[PATCH] x86-64: robustify bad_dma_address handling

- set bad_dma_address explicitly to 0x0
- reserve 32 pages from bad_dma_address and up
- WARN_ON() a driver feeding us bad_dma_address

Thanks to Leo Duran <leo.duran@amd.com> for the suggestion.

Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Leo Duran <leo.duran@amd.com>
Cc: Job Mason <jdmason@kudzu.us>

1 files changed, 15 insertions, 2 deletions

diff --git a/arch/x86_64/kernel/pci-calgary.c b/arch/x86_64/kernel/pci-calgary.c
index 3d65b1d4c2b3..04480c3b68f5 100644
--- a/arch/x86_64/kernel/pci-calgary.c
+++ b/arch/x86_64/kernel/pci-calgary.c
@@ -138,6 +138,8 @@ static const unsigned long phb_debug_offsets[] = {
 
 #define PHB_DEBUG_STUFF_OFFSET  0x0020
 
+#define EMERGENCY_PAGES 32 /* = 128KB */
+
 unsigned int specified_table_size = TCE_TABLE_SIZE_UNSPECIFIED;
 static int translate_empty_slots __read_mostly = 0;
 static int calgary_detected __read_mostly = 0;
@@ -296,6 +298,16 @@ static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
 {
         unsigned long entry;
         unsigned long badbit;
+        unsigned long badend;
+
+        /* were we called with bad_dma_address? */
+        badend = bad_dma_address + (EMERGENCY_PAGES * PAGE_SIZE);
+        if (unlikely((dma_addr >= bad_dma_address) && (dma_addr < badend))) {
+                printk(KERN_ERR "Calgary: driver tried unmapping bad DMA "
+                       "address 0x%Lx\n", dma_addr);
+                WARN_ON(1);
+                return;
+        }
 
         entry = dma_addr >> PAGE_SHIFT;
 
@@ -656,8 +668,8 @@ static void __init calgary_reserve_regions(struct pci_dev *dev)
         u64 start;
         struct iommu_table *tbl = dev->sysdata;
 
-        /* reserve bad_dma_address in case it's a legal address */
-        iommu_range_reserve(tbl, bad_dma_address, 1);
+        /* reserve EMERGENCY_PAGES from bad_dma_address and up */
+        iommu_range_reserve(tbl, bad_dma_address, EMERGENCY_PAGES);
 
         /* avoid the BIOS/VGA first 640KB-1MB region */
         start = (640 * 1024);
@@ -1176,6 +1188,7 @@ int __init calgary_iommu_init(void)
         }
 
         force_iommu = 1;
+        bad_dma_address = 0x0;
         dma_ops = &calgary_dma_ops;
 
         return 0;