Sophie

Sophie

distrib > Scientific%20Linux > 5x > x86_64 > by-pkgid > 89877e42827f16fa5f86b1df0c2860b1 > files > 2523

kernel-2.6.18-128.1.10.el5.src.rpm

From: Bhavna Sarathy <bnagendr@redhat.com>
Date: Tue, 19 Aug 2008 11:46:10 -0400
Subject: [x86_64] AMD IOMMU driver support
Message-id: 48AAEAC2.2040908@redhat.com
O-Subject: Re: [RHEL5.3 PATCH 1/2] AMD IOMMU driver support
Bugzilla: 251970
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Brian Maly <bmaly@redhat.com>

Resolves BZ 251970

Adding AMD IOMMU x86_64 driver support - the driver supports DMA remapping using
IOMMU helper functions and dma_ops support.  It also supports device isolation
of DMA address spaces if hardware allows it.

Per discussions with PeterM, the AMD IOMMU driver is disabled by default in
RHEL5.3 and can be enabled through kernel options.   The kernel option for enabling
the driver is iommu="amd" and to enable device isolation
amd_iommu="isolation".

AMD_IOMMU and IOMMU_HELPER configurations however, need to be enabled in RHEL5.3,
to allow for the AMD IOMMU modules to be built and supported.  See patch 2/2 for
the config patch.

Dependencies: Prarit submitted "GART IOMMU alignment fixes" that updated GART
to use upstream IOMMU helper routines.  I need these IOMMU helper functions in
order for the AMD IOMMU driver to be built without errors.

I have enabled IOMMU_HELPER in this patch depending on whether AMD_IOMMU or
GART_IOMMU is enabled.

Upstream status:  AMD IOMMU driver has been accepted into 2.6.27 and is present
in the 2.6.27-rc2 patch I downloaded last week from kernel.org.

Testing: I used RD890 FPGA system for development and testing.  The backported
driver successfully boots up on this system, and has been tested under load.
An x86_64 RHEL5.3 RPM with the back ported driver was tested on another RD890
system with identical results.

Please review and ACK.

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a62103a..b5bbd11 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -226,6 +226,18 @@ running once the system is up.
 	aic79xx=	[HW,SCSI]
 			See Documentation/scsi/aic79xx.txt.
 
+        amd_iommu=      [HW, X86_64]
+			Pass parameter to the AMD IOMMU driver in the system
+			Note that enabling the driver is done by passing in iommu=
+			Enable use iommu="amd" 
+			isolate - enable device isolation (each device could get 
+			it's own protection domain
+
+	amd_iommu_size= [HW,X86-64]
+			Define the size of the aperture for the AMD IOMMU
+			driver.  Possible values are:
+			'32M', '64M' (default), '128M', '256M', '512M', '1G'
+
 	amijoy.map=	[HW,JOY] Amiga joystick support
 			Map of devices attached to JOY0DAT and JOY1DAT
 			Format: <a>,<b>
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index e1bfe98..ee50cdc 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -512,6 +512,26 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT
 	  Calgary anyway, pass 'iommu=calgary' on the kernel command line.
 	  If unsure, say Y.
 
+config AMD_IOMMU
+	bool "AMD IOMMU support"
+	select SWIOTLB
+	depends on X86_64 && PCI && ACPI
+	help
+	  With this option you can enable support for AMD IOMMU hardware in
+	  your system. An IOMMU is a hardware component which provides
+	  remapping of DMA memory accesses from devices. With an AMD IOMMU you
+	  can isolate the the DMA memory of different devices and protect the
+	  system from misbehaving device drivers or hardware.
+
+	  You can find out if your system has an AMD IOMMU if you look into
+	  your BIOS for an option to enable it or if you have an IVRS ACPI
+	  table.
+
+config IOMMU_HELPER
+	bool "IOMMU Helper functions"
+	default n
+	depends on (AMD_IOMMU || GART_IOMMU)
+
 # need this always selected by IOMMU for the VIA workaround
 config SWIOTLB
 	bool
diff --git a/arch/x86_64/kernel/Makefile b/arch/x86_64/kernel/Makefile
index dcec5ae..5f427b4 100644
--- a/arch/x86_64/kernel/Makefile
+++ b/arch/x86_64/kernel/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_EFI)              += efi.o efi_callwrap.o
 
 obj-$(CONFIG_MODULES)		+= module.o
 obj-$(CONFIG_X86_LOCAL_APIC)	+= perfctr-watchdog.o
+obj-$(CONFIG_AMD_IOMMU)		+= amd_iommu_init.o amd_iommu.o
 
