linux-kernel - [PATCH v1 4/6] PCI/P2PDMA: Print a warning if the host bridge is not in the whitelist

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Message-Id: <20210610160609.28447-5-logang@deltatee.com>
Date:   Thu, 10 Jun 2021 10:06:07 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        Bjorn Helgaas <helgaas@...nel.org>
Cc:     Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian König <christian.koenig@....com>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v1 4/6] PCI/P2PDMA: Print a warning if the host bridge is not in the 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@...hat.com>
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 drivers/pci/p2pdma.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 09c864f193d2..2de4a9e2da58 100644
--- 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;
@@ -483,7 +488,7 @@ 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;
 	}
 
-- 
2.20.1