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Diffstat (limited to 'arch/powerpc/kernel/iommu.c')
-rw-r--r--arch/powerpc/kernel/iommu.c35
1 files changed, 34 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 95edad4faf2..c08ceca6277 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -47,6 +47,8 @@ static int novmerge = 0;
static int novmerge = 1;
#endif
+static int protect4gb = 1;
+
static inline unsigned long iommu_num_pages(unsigned long vaddr,
unsigned long slen)
{
@@ -58,6 +60,16 @@ static inline unsigned long iommu_num_pages(unsigned long vaddr,
return npages;
}
+static int __init setup_protect4gb(char *str)
+{
+ if (strcmp(str, "on") == 0)
+ protect4gb = 1;
+ else if (strcmp(str, "off") == 0)
+ protect4gb = 0;
+
+ return 1;
+}
+
static int __init setup_iommu(char *str)
{
if (!strcmp(str, "novmerge"))
@@ -67,6 +79,7 @@ static int __init setup_iommu(char *str)
return 1;
}
+__setup("protect4gb=", setup_protect4gb);
__setup("iommu=", setup_iommu);
static unsigned long iommu_range_alloc(struct iommu_table *tbl,
@@ -429,6 +442,9 @@ void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
{
unsigned long sz;
+ unsigned long start_index, end_index;
+ unsigned long entries_per_4g;
+ unsigned long index;
static int welcomed = 0;
struct page *page;
@@ -450,7 +466,7 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
#ifdef CONFIG_CRASH_DUMP
if (ppc_md.tce_get) {
- unsigned long index, tceval;
+ unsigned long tceval;
unsigned long tcecount = 0;
/*
@@ -480,6 +496,23 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
ppc_md.tce_free(tbl, tbl->it_offset, tbl->it_size);
#endif
+ /*
+ * DMA cannot cross 4 GB boundary. Mark last entry of each 4
+ * GB chunk as reserved.
+ */
+ if (protect4gb) {
+ entries_per_4g = 0x100000000l >> IOMMU_PAGE_SHIFT;
+
+ /* Mark the last bit before a 4GB boundary as used */
+ start_index = tbl->it_offset | (entries_per_4g - 1);
+ start_index -= tbl->it_offset;
+
+ end_index = tbl->it_size;
+
+ for (index = start_index; index < end_index - 1; index += entries_per_4g)
+ __set_bit(index, tbl->it_map);
+ }
+
if (!welcomed) {
printk(KERN_INFO "IOMMU table initialized, virtual merging %s\n",
novmerge ? "disabled" : "enabled");