 obj-y				+= topology.o
 obj-y				+= intel_cacheinfo.o
diff --git a/arch/x86_64/kernel/amd_iommu.c b/arch/x86_64/kernel/amd_iommu.c
new file mode 100644
index 0000000..25bebff
--- /dev/null
+++ b/arch/x86_64/kernel/amd_iommu.c
@@ -0,0 +1,1174 @@
+/*
+ * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
+ * Author: Joerg Roedel <joerg.roedel@amd.com>
+ *         Leo Duran <leo.duran@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/pci.h>
+#include <linux/gfp.h>
+#include <linux/bitops.h>
+#include <linux/scatterlist.h>
+#include <linux/iommu-helper.h>
+#include <asm/proto.h>
+#include <asm/amd_iommu_types.h>
+#include <asm/amd_iommu.h>
+#include <linux/delay.h>
+
+#define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))
+
+#define EXIT_LOOP_COUNT 10000000
+
+static DEFINE_RWLOCK(amd_iommu_devtable_lock);
+
+/*
+ * general struct to manage commands send to an IOMMU
+ */
+struct iommu_cmd {
+	u32 data[4];
+};
+
+static int dma_ops_unity_map(struct dma_ops_domain *dma_dom,
+			     struct unity_map_entry *e);
+
+/* returns !0 if the IOMMU is caching non-present entries in its TLB */
+static int iommu_has_npcache(struct amd_iommu *iommu)
+{
+	return iommu->cap & IOMMU_CAP_NPCACHE;
+}
+
+/****************************************************************************
+ *
+ * IOMMU command queuing functions
+ *
+ ****************************************************************************/
+
+/*
+ * Writes the command to the IOMMUs command buffer and informs the
+ * hardware about the new command. Must be called with iommu->lock held.
+ */
+static int __iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
+{
+	u32 tail, head;
+	u8 *target;
+
+	tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
+	target = (iommu->cmd_buf + tail);
+	memcpy_toio(target, cmd, sizeof(*cmd));
+	tail = (tail + sizeof(*cmd)) % iommu->cmd_buf_size;
+	head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
+	if (tail == head)
+		return -ENOMEM;
+	writel(tail, iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
+
+	return 0;
+}
+
+/*
+ * General queuing function for commands. Takes iommu->lock and calls
+ * __iommu_queue_command().
+ */
+static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&iommu->lock, flags);
+	ret = __iommu_queue_command(iommu, cmd);
+	spin_unlock_irqrestore(&iommu->lock, flags);
+
+	return ret;
+}
+
+/*
+ * This function is called whenever we need to ensure that the IOMMU has
+ * completed execution of all commands we sent. It sends a
+ * COMPLETION_WAIT command and waits for it to finish. The IOMMU informs
+ * us about that by writing a value to a physical address we pass with
+ * the command.
+ */
+static int iommu_completion_wait(struct amd_iommu *iommu)
+{
+	int ret, i = 0;
+	u32 status = 0, ready = 0;
+	struct iommu_cmd cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
+	CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT);
+
+	iommu->need_sync = 0;
+
+	ret = iommu_queue_command(iommu, &cmd);
+
+	if (ret)
+		return ret;
+
+	while (!ready && (i < EXIT_LOOP_COUNT)) {
+		++i;
+		status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
+		ready = status & IOMMU_STATUS_COMWAITINT_MASK;
+		cpu_relax();
+	}
+	status &= ~IOMMU_STATUS_COMWAITINT_MASK;
+	writel(status, iommu->mmio_base + MMIO_STATUS_OFFSET);
+
+	if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
+		printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");
+
+	return 0;
+}
+
+/*
+ * Command send function for invalidating a device table entry
+ */
+static int iommu_queue_inv_dev_entry(struct amd_iommu *iommu, u16 devid)
+{
+	struct iommu_cmd cmd;
+
+	BUG_ON(iommu == NULL);
+
+	memset(&cmd, 0, sizeof(cmd));
+	CMD_SET_TYPE(&cmd, CMD_INV_DEV_ENTRY);
+	cmd.data[0] = devid;
+
+	iommu->need_sync = 1;
+
+	return iommu_queue_command(iommu, &cmd);
+}
+
+/*
+ * Generic command send function for invalidaing TLB entries
+ */
+static int iommu_queue_inv_iommu_pages(struct amd_iommu *iommu,
+		u64 address, u16 domid, int pde, int s)
+{
+	struct iommu_cmd cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	address &= PAGE_MASK;
+	CMD_SET_TYPE(&cmd, CMD_INV_IOMMU_PAGES);
+	cmd.data[1] |= domid;
+	cmd.data[2] = LOW_U32(address);
+	cmd.data[3] = HIGH_U32(address);
+	if (s) /* size bit - we flush more than one 4kb page */
+		cmd.data[2] |= CMD_INV_IOMMU_PAGES_SIZE_MASK;
+	if (pde) /* PDE bit - we wan't flush everything not only the PTEs */
+		cmd.data[2] |= CMD_INV_IOMMU_PAGES_PDE_MASK;
+
+	iommu->need_sync = 1;
+
+	return iommu_queue_command(iommu, &cmd);
+}
+
+/*
+ * TLB invalidation function which is called from the mapping functions.
+ * It invalidates a single PTE if the range to flush is within a single
+ * page. Otherwise it flushes the whole TLB of the IOMMU.
+ */
+static int iommu_flush_pages(struct amd_iommu *iommu, u16 domid,
+		u64 address, size_t size)
+{
+	int s = 0;
+	unsigned pages = iommu_num_pages(address, size);
+
+	address &= PAGE_MASK;
+
+	if (pages > 1) {
+		/*
+		 * If we have to flush more than one page, flush all
+		 * TLB entries for this domain
+		 */
+		address = CMD_INV_IOMMU_ALL_PAGES_ADDRESS;
+		s = 1;
+	}
+
+	iommu_queue_inv_iommu_pages(iommu, address, domid, 0, s);
+
+	return 0;
+}
+
+/****************************************************************************
+ *
+ * The functions below are used the create the page table mappings for
+ * unity mapped regions.
+ *
+ ****************************************************************************/
+
+/*
+ * Generic mapping functions. It maps a physical address into a DMA
+ * address space. It allocates the page table pages if necessary.
+ * In the future it can be extended to a generic mapping function
+ * supporting all features of AMD IOMMU page tables like level skipping
+ * and full 64 bit address spaces.
+ */
+static int iommu_map(struct protection_domain *dom,
+		     unsigned long bus_addr,
+		     unsigned long phys_addr,
+		     int prot)
+{
+	u64 __pte, *pte, *page;
+
+	bus_addr  = PAGE_ALIGN(bus_addr);
+	phys_addr = PAGE_ALIGN(bus_addr);
+
+	/* only support 512GB address spaces for now */
+	if (bus_addr > IOMMU_MAP_SIZE_L3 || !(prot & IOMMU_PROT_MASK))
+		return -EINVAL;
+
+	pte = &dom->pt_root[IOMMU_PTE_L2_INDEX(bus_addr)];
+
+	if (!IOMMU_PTE_PRESENT(*pte)) {
+		page = (u64 *)get_zeroed_page(GFP_KERNEL);
+		if (!page)
+			return -ENOMEM;
+		*pte = IOMMU_L2_PDE(virt_to_phys(page));
+	}
+
+	pte = IOMMU_PTE_PAGE(*pte);
+	pte = &pte[IOMMU_PTE_L1_INDEX(bus_addr)];
+
+	if (!IOMMU_PTE_PRESENT(*pte)) {
+		page = (u64 *)get_zeroed_page(GFP_KERNEL);
+		if (!page)
+			return -ENOMEM;
+		*pte = IOMMU_L1_PDE(virt_to_phys(page));
+	}
+
+	pte = IOMMU_PTE_PAGE(*pte);
+	pte = &pte[IOMMU_PTE_L0_INDEX(bus_addr)];
+
+	if (IOMMU_PTE_PRESENT(*pte))
+		return -EBUSY;
+
+	__pte = phys_addr | IOMMU_PTE_P;
+	if (prot & IOMMU_PROT_IR)
+		__pte |= IOMMU_PTE_IR;
+	if (prot & IOMMU_PROT_IW)
+		__pte |= IOMMU_PTE_IW;
