PCI: Use function 0 VPD for identical functions, regular VPD for others

932c435caba8 ("PCI: Add dev_flags bit to access VPD through function 0")
added PCI_DEV_FLAGS_VPD_REF_F0.  Previously, we set the flag on every
non-zero function of quirked devices.  If a function turned out to be
different from function 0, i.e., it had a different class, vendor ID, or
device ID, the flag remained set but we didn't make VPD accessible at all.

Flip this around so we only set PCI_DEV_FLAGS_VPD_REF_F0 for functions that
are identical to function 0, and allow regular VPD access for any other
functions.

[bhelgaas: changelog, stable tag]
Fixes: 932c435caba8 ("PCI: Add dev_flags bit to access VPD through function 0")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Acked-by: Myron Stowe <myron.stowe@redhat.com>
Acked-by: Mark Rustad <mark.d.rustad@intel.com>
CC: stable@vger.kernel.org

2 files changed, 18 insertions, 24 deletions

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 5a5f0a7ba801..59ac36fe7c42 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -475,23 +475,6 @@ static const struct pci_vpd_ops pci_vpd_f0_ops = {
         .release = pci_vpd_pci22_release,
 };
 
-static int pci_vpd_f0_dev_check(struct pci_dev *dev)
-{
-        struct pci_dev *tdev = pci_get_slot(dev->bus,
-                                            PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
-        int ret = 0;
-
-        if (!tdev)
-                return -ENODEV;
-        if (!tdev->vpd || !tdev->multifunction ||
-            dev->class != tdev->class || dev->vendor != tdev->vendor ||
-            dev->device != tdev->device)
-                ret = -ENODEV;
-
-        pci_dev_put(tdev);
-        return ret;
-}
-
 int pci_vpd_pci22_init(struct pci_dev *dev)
 {
         struct pci_vpd_pci22 *vpd;
@@ -500,12 +483,7 @@ int pci_vpd_pci22_init(struct pci_dev *dev)
         cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
         if (!cap)
                 return -ENODEV;
-        if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0) {
-                int ret = pci_vpd_f0_dev_check(dev);
 
-                if (ret)
-                        return ret;
-        }
         vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
         if (!vpd)
                 return -ENOMEM;
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 6a30252cd79f..b03373fd05ca 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -1907,11 +1907,27 @@ static void quirk_netmos(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_VENDOR_ID_NETMOS, PCI_ANY_ID,
                          PCI_CLASS_COMMUNICATION_SERIAL, 8, quirk_netmos);
 
+/*
+ * Quirk non-zero PCI functions to route VPD access through function 0 for
+ * devices that share VPD resources between functions.  The functions are
+ * expected to be identical devices.
+ */
 static void quirk_f0_vpd_link(struct pci_dev *dev)
 {
-        if (!dev->multifunction || !PCI_FUNC(dev->devfn))
+        struct pci_dev *f0;
+
+        if (!PCI_FUNC(dev->devfn))
                 return;
-        dev->dev_flags |= PCI_DEV_FLAGS_VPD_REF_F0;
+
+        f0 = pci_get_slot(dev->bus, PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
+        if (!f0)
+                return;
+
+        if (f0->vpd && dev->class == f0->class &&
+            dev->vendor == f0->vendor && dev->device == f0->device)
+                dev->dev_flags |= PCI_DEV_FLAGS_VPD_REF_F0;
+
+        pci_dev_put(f0);
 }
 DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
                               PCI_CLASS_NETWORK_ETHERNET, 8, quirk_f0_vpd_link);