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path: root/drivers/dma/ioat/dca.c
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Diffstat (limited to 'drivers/dma/ioat/dca.c')
-rw-r--r--drivers/dma/ioat/dca.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/dma/ioat/dca.c b/drivers/dma/ioat/dca.c
index abd9038e06b1..d6668071bd0d 100644
--- a/drivers/dma/ioat/dca.c
+++ b/drivers/dma/ioat/dca.c
@@ -604,6 +604,23 @@ static int ioat3_dca_count_dca_slots(void *iobase, u16 dca_offset)
return slots;
}
+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 * __devinit
ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase)
{
@@ -674,6 +691,12 @@ 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);