+
+	*pte = __pte;
+
+	return 0;
+}
+
+/*
+ * This function checks if a specific unity mapping entry is needed for
+ * this specific IOMMU.
+ */
+static int iommu_for_unity_map(struct amd_iommu *iommu,
+			       struct unity_map_entry *entry)
+{
+	u16 bdf, i;
+
+	for (i = entry->devid_start; i <= entry->devid_end; ++i) {
+		bdf = amd_iommu_alias_table[i];
+		if (amd_iommu_rlookup_table[bdf] == iommu)
+			return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Init the unity mappings for a specific IOMMU in the system
+ *
+ * Basically iterates over all unity mapping entries and applies them to
+ * the default domain DMA of that IOMMU if necessary.
+ */
+static int iommu_init_unity_mappings(struct amd_iommu *iommu)
+{
+	struct unity_map_entry *entry;
+	int ret;
+
+	list_for_each_entry(entry, &amd_iommu_unity_map, list) {
+		if (!iommu_for_unity_map(iommu, entry))
+			continue;
+		ret = dma_ops_unity_map(iommu->default_dom, entry);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * This function actually applies the mapping to the page table of the
+ * dma_ops domain.
+ */
+static int dma_ops_unity_map(struct dma_ops_domain *dma_dom,
+			     struct unity_map_entry *e)
+{
+	u64 addr;
+	int ret;
+
+	for (addr = e->address_start; addr < e->address_end;
+	     addr += PAGE_SIZE) {
+		ret = iommu_map(&dma_dom->domain, addr, addr, e->prot);
+		if (ret)
+			return ret;
+		/*
+		 * if unity mapping is in aperture range mark the page
+		 * as allocated in the aperture
+		 */
+		if (addr < dma_dom->aperture_size)
+			__set_bit(addr >> PAGE_SHIFT, dma_dom->bitmap);
+	}
+
+	return 0;
+}
+
+/*
+ * Inits the unity mappings required for a specific device
+ */
+static int init_unity_mappings_for_device(struct dma_ops_domain *dma_dom,
+					  u16 devid)
+{
+	struct unity_map_entry *e;
+	int ret;
+
+	list_for_each_entry(e, &amd_iommu_unity_map, list) {
+		if (!(devid >= e->devid_start && devid <= e->devid_end))
+			continue;
+		ret = dma_ops_unity_map(dma_dom, e);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/****************************************************************************
+ *
+ * The next functions belong to the address allocator for the dma_ops
+ * interface functions. They work like the allocators in the other IOMMU
+ * drivers. Its basically a bitmap which marks the allocated pages in
+ * the aperture. Maybe it could be enhanced in the future to a more
+ * efficient allocator.
+ *
+ ****************************************************************************/
+static unsigned long dma_mask_to_pages(unsigned long mask)
+{
+	return (mask >> PAGE_SHIFT) +
+		(PAGE_ALIGN(mask & ~PAGE_MASK) >> PAGE_SHIFT);
+}
+
+/*
+ * The address allocator core function.
+ *
+ * called with domain->lock held
+ */
+static unsigned long dma_ops_alloc_addresses(struct device *dev,
+					     struct dma_ops_domain *dom,
+					     unsigned int pages)
+{
+	unsigned long limit = dma_mask_to_pages(*dev->dma_mask);
+	unsigned long address;
+	unsigned long size = dom->aperture_size >> PAGE_SHIFT;
+	unsigned long boundary_size;
+
+	boundary_size = ALIGN(0xffffffffUL + 1,
+			PAGE_SIZE) >> PAGE_SHIFT;
+	limit = limit < size ? limit : size;
+
+	if (dom->next_bit >= limit)
+		dom->next_bit = 0;
+
+	address = iommu_area_alloc(dom->bitmap, limit, dom->next_bit, pages,
+			0 , boundary_size, 0);
+	if (address == -1)
+		address = iommu_area_alloc(dom->bitmap, limit, 0, pages,
+				0, boundary_size, 0);
+
+	if (likely(address != -1)) {
+		dom->next_bit = address + pages;
+		address <<= PAGE_SHIFT;
+	} else
+		address = bad_dma_address;
+
+	WARN_ON((address + (PAGE_SIZE*pages)) > dom->aperture_size);
+
+	return address;
+}
+
+/*
+ * The address free function.
+ *
+ * called with domain->lock held
+ */
+static void dma_ops_free_addresses(struct dma_ops_domain *dom,
+				   unsigned long address,
+				   unsigned int pages)
+{
+	address >>= PAGE_SHIFT;
+	iommu_area_free(dom->bitmap, address, pages);
+}
+
+/****************************************************************************
+ *
+ * The next functions belong to the domain allocation. A domain is
+ * allocated for every IOMMU as the default domain. If device isolation
+ * is enabled, every device get its own domain. The most important thing
+ * about domains is the page table mapping the DMA address space they
+ * contain.
+ *
+ ****************************************************************************/
+
+static u16 domain_id_alloc(void)
+{
+	unsigned long flags;
+	int id;
+
+	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	id = find_first_zero_bit(amd_iommu_pd_alloc_bitmap, MAX_DOMAIN_ID);
+	BUG_ON(id == 0);
+	if (id > 0 && id < MAX_DOMAIN_ID)
+		__set_bit(id, amd_iommu_pd_alloc_bitmap);
+	else
+		id = 0;
+	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+
+	return id;
+}
+
+/*
+ * Used to reserve address ranges in the aperture (e.g. for exclusion
+ * ranges.
+ */
+static void dma_ops_reserve_addresses(struct dma_ops_domain *dom,
+				      unsigned long start_page,
+				      unsigned int pages)
+{
+	unsigned int last_page = dom->aperture_size >> PAGE_SHIFT;
+
+	if (start_page + pages > last_page)
+		pages = last_page - start_page;
+
+	set_bit_string(dom->bitmap, start_page, pages);
+}
+
+static void dma_ops_free_pagetable(struct dma_ops_domain *dma_dom)
+{
+	int i, j;
+	u64 *p1, *p2, *p3;
+
+	p1 = dma_dom->domain.pt_root;
+
+	if (!p1)
+		return;
+
+	for (i = 0; i < 512; ++i) {
+		if (!IOMMU_PTE_PRESENT(p1[i]))
+			continue;
+
+		p2 = IOMMU_PTE_PAGE(p1[i]);
+		for (j = 0; j < 512; ++i) {
+			if (!IOMMU_PTE_PRESENT(p2[j]))
+				continue;
+			p3 = IOMMU_PTE_PAGE(p2[j]);
+			free_page((unsigned long)p3);
+		}
+
+		free_page((unsigned long)p2);
+	}
+
+	free_page((unsigned long)p1);
+}
+
+/*
+ * Free a domain, only used if something went wrong in the
+ * allocation path and we need to free an already allocated page table
+ */
+static void dma_ops_domain_free(struct dma_ops_domain *dom)
+{
+	if (!dom)
+		return;
+
+	dma_ops_free_pagetable(dom);
+
+	kfree(dom->pte_pages);
+
+	kfree(dom->bitmap);
+
+	kfree(dom);
+}
+
+/*
+ * Allocates a new protection domain usable for the dma_ops functions.
+ * It also intializes the page table and the address allocator data
+ * structures required for the dma_ops interface
+ */
+static struct dma_ops_domain *dma_ops_domain_alloc(struct amd_iommu *iommu,
+						   unsigned order)
+{
+	struct dma_ops_domain *dma_dom;
+	unsigned i, num_pte_pages;
+	u64 *l2_pde;
+	u64 address;
+
+	/*
+	 * Currently the DMA aperture must be between 32 MB and 1GB in size
+	 */
+	if ((order < 25) || (order > 30))
+		return NULL;
+
+	dma_dom = kzalloc(sizeof(struct dma_ops_domain), GFP_KERNEL);
+	if (!dma_dom)
+		return NULL;
+
+	spin_lock_init(&dma_dom->domain.lock);
+
+	dma_dom->domain.id = domain_id_alloc();
+	if (dma_dom->domain.id == 0)
+		goto free_dma_dom;
+	dma_dom->domain.mode = PAGE_MODE_3_LEVEL;
