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-rw-r--r--drivers/dma/ioat_dca.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/dma/ioat_dca.c b/drivers/dma/ioat_dca.c
index 6cf622da0286..78705ca7d36a 100644
--- a/drivers/dma/ioat_dca.c
+++ b/drivers/dma/ioat_dca.c
@@ -49,6 +49,23 @@
49 49
50#define DCA_TAG_MAP_MASK 0xDF 50#define DCA_TAG_MAP_MASK 0xDF
51 51
52/* expected tag map bytes for I/OAT ver.2 */
53#define DCA2_TAG_MAP_BYTE0 0x80
54#define DCA2_TAG_MAP_BYTE1 0x0
55#define DCA2_TAG_MAP_BYTE2 0x81
56#define DCA2_TAG_MAP_BYTE3 0x82
57#define DCA2_TAG_MAP_BYTE4 0x82
58
59/* verify if tag map matches expected values */
60static inline int dca2_tag_map_valid(u8 *tag_map)
61{
62 return ((tag_map[0] == DCA2_TAG_MAP_BYTE0) &&
63 (tag_map[1] == DCA2_TAG_MAP_BYTE1) &&
64 (tag_map[2] == DCA2_TAG_MAP_BYTE2) &&
65 (tag_map[3] == DCA2_TAG_MAP_BYTE3) &&
66 (tag_map[4] == DCA2_TAG_MAP_BYTE4));
67}
68
52/* 69/*
53 * "Legacy" DCA systems do not implement the DCA register set in the 70 * "Legacy" DCA systems do not implement the DCA register set in the
54 * I/OAT device. Software needs direct support for their tag mappings. 71 * I/OAT device. Software needs direct support for their tag mappings.
@@ -452,6 +469,13 @@ struct dca_provider *ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase)
452 ioatdca->tag_map[i] = 0; 469 ioatdca->tag_map[i] = 0;
453 } 470 }
454 471
472 if (!dca2_tag_map_valid(ioatdca->tag_map)) {
473 dev_err(&pdev->dev, "APICID_TAG_MAP set incorrectly by BIOS, "
474 "disabling DCA\n");
475 free_dca_provider(dca);
476 return NULL;
477 }
478
455 err = register_dca_provider(dca, &pdev->dev); 479 err = register_dca_provider(dca, &pdev->dev);
456 if (err) { 480 if (err) {
457 free_dca_provider(dca); 481 free_dca_provider(dca);