mei: add mei_quirk_probe function

The main purpose of this function is to exclude ME devices
without support for MEI/HECI interface from binding

Currently affected systems are C600/X79 based servers
that expose PCI device even though it doesn't supported ME Interface.
MEI driver accessing such nonfunctional device can corrupt
the system.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index b0903bd44bf7..86b73e596263 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -906,6 +906,27 @@ static struct miscdevice  mei_misc_device = {
 };
 
 /**
+ * mei_quirk_probe - probe for devices that doesn't valid ME interface
+ * @pdev: PCI device structure
+ * @ent: entry into pci_device_table
+ *
+ * returns true if ME Interface is valid, false otherwise
+ */
+static bool __devinit mei_quirk_probe(struct pci_dev *pdev,
+                                const struct pci_device_id *ent)
+{
+        u32 reg;
+        if (ent->device == MEI_DEV_ID_PBG_1) {
+                pci_read_config_dword(pdev, 0x48, &reg);
+                /* make sure that bit 9 is up and bit 10 is down */
+                if ((reg & 0x600) == 0x200) {
+                        dev_info(&pdev->dev, "Device doesn't have valid ME Interface\n");
+                        return false;
+                }
+        }
+        return true;
+}
+/**
  * mei_probe - Device Initialization Routine
  *
  * @pdev: PCI device structure
@@ -920,6 +941,12 @@ static int __devinit mei_probe(struct pci_dev *pdev,
         int err;
 
         mutex_lock(&mei_mutex);
+
+        if (!mei_quirk_probe(pdev, ent)) {
+                err = -ENODEV;
+                goto end;
+        }
+
         if (mei_device) {
                 err = -EEXIST;
                 goto end;