+	dma_dom->domain.pt_root = (void *)get_zeroed_page(GFP_KERNEL);
+	dma_dom->domain.priv = dma_dom;
+	if (!dma_dom->domain.pt_root)
+		goto free_dma_dom;
+	dma_dom->aperture_size = (1ULL << order);
+	dma_dom->bitmap = kzalloc(dma_dom->aperture_size / (PAGE_SIZE * 8),
+				  GFP_KERNEL);
+	if (!dma_dom->bitmap)
+		goto free_dma_dom;
+	/*
+	 * mark the first page as allocated so we never return 0 as
+	 * a valid dma-address. So we can use 0 as error value
+	 */
+	dma_dom->bitmap[0] = 1;
+	dma_dom->next_bit = 0;
+
+	/* Intialize the exclusion range if necessary */
+	if (iommu->exclusion_start &&
+	    iommu->exclusion_start < dma_dom->aperture_size) {
+		unsigned long startpage = iommu->exclusion_start >> PAGE_SHIFT;
+		int pages = iommu_num_pages(iommu->exclusion_start,
+					    iommu->exclusion_length);
+		dma_ops_reserve_addresses(dma_dom, startpage, pages);
+	}
+
+	/*
+	 * At the last step, build the page tables so we don't need to
+	 * allocate page table pages in the dma_ops mapping/unmapping
+	 * path.
+	 */
+	num_pte_pages = dma_dom->aperture_size / (PAGE_SIZE * 512);
+	dma_dom->pte_pages = kzalloc(num_pte_pages * sizeof(void *),
+			GFP_KERNEL);
+	if (!dma_dom->pte_pages)
+		goto free_dma_dom;
+
+	l2_pde = (u64 *)get_zeroed_page(GFP_KERNEL);
+	if (l2_pde == NULL)
+		goto free_dma_dom;
+
+	dma_dom->domain.pt_root[0] = IOMMU_L2_PDE(virt_to_phys(l2_pde));
+
+	for (i = 0; i < num_pte_pages; ++i) {
+		dma_dom->pte_pages[i] = (u64 *)get_zeroed_page(GFP_KERNEL);
+		if (!dma_dom->pte_pages[i])
+			goto free_dma_dom;
+		address = virt_to_phys(dma_dom->pte_pages[i]);
+		l2_pde[i] = IOMMU_L1_PDE(address);
+	}
+
+	return dma_dom;
+
+free_dma_dom:
+	dma_ops_domain_free(dma_dom);
+
+	return NULL;
+}
+
+/*
+ * Find out the protection domain structure for a given PCI device. This
+ * will give us the pointer to the page table root for example.
+ */
+static struct protection_domain *domain_for_device(u16 devid)
+{
+	struct protection_domain *dom;
+	unsigned long flags;
+
+	read_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	dom = amd_iommu_pd_table[devid];
+	read_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+
+	return dom;
+}
+
+/*
+ * If a device is not yet associated with a domain, this function does
+ * assigns it visible for the hardware
+ */
+static void set_device_domain(struct amd_iommu *iommu,
+			      struct protection_domain *domain,
+			      u16 devid)
+{
+	unsigned long flags;
+
+	u64 pte_root = virt_to_phys(domain->pt_root);
+
+	pte_root |= (domain->mode & 0x07) << 9;
+	pte_root |= IOMMU_PTE_IR | IOMMU_PTE_IW | IOMMU_PTE_P | 2;
+
+	write_lock_irqsave(&amd_iommu_devtable_lock, flags);
+	amd_iommu_dev_table[devid].data[0] = pte_root;
+	amd_iommu_dev_table[devid].data[1] = pte_root >> 32;
+	amd_iommu_dev_table[devid].data[2] = domain->id;
+
+	amd_iommu_pd_table[devid] = domain;
+	write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+
+	iommu_queue_inv_dev_entry(iommu, devid);
+
+	iommu->need_sync = 1;
+}
+
+/*****************************************************************************
+ *
+ * The next functions belong to the dma_ops mapping/unmapping code.
+ *
+ *****************************************************************************/
+
+/*
+ * In the dma_ops path we only have the struct device. This function
+ * finds the corresponding IOMMU, the protection domain and the
+ * requestor id for a given device.
+ * If the device is not yet associated with a domain this is also done
+ * in this function.
+ */
+static int get_device_resources(struct device *dev,
+				struct amd_iommu **iommu,
+				struct protection_domain **domain,
+				u16 *bdf)
+{
+	struct dma_ops_domain *dma_dom;
+	struct pci_dev *pcidev;
+	u16 _bdf;
+
+	if (!dev || dev->bus != &pci_bus_type || !dev->dma_mask) {
+		*iommu = NULL;
+		*domain = NULL;
+		*bdf = 0xffff;
+		return 0;
+	}
+
+	pcidev = to_pci_dev(dev);
+	_bdf = calc_devid(pcidev->bus->number, pcidev->devfn);
+
+	/* device not translated by any IOMMU in the system? */
+	if (_bdf > amd_iommu_last_bdf) {
+		*iommu = NULL;
+		*domain = NULL;
+		*bdf = 0xffff;
+		return 0;
+	}
+
+	*bdf = amd_iommu_alias_table[_bdf];
+
+	*iommu = amd_iommu_rlookup_table[*bdf];
+	if (*iommu == NULL)
+		return 0;
+	dma_dom = (*iommu)->default_dom;
+	*domain = domain_for_device(*bdf);
+	if (*domain == NULL) {
+		*domain = &dma_dom->domain;
+		set_device_domain(*iommu, *domain, *bdf);
+		printk(KERN_INFO "AMD IOMMU: Using protection domain %d for "
+				"device ", (*domain)->id);
+		print_devid(_bdf, 1);
+	}
+
+	return 1;
+}
+
+/*
+ * This is the generic map function. It maps one 4kb page at paddr to
+ * the given address in the DMA address space for the domain.
+ */
+static dma_addr_t dma_ops_domain_map(struct amd_iommu *iommu,
+				     struct dma_ops_domain *dom,
+				     unsigned long address,
+				     unsigned long paddr,
+				     int direction)
+{
+	u64 *pte, __pte;
+
+	WARN_ON(address > dom->aperture_size);
+
+	paddr &= PAGE_MASK;
+
+	pte  = dom->pte_pages[IOMMU_PTE_L1_INDEX(address)];
+	pte += IOMMU_PTE_L0_INDEX(address);
+
+	__pte = paddr | IOMMU_PTE_P | IOMMU_PTE_FC;
+
+	if (direction == DMA_TO_DEVICE)
+		__pte |= IOMMU_PTE_IR;
+	else if (direction == DMA_FROM_DEVICE)
+		__pte |= IOMMU_PTE_IW;
+	else if (direction == DMA_BIDIRECTIONAL)
+		__pte |= IOMMU_PTE_IR | IOMMU_PTE_IW;
+
+	WARN_ON(*pte);
+
+	*pte = __pte;
+
+	return (dma_addr_t)address;
+}
+
+/*
+ * The generic unmapping function for on page in the DMA address space.
+ */
+static void dma_ops_domain_unmap(struct amd_iommu *iommu,
+				 struct dma_ops_domain *dom,
+				 unsigned long address)
+{
+	u64 *pte;
+
+	if (address >= dom->aperture_size)
+		return;
+
+	WARN_ON(address & 0xfffULL || address > dom->aperture_size);
+
+	pte  = dom->pte_pages[IOMMU_PTE_L1_INDEX(address)];
+	pte += IOMMU_PTE_L0_INDEX(address);
+
+	WARN_ON(!*pte);
+
+	*pte = 0ULL;
+}
+
+/*
+ * This function contains common code for mapping of a physically
+ * contiguous memory region into DMA address space. It is uses by all
+ * mapping functions provided by this IOMMU driver.
+ * Must be called with the domain lock held.
+ */
+static dma_addr_t __map_single(struct device *dev,
+			       struct amd_iommu *iommu,
+			       struct dma_ops_domain *dma_dom,
+			       unsigned long paddr,
+			       size_t size,
+			       int dir)
+{
+	dma_addr_t offset = paddr & ~PAGE_MASK;
+	dma_addr_t address, start;
+	unsigned int pages;
+	int i;
+
+	pages = iommu_num_pages(paddr, size);
+	paddr &= PAGE_MASK;
+
+	address = dma_ops_alloc_addresses(dev, dma_dom, pages);
+	if (unlikely(address == bad_dma_address))
+		goto out;
+
+	start = address;
+	for (i = 0; i < pages; ++i) {
+		dma_ops_domain_map(iommu, dma_dom, start, paddr, dir);
+		paddr += PAGE_SIZE;
+		start += PAGE_SIZE;
+	}
+	address += offset;
+
+out:
+	return address;
+}
+
+/*
+ * Does the reverse of the __map_single function. Must be called with
