PCI/P2PDMA: Warn if host bridge not in whitelist

If the host bridge is not in the whitelist print a warning in the
calc_map_type_and_dist_warn() path detailing the vendor and device IDs that
would need to be added to the whitelist.

Suggested-by: Don Dutile <ddutile@redhat.com>
Link: https://lore.kernel.org/r/20210610160609.28447-5-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index abcdb2a..c07c928 100644 (file)
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -309,7 +309,7 @@ static const struct pci_p2pdma_whitelist_entry {
 };
 
 static bool __host_bridge_whitelist(struct pci_host_bridge *host,
-                                   bool same_host_bridge)
+                                   bool same_host_bridge, bool warn)
 {
        struct pci_dev *root = pci_get_slot(host->bus, PCI_DEVFN(0, 0));
        const struct pci_p2pdma_whitelist_entry *entry;
@@ -331,6 +331,10 @@ static bool __host_bridge_whitelist(struct pci_host_bridge *host,
                return true;
        }
 
+       if (warn)
+               pci_warn(root, "Host bridge not in P2PDMA whitelist: %04x:%04x\n",
+                        vendor, device);
+
        return false;
 }
 
@@ -338,16 +342,17 @@ static bool __host_bridge_whitelist(struct pci_host_bridge *host,
  * 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 host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b)
+static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b,
+                                 bool warn)
 {
        struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus);
        struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus);
 
        if (host_a == host_b)
-               return __host_bridge_whitelist(host_a, true);
+               return __host_bridge_whitelist(host_a, true, warn);
 
-       if (__host_bridge_whitelist(host_a, false) &&
-           __host_bridge_whitelist(host_b, false))
+       if (__host_bridge_whitelist(host_a, false, warn) &&
+           __host_bridge_whitelist(host_b, false, warn))
                return true;
 
        return false;
@@ -485,7 +490,7 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
 
        if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) {
                if (!cpu_supports_p2pdma() &&
-                   !host_bridge_whitelist(provider, client))
+                   !host_bridge_whitelist(provider, client, acs_redirects))
                        map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
        }