1 files changed, 56 insertions, 37 deletions

diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
index 4dcb671bd19f..f8d857453f8a 100644
--- a/arch/x86_64/kernel/pci-dma.c
+++ b/arch/x86_64/kernel/pci-dma.c
@@ -170,8 +170,20 @@ void dma_free_coherent(struct device *dev, size_t size,
 }
 EXPORT_SYMBOL(dma_free_coherent);
 
+static int forbid_dac __read_mostly;
+
 int dma_supported(struct device *dev, u64 mask)
 {
+#ifdef CONFIG_PCI
+        if (mask > 0xffffffff && forbid_dac > 0) {
+
+
+
+                printk(KERN_INFO "PCI: Disallowing DAC for device %s\n", dev->bus_id);
+                return 0;
+        }
+#endif
+
         if (dma_ops->dma_supported)
                 return dma_ops->dma_supported(dev, mask);
 
@@ -231,57 +243,64 @@ EXPORT_SYMBOL(dma_set_mask);
    allowed  overwrite iommu off workarounds for specific chipsets.
    soft  Use software bounce buffering (default for Intel machines)
    noaperture Don't touch the aperture for AGP.
+   allowdac Allow DMA >4GB
+   nodac    Forbid DMA >4GB
+   panic    Force panic when IOMMU overflows
 */
 __init int iommu_setup(char *p)
 {
-    iommu_merge = 1;
+        iommu_merge = 1;
 
         if (!p)
                 return -EINVAL;
 
-    while (*p) {
-            if (!strncmp(p,"off",3))
-                    no_iommu = 1;
-            /* gart_parse_options has more force support */
-            if (!strncmp(p,"force",5))
-                    force_iommu = 1;
-            if (!strncmp(p,"noforce",7)) {
-                    iommu_merge = 0;
-                    force_iommu = 0;
-            }
-
-            if (!strncmp(p, "biomerge",8)) {
-                    iommu_bio_merge = 4096;
-                    iommu_merge = 1;
-                    force_iommu = 1;
-            }
-            if (!strncmp(p, "panic",5))
-                    panic_on_overflow = 1;
-            if (!strncmp(p, "nopanic",7))
-                    panic_on_overflow = 0;
-            if (!strncmp(p, "merge",5)) {
-                    iommu_merge = 1;
-                    force_iommu = 1;
-            }
-            if (!strncmp(p, "nomerge",7))
-                    iommu_merge = 0;
-            if (!strncmp(p, "forcesac",8))
-                    iommu_sac_force = 1;
+        while (*p) {
+                if (!strncmp(p,"off",3))
+                        no_iommu = 1;
+                /* gart_parse_options has more force support */
+                if (!strncmp(p,"force",5))
+                        force_iommu = 1;
+                if (!strncmp(p,"noforce",7)) {
+                        iommu_merge = 0;
+                        force_iommu = 0;
+                }
+
+                if (!strncmp(p, "biomerge",8)) {
+                        iommu_bio_merge = 4096;
+                        iommu_merge = 1;
+                        force_iommu = 1;
+                }
+                if (!strncmp(p, "panic",5))
+                        panic_on_overflow = 1;
+                if (!strncmp(p, "nopanic",7))
+                        panic_on_overflow = 0;
+                if (!strncmp(p, "merge",5)) {
+                        iommu_merge = 1;
+                        force_iommu = 1;
+                }
+                if (!strncmp(p, "nomerge",7))
+                        iommu_merge = 0;
+                if (!strncmp(p, "forcesac",8))
+                        iommu_sac_force = 1;
+                if (!strncmp(p, "allowdac", 8))
+                        forbid_dac = 0;
+                if (!strncmp(p, "nodac", 5))
+                        forbid_dac = -1;
 
 #ifdef CONFIG_SWIOTLB
-            if (!strncmp(p, "soft",4))
-                    swiotlb = 1;
+                if (!strncmp(p, "soft",4))
+                        swiotlb = 1;
 #endif
 
 #ifdef CONFIG_IOMMU
-            gart_parse_options(p);
+                gart_parse_options(p);
 #endif
 
-            p += strcspn(p, ",");
-            if (*p == ',')
-                    ++p;
-    }
-    return 0;
+                p += strcspn(p, ",");
+                if (*p == ',')
+                        ++p;
+        }
+        return 0;
 }
 early_param("iommu", iommu_setup);