+ * the domain lock held too
+ */
+static void __unmap_single(struct amd_iommu *iommu,
+			   struct dma_ops_domain *dma_dom,
+			   dma_addr_t dma_addr,
+			   size_t size,
+			   int dir)
+{
+	dma_addr_t i, start;
+	unsigned int pages;
+
+	if ((dma_addr == 0) || (dma_addr + size > dma_dom->aperture_size))
+		return;
+
+	pages = iommu_num_pages(dma_addr, size);
+	dma_addr &= PAGE_MASK;
+	start = dma_addr;
+
+	for (i = 0; i < pages; ++i) {
+		dma_ops_domain_unmap(iommu, dma_dom, start);
+		start += PAGE_SIZE;
+	}
+
+	dma_ops_free_addresses(dma_dom, dma_addr, pages);
+}
+
+/*
+ * The exported map_single function for dma_ops.
+ */
+static dma_addr_t map_single(struct device *dev, void *vaddr,
+			     size_t size, int dir)
+{
+	unsigned long flags;
+	struct amd_iommu *iommu;
+	struct protection_domain *domain;
+	u16 devid;
+	dma_addr_t addr;
+	unsigned long paddr = __pa(vaddr);
+
+	get_device_resources(dev, &iommu, &domain, &devid);
+
+	if (iommu == NULL || domain == NULL)
+		/* device not handled by any AMD IOMMU */
+		return (dma_addr_t)paddr;
+
+	spin_lock_irqsave(&domain->lock, flags);
+	addr = __map_single(dev, iommu, domain->priv, paddr, size, dir);
+	if (addr == bad_dma_address)
+		goto out;
+
+	if (iommu_has_npcache(iommu))
+		iommu_flush_pages(iommu, domain->id, addr, size);
+
+	if (iommu->need_sync)
+		iommu_completion_wait(iommu);
+
+out:
+	spin_unlock_irqrestore(&domain->lock, flags);
+
+	return addr;
+}
+
+/*
+ * The exported unmap_single function for dma_ops.
+ */
+static void unmap_single(struct device *dev, dma_addr_t dma_addr,
+			 size_t size, int dir)
+{
+	unsigned long flags;
+	struct amd_iommu *iommu;
+	struct protection_domain *domain;
+	u16 devid;
+
+	if (!get_device_resources(dev, &iommu, &domain, &devid))
+		/* device not handled by any AMD IOMMU */
+		return;
+
+	spin_lock_irqsave(&domain->lock, flags);
+
+	__unmap_single(iommu, domain->priv, dma_addr, size, dir);
+
+	iommu_flush_pages(iommu, domain->id, dma_addr, size);
+
+	if (iommu->need_sync)
+		iommu_completion_wait(iommu);
+
+	spin_unlock_irqrestore(&domain->lock, flags);
+}
+
+/*
+ * This is a special map_sg function which is used if we should map a
+ * device which is not handled by an AMD IOMMU in the system.
+ */
+static int map_sg_no_iommu(struct device *dev, struct scatterlist *sglist,
+			   int nelems, int dir)
+{
+	struct scatterlist *s;
+	int i;
+
+	for (i = 0; i < nelems; ++i) {
+		s = &sglist[i];
+		s->dma_address = (dma_addr_t)(page_to_phys(s->page)+s->offset);
+		s->dma_length = s->length;
+	}
+
+	return nelems;
+}
+
+/*
+ * The exported map_sg function for dma_ops (handles scatter-gather
+ * lists).
+ */
+static int map_sg(struct device *dev, struct scatterlist *sglist,
+		  int nelems, int dir)
+{
+	unsigned long flags;
+	struct amd_iommu *iommu;
+	struct protection_domain *domain;
+	u16 devid;
+	int i;
+	struct scatterlist *s;
+	unsigned long paddr;
+	int mapped_elems = 0;
+
+	get_device_resources(dev, &iommu, &domain, &devid);
+
+	if (!iommu || !domain)
+		return map_sg_no_iommu(dev, sglist, nelems, dir);
+
+	spin_lock_irqsave(&domain->lock, flags);
+
+	for (i = 0; i < nelems; ++i) {
+		s = &sglist[i];
+		paddr = page_to_phys(s->page) + s->offset;
+
+		s->dma_address = __map_single(dev, iommu, domain->priv,
+					      paddr, s->length, dir);
+
+		if (s->dma_address) {
+			s->dma_length = s->length;
+			mapped_elems++;
+		} else
+			goto unmap;
+		if (iommu_has_npcache(iommu))
+			iommu_flush_pages(iommu, domain->id, s->dma_address,
+					  s->dma_length);
+	}
+
+	if (iommu->need_sync)
+		iommu_completion_wait(iommu);
+
+out:
+	spin_unlock_irqrestore(&domain->lock, flags);
+
+	return mapped_elems;
+unmap:
+	for (i = 0; i < mapped_elems; ++i) {
+		s = &sglist[i];
+		if (s->dma_address)
+			__unmap_single(iommu, domain->priv, s->dma_address,
+				       s->dma_length, dir);
+		s->dma_address = s->dma_length = 0;
+	}
+
+	mapped_elems = 0;
+
+	goto out;
+}
+
+/*
+ * The exported map_sg function for dma_ops (handles scatter-gather
+ * lists).
+ */
+static void unmap_sg(struct device *dev, struct scatterlist *sglist,
+		     int nelems, int dir)
+{
+	unsigned long flags;
+	struct amd_iommu *iommu;
+	struct protection_domain *domain;
+	struct scatterlist *s;
+	u16 devid;
+	int i;
+
+	if (!get_device_resources(dev, &iommu, &domain, &devid))
+		return;
+
+	spin_lock_irqsave(&domain->lock, flags);
+
+	for (i = 0; i < nelems; ++i) {
+		s = &sglist[i];
+		__unmap_single(iommu, domain->priv, s->dma_address,
+			       s->dma_length, dir);
+		iommu_flush_pages(iommu, domain->id, s->dma_address,
+				  s->dma_length);
+		s->dma_address = 0;
+	}
+
+	if (iommu->need_sync)
+		iommu_completion_wait(iommu);
+
+	spin_unlock_irqrestore(&domain->lock, flags);
+}
+
+/*
+ * The exported alloc_coherent function for dma_ops.
+ */
+static void *alloc_coherent(struct device *dev, size_t size,
+			    dma_addr_t *dma_addr, gfp_t flag)
+{
+	unsigned long flags;
+	void *virt_addr;
+	struct amd_iommu *iommu;
+	struct protection_domain *domain;
+	u16 devid;
+	unsigned long paddr;
+
+	virt_addr = (void *)__get_free_pages(flag, get_order(size));
+	if (!virt_addr)
+		return 0;
+
+	memset(virt_addr, 0, size);
+	paddr = virt_to_phys(virt_addr);
+
+	get_device_resources(dev, &iommu, &domain, &devid);
+
+	if (!iommu || !domain) {
+		*dma_addr = (dma_addr_t)paddr;
+		return virt_addr;
+	}
+
+	spin_lock_irqsave(&domain->lock, flags);
+
+	*dma_addr = __map_single(dev, iommu, domain->priv, paddr,
+				 size, DMA_BIDIRECTIONAL);
+
+	if (*dma_addr == bad_dma_address) {
+		free_pages((unsigned long)virt_addr, get_order(size));
+		virt_addr = NULL;
+		goto out;
+	}
+
+	if (iommu_has_npcache(iommu))
+		iommu_flush_pages(iommu, domain->id, *dma_addr, size);
+
+	if (iommu->need_sync)
+		iommu_completion_wait(iommu);
+
+out:
+	spin_unlock_irqrestore(&domain->lock, flags);
+
+	return virt_addr;
+}
+
+/*
+ * The exported free_coherent function for dma_ops.
+ * FIXME: fix the generic x86 DMA layer so that it actually calls that
+ *        function.
+ */
+static void free_coherent(struct device *dev, size_t size,
+			  void *virt_addr, dma_addr_t dma_addr)
+{
+	unsigned long flags;
+	struct amd_iommu *iommu;
+	struct protection_domain *domain;
+	u16 devid;
+
+	get_device_resources(dev, &iommu, &domain, &devid);
+
+	if (!iommu || !domain)
+		goto free_mem;
+
+	spin_lock_irqsave(&domain->lock, flags);
+
+	__unmap_single(iommu, domain->priv, dma_addr, size, DMA_BIDIRECTIONAL);
+	iommu_flush_pages(iommu, domain->id, dma_addr, size);
+
+	if (iommu->need_sync)
+		iommu_completion_wait(iommu);
+
+	spin_unlock_irqrestore(&domain->lock, flags);
+
+free_mem:
+	free_pages((unsigned long)virt_addr, get_order(size));
+}
+
+/*
+ * The function for pre-allocating protection domains.
+ *
+ * If the driver core informs the DMA layer if a driver grabs a device
+ * we don't need to preallocate the protection domains anymore.
