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>

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 092330208869640a1e474abfd781bce41a5c6043..7422c76528458134f450eb496d52b1a297e18f8a 100644 (file)
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -924,6 +924,27 @@ static struct miscdevice  mei_misc_device = {
                .minor = MISC_DYNAMIC_MINOR,
 };
 
+/**
+ * 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
  *
@@ -939,6 +960,12 @@ 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;