intel-iommu: Restore DMAR_BROKEN_GFX_WA option for broken graphics drivers

We need to give people a little more time to fix the broken drivers.
Re-introduce this, but tied in properly with the 'iommu=pt' support this
time. Change the config option name and make it default to 'no' too.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 31 insertions, 10 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c07f72205909..738bdc6b0f8b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1913,6 +1913,18 @@ config DMAR_DEFAULT_ON
           recommended you say N here while the DMAR code remains
           experimental.
 
+config DMAR_BROKEN_GFX_WA
+        def_bool n
+        prompt "Workaround broken graphics drivers (going away soon)"
+        depends on DMAR
+        ---help---
+          Current Graphics drivers tend to use physical address
+          for DMA and avoid using DMA APIs. Setting this config
+          option permits the IOMMU driver to set a unity map for
+          all the OS-visible memory. Hence the driver can continue
+          to use physical addresses for DMA, at least until this
+          option is removed in the 2.6.32 kernel.
+
 config DMAR_FLOPPY_WA
         def_bool y
         depends on DMAR
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index ae5ccdf8b19f..5ee8305257ea 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -2127,16 +2127,18 @@ static int iommu_prepare_static_identity_mapping(void)
                 return -EFAULT;
 
         for_each_pci_dev(pdev) {
-                printk(KERN_INFO "IOMMU: identity mapping for device %s\n",
-                       pci_name(pdev));
+                if (iommu_identity_mapping == 1 || IS_GFX_DEVICE(pdev)) {
+                        printk(KERN_INFO "IOMMU: identity mapping for device %s\n",
+                               pci_name(pdev));
 
-                ret = domain_context_mapping(si_domain, pdev,
-                                             CONTEXT_TT_MULTI_LEVEL);
-                if (ret)
-                        return ret;
-                ret = domain_add_dev_info(si_domain, pdev);
-                if (ret)
-                        return ret;
+                        ret = domain_context_mapping(si_domain, pdev,
+                                                     CONTEXT_TT_MULTI_LEVEL);
+                        if (ret)
+                                return ret;
+                        ret = domain_add_dev_info(si_domain, pdev);
+                        if (ret)
+                                return ret;
+                }
         }
 
         return 0;
@@ -2291,6 +2293,10 @@ int __init init_dmars(void)
          * identity mapping if iommu_identity_mapping is set.
          */
         if (!iommu_pass_through) {
+#ifdef CONFIG_DMAR_BROKEN_GFX_WA
+                if (!iommu_identity_mapping)
+                        iommu_identity_mapping = 2;
+#endif
                 if (iommu_identity_mapping)
                         iommu_prepare_static_identity_mapping();
                 /*
@@ -2444,7 +2450,10 @@ static int iommu_dummy(struct pci_dev *pdev)
 
 static int iommu_should_identity_map(struct pci_dev *pdev)
 {
-        return pdev->dma_mask > DMA_BIT_MASK(32);
+        if (iommu_identity_mapping == 2)
+                return IS_GFX_DEVICE(pdev);
+        else
+                return pdev->dma_mask > DMA_BIT_MASK(32);
 }
 
 /* Check if the pdev needs to go through non-identity map and unmap process.*/