+ * For now we have to.
+ */
+void prealloc_protection_domains(void)
+{
+	struct pci_dev *dev = NULL;
+	struct dma_ops_domain *dma_dom;
+	struct amd_iommu *iommu;
+	int order = amd_iommu_aperture_order;
+	u16 devid;
+
+	while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
+		devid = (dev->bus->number << 8) | dev->devfn;
+		if (devid > amd_iommu_last_bdf)
+			continue;
+		devid = amd_iommu_alias_table[devid];
+		if (domain_for_device(devid))
+			continue;
+		iommu = amd_iommu_rlookup_table[devid];
+		if (!iommu)
+			continue;
+		dma_dom = dma_ops_domain_alloc(iommu, order);
+		if (!dma_dom)
+			continue;
+		init_unity_mappings_for_device(dma_dom, devid);
+		set_device_domain(iommu, &dma_dom->domain, devid);
+		printk(KERN_INFO "AMD IOMMU: Allocated domain %d for device ",
+		       dma_dom->domain.id);
+		print_devid(devid, 1);
+	}
+}
+
+static struct dma_mapping_ops amd_iommu_dma_ops = {
+	.alloc_coherent = alloc_coherent,
+	.free_coherent = free_coherent,
+	.map_single = map_single,
+	.unmap_single = unmap_single,
+	.map_sg = map_sg,
+	.unmap_sg = unmap_sg,
+};
+
+/*
+ * The function which clues the AMD IOMMU driver into dma_ops.
+ */
+int __init amd_iommu_init_dma_ops(void)
+{
+	struct amd_iommu *iommu;
+	int order = amd_iommu_aperture_order;
+	int ret;
+
+	/*
+	 * first allocate a default protection domain for every IOMMU we
+	 * found in the system. Devices not assigned to any other
+	 * protection domain will be assigned to the default one.
+	 */
+	list_for_each_entry(iommu, &amd_iommu_list, list) {
+		iommu->default_dom = dma_ops_domain_alloc(iommu, order);
+		if (iommu->default_dom == NULL)
+			return -ENOMEM;
+		ret = iommu_init_unity_mappings(iommu);
+		if (ret)
+			goto free_domains;
+	}
+
+	/*
+	 * If device isolation is enabled, pre-allocate the protection
+	 * domains for each device.
+	 */
+	if (amd_iommu_isolate)
+		prealloc_protection_domains();
+
+	iommu_detected = 1;
+	force_iommu = 1;
+	bad_dma_address = 0;
+#ifdef CONFIG_IOMMU
+	iommu_aperture_disabled = 1;
+	iommu_aperture = 0;
+#endif
+
+	/* Make the driver finally visible to the drivers */
+	dma_ops = &amd_iommu_dma_ops;
+
+	return 0;
+
+free_domains:
+
+	list_for_each_entry(iommu, &amd_iommu_list, list) {
+		if (iommu->default_dom)
+			dma_ops_domain_free(iommu->default_dom);
+	}
+
+	return ret;
+}
diff --git a/arch/x86_64/kernel/amd_iommu_init.c b/arch/x86_64/kernel/amd_iommu_init.c
new file mode 100644
index 0000000..3a6c371
--- /dev/null
+++ b/arch/x86_64/kernel/amd_iommu_init.c
@@ -0,0 +1,1036 @@
+/*
+ * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
+ * Author: Joerg Roedel <joerg.roedel@amd.com>
+ *         Leo Duran <leo.duran@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/pci.h>
+#include <linux/acpi.h>
+#include <linux/gfp.h>
+#include <linux/list.h>
+#include <linux/sysdev.h>
+#include <asm/proto.h>
+#include <asm/pci-direct.h>
+#include <asm/amd_iommu_types.h>
+#include <asm/amd_iommu.h>
+
+/*
+ * definitions for the ACPI scanning code
+ */
+#define PCI_BUS(x) (((x) >> 8) & 0xff)
+#define IVRS_HEADER_LENGTH 48
+
+#define ACPI_IVHD_TYPE                  0x10
+#define ACPI_IVMD_TYPE_ALL              0x20
+#define ACPI_IVMD_TYPE                  0x21
+#define ACPI_IVMD_TYPE_RANGE            0x22
+
+#define IVHD_DEV_ALL                    0x01
+#define IVHD_DEV_SELECT                 0x02
+#define IVHD_DEV_SELECT_RANGE_START     0x03
+#define IVHD_DEV_RANGE_END              0x04
+#define IVHD_DEV_ALIAS                  0x42
+#define IVHD_DEV_ALIAS_RANGE            0x43
+#define IVHD_DEV_EXT_SELECT             0x46
+#define IVHD_DEV_EXT_SELECT_RANGE       0x47
+
+#define IVHD_FLAG_HT_TUN_EN             0x00
+#define IVHD_FLAG_PASSPW_EN             0x01
+#define IVHD_FLAG_RESPASSPW_EN          0x02
+#define IVHD_FLAG_ISOC_EN               0x03
+
+#define IVMD_FLAG_EXCL_RANGE            0x08
+#define IVMD_FLAG_UNITY_MAP             0x01
+
+#define ACPI_DEVFLAG_INITPASS           0x01
+#define ACPI_DEVFLAG_EXTINT             0x02
+#define ACPI_DEVFLAG_NMI                0x04
+#define ACPI_DEVFLAG_SYSMGT1            0x10
+#define ACPI_DEVFLAG_SYSMGT2            0x20
+#define ACPI_DEVFLAG_LINT0              0x40
+#define ACPI_DEVFLAG_LINT1              0x80
+#define ACPI_DEVFLAG_ATSDIS             0x10000000
+
+/*
+ * ACPI table definitions
+ *
+ * These data structures are laid over the table to parse the important values
+ * out of it.
+ */
+
+/*
+ * structure describing one IOMMU in the ACPI table. Typically followed by one
+ * or more ivhd_entrys.
+ */
+struct ivhd_header {
+	u8 type;
+	u8 flags;
+	u16 length;
+	u16 devid;
+	u16 cap_ptr;
+	u64 mmio_phys;
+	u16 pci_seg;
+	u16 info;
+	u32 reserved;
+} __attribute__((packed));
+
+/*
+ * A device entry describing which devices a specific IOMMU translates and
+ * which requestor ids they use.
+ */
+struct ivhd_entry {
+	u8 type;
+	u16 devid;
+	u8 flags;
+	u32 ext;
+} __attribute__((packed));
+
+/*
+ * An AMD IOMMU memory definition structure. It defines things like exclusion
+ * ranges for devices and regions that should be unity mapped.
+ */
+struct ivmd_header {
+	u8 type;
+	u8 flags;
+	u16 length;
+	u16 devid;
+	u16 aux;
+	u64 resv;
+	u64 range_start;
+	u64 range_length;
+} __attribute__((packed));
+
+static int __initdata amd_iommu_detected;
+
+u16 amd_iommu_last_bdf;			/* largest PCI device id we have
+					   to handle */
+LIST_HEAD(amd_iommu_unity_map);		/* a list of required unity mappings
+					   we find in ACPI */
+unsigned amd_iommu_aperture_order = 26; /* size of aperture in power of 2 */
+int amd_iommu_isolate;			/* if 1, device isolation is enabled */
+int amd_iommu_enable = 0;		/* if 1, AMD IOMMU enabled;
+					   if 0, AMD IOMMU disabled */
+LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
+					   system */
+
+/*
+ * 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
+ * information about the domain the device belongs to as well as the
+ * page table root pointer.
+ */
+struct dev_table_entry *amd_iommu_dev_table;
+
+/*
+ * The alias table is a driver specific data structure which contains the
+ * mappings of the PCI device ids to the actual requestor ids on the IOMMU.
+ * More than one device can share the same requestor id.
+ */
+u16 *amd_iommu_alias_table;
+
+/*
+ * The rlookup table is used to find the IOMMU which is responsible
+ * for a specific device. It is also indexed by the PCI device id.
+ */
+struct amd_iommu **amd_iommu_rlookup_table;
+
+/*
+ * The pd table (protection domain table) is used to find the protection domain
+ * data structure a device belongs to. Indexed with the PCI device id too.
+ */
+struct protection_domain **amd_iommu_pd_table;
+
+/*
+ * AMD IOMMU allows up to 2^16 differend protection domains. This is a bitmap
+ * to know which ones are already in use.
+ */
+unsigned long *amd_iommu_pd_alloc_bitmap;
+
