bus))
-			bus = bus->parent;
-		else
-			return ERR_PTR(-ENODEV);
-	}
-
-	return bus;
-}
-
-#define REQ_ACS_FLAGS	(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
-
-static struct pci_dev *get_isolation_root(struct pci_dev *pdev)
-{
-	struct pci_dev *dma_pdev = pdev;
-
-	/* Account for quirked devices */
-	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
-
-	/*
-	 * If it's a multifunction device that does not support our
-	 * required ACS flags, add to the same group as lowest numbered
-	 * function that also does not suport the required ACS flags.
-	 */
-	if (dma_pdev->multifunction &&
-	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS)) {
-		u8 i, slot = PCI_SLOT(dma_pdev->devfn);
-
-		for (i = 0; i < 8; i++) {
-			struct pci_dev *tmp;
-
-			tmp = pci_get_slot(dma_pdev->bus, PCI_DEVFN(slot, i));
-			if (!tmp)
-				continue;
-
-			if (!pci_acs_enabled(tmp, REQ_ACS_FLAGS)) {
-				swap_pci_ref(&dma_pdev, tmp);
-				break;
-			}
-			pci_dev_put(tmp);
-		}
-	}
-
-	/*
-	 * Devices on the root bus go through the iommu.  If that's not us,
-	 * find the next upstream device and test ACS up to the root bus.
-	 * Finding the next device may require skipping virtual buses.
-	 */
-	while (!pci_is_root_bus(dma_pdev->bus)) {
-		struct pci_bus *bus = find_hosted_bus(dma_pdev->bus);
-		if (IS_ERR(bus))
-			break;
-
-		if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
-			break;
-
-		swap_pci_ref(&dma_pdev, pci_dev_get(bus->self));
-	}
-
-	return dma_pdev;
-}
-
-static int use_pdev_iommu_group(struct pci_dev *pdev, struct device *dev)
-{
-	struct iommu_group *group = iommu_group_get(&pdev->dev);
-	int ret;
-
-	if (!group) {
-		group = iommu_group_alloc();
-		if (IS_ERR(group))
-			return PTR_ERR(group);
-
-		WARN_ON(&pdev->dev != dev);
-	}
-
-	ret = iommu_group_add_device(group, dev);
-	iommu_group_put(group);
-	return ret;
-}
-
-static int use_dev_data_iommu_group(struct iommu_dev_data *dev_data,
-				    struct device *dev)
-{
-	if (!dev_data->group) {
-		struct iommu_group *group = iommu_group_alloc();
-		if (IS_ERR(group))
-			return PTR_ERR(group);
-
-		dev_data->group = group;
-	}
-
-	return iommu_group_add_device(dev_data->group, dev);
-}
-
 static int init_iommu_group(struct device *dev)
 {
-	struct iommu_dev_data *dev_data;
 	struct iommu_group *group;
-	struct pci_dev *dma_pdev;
+	struct pci_dev *pdev;
 	int ret;
 
 	group = iommu_group_get(dev);
@@ -373,58 +272,21 @@ static int init_iommu_group(struct device *dev)
 		return 0;
 	}
 
-	dev_data = find_dev_data(get_device_id(dev));
-	if (!dev_data)
-		return -ENOMEM;
-
-	if (dev_data->alias_data) {
-		u16 alias;
-		struct pci_bus *bus;
+	pdev = pci_find_dma_isolation_root(to_pci_dev(dev));
 
-		if (dev_data->alias_data->group)
-			goto use_group;
-
-		/*
-		 * If the alias device exists, it's effectively just a first
-		 * level quirk for finding the DMA source.
-		 */
-		alias = amd_iommu_alias_table[dev_data->devid];
-		dma_pdev = pci_get_bus_and_slot(alias >> 8, alias & 0xff);
-		if (dma_pdev) {
-			dma_pdev = get_isolation_root(dma_pdev);
-			goto use_pdev;
-		}
-
-		/*
-		 * If the alias is virtual, try to find a parent device
-		 * and test whether the IOMMU group is actualy rooted above
-		 * the alias.  Be careful to also test the parent device if
-		 * we think the alias is the root of the group.
-		 */
-		bus = pci_find_bus(0, alias >> 8);
-		if (!bus)
-			goto use_group;
+	group = iommu_group_get(&pdev->dev);
 
-		bus = find_hosted_bus(bus);
-		if (IS_ERR(bus) || !bus->self)
-			goto use_group;
+	if (!group) {
+		group = iommu_group_alloc();
+		if (IS_ERR(group))
+			return PTR_ERR(group);
+	}
 
-		dma_pdev = get_isolation_root(pci_dev_get(bus->self));
-		if (dma_pdev != bus->self || (dma_pdev->multifunction &&
-		    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS)))
-			goto use_pdev;
+	ret = iommu_group_add_device(group, dev);
 
-		pci_dev_put(dma_pdev);
-		goto use_group;
-	}
+	iommu_group_put(group);
 
-	dma_pdev = get_isolation_root(pci_dev_get(to_pci_dev(dev)));
-use_pdev:
-	ret = use_pdev_iommu_group(dma_pdev, dev);
-	pci_dev_put(dma_pdev);
 	return ret;
-use_group:
-	return use_dev_data_iommu_group(dev_data->alias_data, dev);
 }
 
 static int iommu_init_device(struct device *dev)
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index f1a5abf..7277a20 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -432,7 +432,6 @@ struct iommu_dev_data {
 	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 */

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