[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>

diff --git a/arch/x86_64/kernel/pci-calgary.c b/arch/x86_64/kernel/pci-calgary.c
index 3d65b1d4c2b39e4110dc913159615089e4a5ab02..04480c3b68f5d15177192e8336fcdecda4f52b68 100644 (file)
--- 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;