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path: root/drivers/pci/p2pdma.c
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Diffstat (limited to 'drivers/pci/p2pdma.c')
-rw-r--r--drivers/pci/p2pdma.c38
1 files changed, 35 insertions, 3 deletions
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index c52298d76e64..742928d0053e 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -275,6 +275,30 @@ static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
}
/*
+ * If we can't find a common upstream bridge take a look at the root
+ * complex and compare it to a whitelist of known good hardware.
+ */
+static bool root_complex_whitelist(struct pci_dev *dev)
+{
+ struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
+ struct pci_dev *root = pci_get_slot(host->bus, PCI_DEVFN(0, 0));
+ unsigned short vendor, device;
+
+ if (!root)
+ return false;
+
+ vendor = root->vendor;
+ device = root->device;
+ pci_dev_put(root);
+
+ /* AMD ZEN host bridges can do peer to peer */
+ if (vendor == PCI_VENDOR_ID_AMD && device == 0x1450)
+ return true;
+
+ return false;
+}
+
+/*
* Find the distance through the nearest common upstream bridge between
* two PCI devices.
*
@@ -317,13 +341,13 @@ static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
* In this case, a list of all infringing bridge addresses will be
* populated in acs_list (assuming it's non-null) for printk purposes.
*/
-static int upstream_bridge_distance(struct pci_dev *a,
- struct pci_dev *b,
+static int upstream_bridge_distance(struct pci_dev *provider,
+ struct pci_dev *client,
struct seq_buf *acs_list)
{
+ struct pci_dev *a = provider, *b = client, *bb;
int dist_a = 0;
int dist_b = 0;
- struct pci_dev *bb = NULL;
int acs_cnt = 0;
/*
@@ -354,6 +378,14 @@ static int upstream_bridge_distance(struct pci_dev *a,
dist_a++;
}
+ /*
+ * Allow the connection if both devices are on a whitelisted root
+ * complex, but add an arbitary large value to the distance.
+ */
+ if (root_complex_whitelist(provider) &&
+ root_complex_whitelist(client))
+ return 0x1000 + dist_a + dist_b;
+
return -1;
check_b_path_acs: