1 files changed, 26 insertions, 6 deletions

diff --git a/drivers/dma/ioat/dca.c b/drivers/dma/ioat/dca.c
index abd9038e06b1..9b041858d10d 100644
--- a/drivers/dma/ioat/dca.c
+++ b/drivers/dma/ioat/dca.c
@@ -242,8 +242,7 @@ static struct dca_ops ioat_dca_ops = {
 };
 
 
-struct dca_provider * __devinit
-ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
+struct dca_provider *ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 {
         struct dca_provider *dca;
         struct ioat_dca_priv *ioatdca;
@@ -408,8 +407,7 @@ static int ioat2_dca_count_dca_slots(void __iomem *iobase, u16 dca_offset)
         return slots;
 }
 
-struct dca_provider * __devinit
-ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase)
+struct dca_provider *ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 {
         struct dca_provider *dca;
         struct ioat_dca_priv *ioatdca;
@@ -604,8 +602,24 @@ static int ioat3_dca_count_dca_slots(void *iobase, u16 dca_offset)
         return slots;
 }
 
-struct dca_provider * __devinit
-ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase)
+static inline int dca3_tag_map_invalid(u8 *tag_map)
+{
+        /*
+         * If the tag map is not programmed by the BIOS the default is:
+         * 0x80 0x80 0x80 0x80 0x80 0x00 0x00 0x00
+         *
+         * This an invalid map and will result in only 2 possible tags
+         * 0x1F and 0x00.  0x00 is an invalid DCA tag so we know that
+         * this entire definition is invalid.
+         */
+        return ((tag_map[0] == DCA_TAG_MAP_VALID) &&
+                (tag_map[1] == DCA_TAG_MAP_VALID) &&
+                (tag_map[2] == DCA_TAG_MAP_VALID) &&
+                (tag_map[3] == DCA_TAG_MAP_VALID) &&
+                (tag_map[4] == DCA_TAG_MAP_VALID));
+}
+
+struct dca_provider *ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase)
 {
         struct dca_provider *dca;
         struct ioat_dca_priv *ioatdca;
@@ -674,6 +688,12 @@ ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase)
                 ioatdca->tag_map[i] = bit & DCA_TAG_MAP_MASK;
         }
 
+        if (dca3_tag_map_invalid(ioatdca->tag_map)) {
+                dev_err(&pdev->dev, "APICID_TAG_MAP set incorrectly by BIOS, disabling DCA\n");
+                free_dca_provider(dca);
+                return NULL;
+        }
+
         err = register_dca_provider(dca, &pdev->dev);
         if (err) {
                 free_dca_provider(dca);