2 files changed, 102 insertions, 0 deletions

diff --git a/arch/x86/include/asm/iommu_table.h b/arch/x86/include/asm/iommu_table.h
new file mode 100644
index 000000000000..435176f96a56
--- /dev/null
+++ b/arch/x86/include/asm/iommu_table.h
@@ -0,0 +1,95 @@
+
+#ifndef _ASM_X86_IOMMU_TABLE_H
+#define _ASM_X86_IOMMU_TABLE_H
+
+#include <asm/swiotlb.h>
+
+/*
+ * History lesson:
+ * The execution chain of IOMMUs in 2.6.36 looks as so:
+ *
+ *            [xen-swiotlb]
+ *                 |
+ *         +----[swiotlb *]--+
+ *        /         |         \
+ *       /          |          \
+ *    [GART]     [Calgary]  [Intel VT-d]
+ *     /
+ *    /
+ * [AMD-Vi]
+ *
+ * *: if SWIOTLB detected 'iommu=soft'/'swiotlb=force' it would skip
+ * over the rest of IOMMUs and unconditionally initialize the SWIOTLB.
+ * Also it would surreptitiously initialize set the swiotlb=1 if there were
+ * more than 4GB and if the user did not pass in 'iommu=off'. The swiotlb
+ * flag would be turned off by all IOMMUs except the Calgary one.
+ *
+ * The IOMMU_INIT* macros allow a similar tree (or more complex if desired)
+ * to be built by defining who we depend on.
+ *
+ * And all that needs to be done is to use one of the macros in the IOMMU
+ * and the pci-dma.c will take care of the rest.
+ */
+
+struct iommu_table_entry {
+        initcall_t      detect;
+        initcall_t      depend;
+        void            (*early_init)(void); /* No memory allocate available. */
+        void            (*late_init)(void); /* Yes, can allocate memory. */
+#define IOMMU_FINISH_IF_DETECTED (1<<0)
+#define IOMMU_DETECTED           (1<<1)
+        int             flags;
+};
+/*
+ * Macro fills out an entry in the .iommu_table that is equivalent
+ * to the fields that 'struct iommu_table_entry' has. The entries
+ * that are put in the .iommu_table section are not put in any order
+ * hence during boot-time we will have to resort them based on
+ * dependency. */
+
+
+#define __IOMMU_INIT(_detect, _depend, _early_init, _late_init, _finish)\
+        static const struct iommu_table_entry const                     \
+                __iommu_entry_##_detect __used                          \
+        __attribute__ ((unused, __section__(".iommu_table"),            \
+                        aligned((sizeof(void *)))))     \
+        = {_detect, _depend, _early_init, _late_init,                   \
+           _finish ? IOMMU_FINISH_IF_DETECTED : 0}
+/*
+ * The simplest IOMMU definition. Provide the detection routine
+ * and it will be run after the SWIOTLB and the other IOMMUs
+ * that utilize this macro. If the IOMMU is detected (ie, the
+ * detect routine returns a positive value), the other IOMMUs
+ * are also checked. You can use IOMMU_INIT_FINISH if you prefer
+ * to stop detecting the other IOMMUs after yours has been detected.
+ */
+#define IOMMU_INIT_POST(_detect)                                        \
+        __IOMMU_INIT(_detect, pci_swiotlb_detect,  0, 0, 0)
+
+#define IOMMU_INIT_POST_FINISH(detect)                                  \
+        __IOMMU_INIT(_detect, pci_swiotlb_detect,  0, 0, 1)
+
+/*
+ * A more sophisticated version of IOMMU_INIT. This variant requires:
+ *  a). A detection routine function.
+ *  b). The name of the detection routine we depend on to get called
+ *      before us.
+ *  c). The init routine which gets called if the detection routine
+ *      returns a positive value from the pci_iommu_alloc. This means
+ *      no presence of a memory allocator.
+ *  d). Similar to the 'init', except that this gets called from pci_iommu_init
+ *      where we do have a memory allocator.
+ *
+ * The _CONT vs the _EXIT differs in that the _CONT variant will
+ * continue detecting other IOMMUs in the call list after the
+ * the detection routine returns a positive number. The _EXIT will
+ * stop the execution chain. Both will still call the 'init' and
+ * 'late_init' functions if they are set.
+ */
+#define IOMMU_INIT_FINISH(_detect, _depend, _init, _late_init)          \
+        __IOMMU_INIT(_detect, _depend, _init, _late_init, 1)
+
+#define IOMMU_INIT(_detect, _depend, _init, _late_init)                 \
+        __IOMMU_INIT(_detect, _depend, _init, _late_init, 0)
+
+#endif /* _ASM_X86_IOMMU_TABLE_H */
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index d0bb52296fa3..b92e040466c1 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -260,6 +260,13 @@ SECTIONS
                 *(.altinstr_replacement)
         }
 
+        .iommu_table : AT(ADDR(.iommu_table) - LOAD_OFFSET) {
+                __iommu_table = .;
+                *(.iommu_table)
+                . = ALIGN(8);
+                __iommu_table_end = .;
+        }
+
         /*
          * .exit.text is discard at runtime, not link time, to deal with
          *  references from .altinstructions and .eh_frame