+static u32 dev_table_size;	/* size of the device table */
+static u32 alias_table_size;	/* size of the alias table */
+static u32 rlookup_table_size;	/* size if the rlookup table */
+
+static inline void update_last_devid(u16 devid)
+{
+	if (devid > amd_iommu_last_bdf)
+		amd_iommu_last_bdf = devid;
+}
+
+static inline unsigned long tbl_size(int entry_size)
+{
+	unsigned shift = PAGE_SHIFT +
+			 get_order(amd_iommu_last_bdf * entry_size);
+
+	return 1UL << shift;
+}
+
+/****************************************************************************
+ *
+ * AMD IOMMU MMIO register space handling functions
+ *
+ * These functions are used to program the IOMMU device registers in
+ * MMIO space required for that driver.
+ *
+ ****************************************************************************/
+
+/*
+ * This function set the exclusion range in the IOMMU. DMA accesses to the
+ * exclusion range are passed through untranslated
+ */
+static void __init iommu_set_exclusion_range(struct amd_iommu *iommu)
+{
+	u64 start = iommu->exclusion_start & PAGE_MASK;
+	u64 limit = (start + iommu->exclusion_length) & PAGE_MASK;
+	u64 entry;
+
+	if (!iommu->exclusion_start)
+		return;
+
+	entry = start | MMIO_EXCL_ENABLE_MASK;
+	memcpy_toio(iommu->mmio_base + MMIO_EXCL_BASE_OFFSET,
+			&entry, sizeof(entry));
+
+	entry = limit;
+	memcpy_toio(iommu->mmio_base + MMIO_EXCL_LIMIT_OFFSET,
+			&entry, sizeof(entry));
+}
+
+/* Programs the physical address of the device table into the IOMMU hardware */
+static void __init iommu_set_device_table(struct amd_iommu *iommu)
+{
+	u32 entry;
+
+	BUG_ON(iommu->mmio_base == NULL);
+
+	entry = virt_to_phys(amd_iommu_dev_table);
+	entry |= (dev_table_size >> 12) - 1;
+	memcpy_toio(iommu->mmio_base + MMIO_DEV_TABLE_OFFSET,
+			&entry, sizeof(entry));
+}
+
+/* Generic functions to enable/disable certain features of the IOMMU. */
+static void __init iommu_feature_enable(struct amd_iommu *iommu, u8 bit)
+{
+	u32 ctrl;
+
+	ctrl = readl(iommu->mmio_base + MMIO_CONTROL_OFFSET);
+	ctrl |= (1 << bit);
+	writel(ctrl, iommu->mmio_base + MMIO_CONTROL_OFFSET);
+}
+
+static void __init iommu_feature_disable(struct amd_iommu *iommu, u8 bit)
+{
+	u32 ctrl;
+
+	ctrl = (u64)readl(iommu->mmio_base + MMIO_CONTROL_OFFSET);
+	ctrl &= ~(1 << bit);
+	writel(ctrl, iommu->mmio_base + MMIO_CONTROL_OFFSET);
+}
+
+/* Function to enable the hardware */
+void __init iommu_enable(struct amd_iommu *iommu)
+{
+	printk(KERN_INFO "AMD IOMMU: Enabling IOMMU at ");
+	print_devid(iommu->devid, 0);
+	printk(" cap 0x%hx\n", iommu->cap_ptr);
+
+	iommu_feature_enable(iommu, CONTROL_IOMMU_EN);
+}
+
+/*
+ * mapping and unmapping functions for the IOMMU MMIO space. Each AMD IOMMU in
+ * the system has one.
+ */
+static u8 * __init iommu_map_mmio_space(u64 address)
+{
+	u8 *ret;
+
+	if (!request_mem_region(address, MMIO_REGION_LENGTH, "amd_iommu"))
+		return NULL;
+
+	ret = ioremap_nocache(address, MMIO_REGION_LENGTH);
+	if (ret != NULL)
+		return ret;
+
+	release_mem_region(address, MMIO_REGION_LENGTH);
+
+	return NULL;
+}
+
+static void __init iommu_unmap_mmio_space(struct amd_iommu *iommu)
+{
+	if (iommu->mmio_base)
+		iounmap(iommu->mmio_base);
+	release_mem_region(iommu->mmio_phys, MMIO_REGION_LENGTH);
+}
+
+/****************************************************************************
+ *
+ * The functions below belong to the first pass of AMD IOMMU ACPI table
+ * parsing. In this pass we try to find out the highest device id this
+ * code has to handle. Upon this information the size of the shared data
+ * structures is determined later.
+ *
+ ****************************************************************************/
+
+/*
+ * This function reads the last device id the IOMMU has to handle from the PCI
+ * capability header for this IOMMU
+ */
+static int __init find_last_devid_on_pci(int bus, int dev, int fn, int cap_ptr)
+{
+	u32 cap;
+
+	cap = read_pci_config(bus, dev, fn, cap_ptr+MMIO_RANGE_OFFSET);
+	update_last_devid(calc_devid(MMIO_GET_BUS(cap), MMIO_GET_LD(cap)));
+
+	return 0;
+}
+
+/*
+ * After reading the highest device id from the IOMMU PCI capability header
+ * this function looks if there is a higher device id defined in the ACPI table
+ */
+static int __init find_last_devid_from_ivhd(struct ivhd_header *h)
+{
+	u8 *p = (void *)h, *end = (void *)h;
+	struct ivhd_entry *dev;
+
+	p += sizeof(*h);
+	end += h->length;
+
+	find_last_devid_on_pci(PCI_BUS(h->devid),
+			PCI_SLOT(h->devid),
+			PCI_FUNC(h->devid),
+			h->cap_ptr);
+
+	while (p < end) {
+		dev = (struct ivhd_entry *)p;
+		switch (dev->type) {
+		case IVHD_DEV_SELECT:
+		case IVHD_DEV_RANGE_END:
+		case IVHD_DEV_ALIAS:
+		case IVHD_DEV_EXT_SELECT:
+			/* all the above subfield types refer to device ids */
+			update_last_devid(dev->devid);
+			break;
+		default:
+			break;
+		}
+		p += 0x04 << (*p >> 6);
+	}
+
+	WARN_ON(p != end);
+
+	return 0;
+}
+
+/*
+ * Iterate over all IVHD entries in the ACPI table and find the highest device
+ * id which we need to handle. This is the first of three functions which parse
+ * the ACPI table. So we check the checksum here.
+ */
+static int __init find_last_devid_acpi(unsigned long addr, unsigned long size)
+{
+	int i;
+	struct acpi_table_header *table = (void*)__acpi_map_table(addr, size);
+	u8 checksum = 0, *p = (u8 *)table, *end = (u8 *)table;
+	struct ivhd_header *h;
+
+	/*
+	 * Validate checksum here so we don't need to do it when
+	 * we actually parse the table
+	 */
+	for (i = 0; i < table->length; ++i)
+		checksum += p[i];
+	if (checksum != 0)
+		/* ACPI table corrupt */
+		return -ENODEV;
+
+	p += IVRS_HEADER_LENGTH;
+
+	end += table->length;
+	while (p < end) {
+		h = (struct ivhd_header *)p;
+		switch (h->type) {
+		case ACPI_IVHD_TYPE:
+			find_last_devid_from_ivhd(h);
+			break;
+		default:
+			break;
+		}
+		p += h->length;
+	}
+	WARN_ON(p != end);
+
+	printk("LastBDF: %04x\n", amd_iommu_last_bdf);
+
+	return 0;
+}
+
+/****************************************************************************
+ *
+ * The following functions belong the the code path which parses the ACPI table
+ * the second time. In this ACPI parsing iteration we allocate IOMMU specific
+ * data structures, initialize the device/alias/rlookup table and also
+ * basically initialize the hardware.
+ *
+ ****************************************************************************/
+
+/*
+ * Allocates the command buffer. This buffer is per AMD IOMMU. We can
+ * write commands to that buffer later and the IOMMU will execute them
+ * asynchronously
+ */
+static u8 * __init alloc_command_buffer(struct amd_iommu *iommu)
+{
+	u8 *cmd_buf = (u8 *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+			get_order(CMD_BUFFER_SIZE));
+	u64 entry;
+
+	if (cmd_buf == NULL)
+		return NULL;
+
+	iommu->cmd_buf_size = CMD_BUFFER_SIZE;
+
+	entry = (u64)virt_to_phys(cmd_buf);
+	entry |= MMIO_CMD_SIZE_512;
