x86/amd-iommu: Add an index field to struct amd_iommu

This patch adds an index field to struct amd_iommu which can
be used to lookup it up in an array. This index will be used
in struct protection_domain to keep track which protection
domain has devices behind which IOMMU.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/include/asm/amd_iommu_types.h

@@ -24,6 +24,11 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 
+/*
+ * Maximum number of IOMMUs supported
+ */
+#define MAX_IOMMUS	32
+
 /*
  * some size calculation constants
  */
@@ -291,6 +296,9 @@ struct dma_ops_domain {
 struct amd_iommu {
 	struct list_head list;
 
+	/* Index within the IOMMU array */
+	int index;
+
 	/* locks the accesses to the hardware */
 	spinlock_t lock;
 
@@ -356,6 +364,15 @@ struct amd_iommu {
  */
 extern struct list_head amd_iommu_list;
 
+/*
+ * Array with pointers to each IOMMU struct
+ * The indices are referenced in the protection domains
+ */
+extern struct amd_iommu *amd_iommus[MAX_IOMMUS];
+
+/* Number of IOMMUs present in the system */
+extern int amd_iommus_present;
+
 /*
  * Structure defining one entry in the device table
  */

arch/x86/kernel/amd_iommu_init.c

@@ -137,6 +137,10 @@ bool amd_iommu_unmap_flush;		/* if true, flush on every unmap */
 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
 					   system */
 
+/* Array to assign indices to IOMMUs*/
+struct amd_iommu *amd_iommus[MAX_IOMMUS];
+int amd_iommus_present;
+
 /*
  * Pointer to the device table which is shared by all AMD IOMMUs
  * it is indexed by the PCI device id or the HT unit id and contains
@@ -840,7 +844,18 @@ static void __init free_iommu_all(void)
 static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
 {
 	spin_lock_init(&iommu->lock);
+
+	/* Add IOMMU to internal data structures */
 	list_add_tail(&iommu->list, &amd_iommu_list);
+	iommu->index             = amd_iommus_present++;
+
+	if (unlikely(iommu->index >= MAX_IOMMUS)) {
+		WARN(1, "AMD-Vi: System has more IOMMUs than supported by this driver\n");
+		return -ENOSYS;
+	}
+
+	/* Index is fine - add IOMMU to the array */
+	amd_iommus[iommu->index] = iommu;
 
 	/*
 	 * Copy data from ACPI table entry to the iommu struct