+	memcpy_toio(iommu->mmio_base + MMIO_CMD_BUF_OFFSET,
+			&entry, sizeof(entry));
+
+	iommu_feature_enable(iommu, CONTROL_CMDBUF_EN);
+
+	return cmd_buf;
+}
+
+static void __init free_command_buffer(struct amd_iommu *iommu)
+{
+	free_pages((unsigned long)iommu->cmd_buf, get_order(CMD_BUFFER_SIZE));
+}
+
+/* sets a specific bit in the device table entry. */
+static void set_dev_entry_bit(u16 devid, u8 bit)
+{
+	int i = (bit >> 5) & 0x07;
+	int _bit = bit & 0x1f;
+
+	amd_iommu_dev_table[devid].data[i] |= (1 << _bit);
+}
+
+/* Writes the specific IOMMU for a device into the rlookup table */
+static void __init set_iommu_for_device(struct amd_iommu *iommu, u16 devid)
+{
+	amd_iommu_rlookup_table[devid] = iommu;
+}
+
+/*
+ * This function takes the device specific flags read from the ACPI
+ * table and sets up the device table entry with that information
+ */
+static void __init set_dev_entry_from_acpi(struct amd_iommu *iommu,
+					   u16 devid, u32 flags, u32 ext_flags)
+{
+	if (flags & ACPI_DEVFLAG_INITPASS)
+		set_dev_entry_bit(devid, DEV_ENTRY_INIT_PASS);
+	if (flags & ACPI_DEVFLAG_EXTINT)
+		set_dev_entry_bit(devid, DEV_ENTRY_EINT_PASS);
+	if (flags & ACPI_DEVFLAG_NMI)
+		set_dev_entry_bit(devid, DEV_ENTRY_NMI_PASS);
+	if (flags & ACPI_DEVFLAG_SYSMGT1)
+		set_dev_entry_bit(devid, DEV_ENTRY_SYSMGT1);
+	if (flags & ACPI_DEVFLAG_SYSMGT2)
+		set_dev_entry_bit(devid, DEV_ENTRY_SYSMGT2);
+	if (flags & ACPI_DEVFLAG_LINT0)
+		set_dev_entry_bit(devid, DEV_ENTRY_LINT0_PASS);
+	if (flags & ACPI_DEVFLAG_LINT1)
+		set_dev_entry_bit(devid, DEV_ENTRY_LINT1_PASS);
+
+	set_iommu_for_device(iommu, devid);
+}
+
+/*
+ * Reads the device exclusion range from ACPI and initialize IOMMU with
+ * it
+ */
+static void __init set_device_exclusion_range(u16 devid, struct ivmd_header *m)
+{
+	struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];
+
+	if (!(m->flags & IVMD_FLAG_EXCL_RANGE))
+		return;
+
+	if (iommu) {
+		/*
+		 * We only can configure exclusion ranges per IOMMU, not
+		 * per device. But we can enable the exclusion range per
+		 * device. This is done here
+		 */
+		set_dev_entry_bit(m->devid, DEV_ENTRY_EX);
+		iommu->exclusion_start = m->range_start;
+		iommu->exclusion_length = m->range_length;
+	}
+}
+
+/*
+ * This function reads some important data from the IOMMU PCI space and
+ * initializes the driver data structure with it. It reads the hardware
+ * capabilities and the first/last device entries
+ */
+static void __init init_iommu_from_pci(struct amd_iommu *iommu)
+{
+	int bus = PCI_BUS(iommu->devid);
+	int dev = PCI_SLOT(iommu->devid);
+	int fn  = PCI_FUNC(iommu->devid);
+	int cap_ptr = iommu->cap_ptr;
+	u32 range;
+
+	iommu->cap = read_pci_config(bus, dev, fn, cap_ptr+MMIO_CAP_HDR_OFFSET);
+
+	range = read_pci_config(bus, dev, fn, cap_ptr+MMIO_RANGE_OFFSET);
+	iommu->first_device = calc_devid(MMIO_GET_BUS(range),
+					 MMIO_GET_FD(range));
+	iommu->last_device = calc_devid(MMIO_GET_BUS(range),
+					MMIO_GET_LD(range));
+}
+
+/*
+ * Takes a pointer to an AMD IOMMU entry in the ACPI table and
+ * initializes the hardware and our data structures with it.
+ */
+static void __init init_iommu_from_acpi(struct amd_iommu *iommu,
+					struct ivhd_header *h)
+{
+	u8 *p = (u8 *)h;
+	u8 *end = p, flags = 0;
+	u16 dev_i, devid = 0, devid_start = 0, devid_to = 0;
+	u32 ext_flags = 0;
+	int alias = 0;
+	struct ivhd_entry *e;
+
+	/*
+	 * First set the recommended feature enable bits from ACPI
+	 * into the IOMMU control registers
+	 */
+	h->flags & IVHD_FLAG_HT_TUN_EN ?
+		iommu_feature_enable(iommu, CONTROL_HT_TUN_EN) :
+		iommu_feature_disable(iommu, CONTROL_HT_TUN_EN);
+
+	h->flags & IVHD_FLAG_PASSPW_EN ?
+		iommu_feature_enable(iommu, CONTROL_PASSPW_EN) :
+		iommu_feature_disable(iommu, CONTROL_PASSPW_EN);
+
+	h->flags & IVHD_FLAG_RESPASSPW_EN ?
+		iommu_feature_enable(iommu, CONTROL_RESPASSPW_EN) :
+		iommu_feature_disable(iommu, CONTROL_RESPASSPW_EN);
+
+	h->flags & IVHD_FLAG_ISOC_EN ?
+		iommu_feature_enable(iommu, CONTROL_ISOC_EN) :
+		iommu_feature_disable(iommu, CONTROL_ISOC_EN);
+
+	/*
+	 * make IOMMU memory accesses cache coherent
+	 */
+	iommu_feature_enable(iommu, CONTROL_COHERENT_EN);
+
+	/*
+	 * Done. Now parse the device entries
+	 */
+	p += sizeof(struct ivhd_header);
+	end += h->length;
+
+	while (p < end) {
+		e = (struct ivhd_entry *)p;
+		switch (e->type) {
+		case IVHD_DEV_ALL:
+			for (dev_i = iommu->first_device;
+					dev_i <= iommu->last_device; ++dev_i)
+				set_dev_entry_from_acpi(iommu, dev_i,
+							e->flags, 0);
+			break;
+		case IVHD_DEV_SELECT:
+			devid = e->devid;
+			set_dev_entry_from_acpi(iommu, devid, e->flags, 0);
+			break;
+		case IVHD_DEV_SELECT_RANGE_START:
+			devid_start = e->devid;
+			flags = e->flags;
+			ext_flags = 0;
+			alias = 0;
+			break;
+		case IVHD_DEV_ALIAS:
+			devid = e->devid;
+			devid_to = e->ext >> 8;
+			set_dev_entry_from_acpi(iommu, devid, e->flags, 0);
+			amd_iommu_alias_table[devid] = devid_to;
+			break;
+		case IVHD_DEV_ALIAS_RANGE:
+			devid_start = e->devid;
+			flags = e->flags;
+			devid_to = e->ext >> 8;
+			ext_flags = 0;
+			alias = 1;
+			break;
+		case IVHD_DEV_EXT_SELECT:
+			devid = e->devid;
+			set_dev_entry_from_acpi(iommu, devid, e->flags,
+						e->ext);
+			break;
+		case IVHD_DEV_EXT_SELECT_RANGE:
+			devid_start = e->devid;
+			flags = e->flags;
+			ext_flags = e->ext;
+			alias = 0;
+			break;
+		case IVHD_DEV_RANGE_END:
+			devid = e->devid;
+			for (dev_i = devid_start; dev_i <= devid; ++dev_i) {
+				if (alias)
+					amd_iommu_alias_table[dev_i] = devid_to;
+				set_dev_entry_from_acpi(iommu,
+						amd_iommu_alias_table[dev_i],
+						flags, ext_flags);
+			}
+			break;
+		default:
+			break;
+		}
+
+		p += 0x04 << (e->type >> 6);
+	}
+}
+
+/* Initializes the device->iommu mapping for the driver */
+static int __init init_iommu_devices(struct amd_iommu *iommu)
+{
+	u16 i;
+
+	for (i = iommu->first_device; i <= iommu->last_device; ++i)
+		set_iommu_for_device(iommu, i);
+
+	return 0;
+}
+
+static void __init free_iommu_one(struct amd_iommu *iommu)
+{
+	free_command_buffer(iommu);
+	iommu_unmap_mmio_space(iommu);
+}
+
+static void __init free_iommu_all(void)
+{
+	struct amd_iommu *iommu, *next;
+
+	list_for_each_entry_safe(iommu, next, &amd_iommu_list, list) {
+		list_del(&iommu->list);
+		free_iommu_one(iommu);
+		kfree(iommu);
+	}
+}
+
+/*
+ * This function clues the initialization function for one IOMMU
+ * together and also allocates the command buffer and programs the
+ * hardware. It does NOT enable the IOMMU. This is done afterwards.
+ */
+static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
+{
+	spin_lock_init(&iommu->lock);
+	list_add_tail(&iommu->list, &amd_iommu_list);
+
+	/*
+	 * Copy data from ACPI table entry to the iommu struct
+	 */
+	iommu->devid = h->devid;
+	iommu->cap_ptr = h->cap_ptr;
+	iommu->mmio_phys = h->mmio_phys;
+	iommu->mmio_base = iommu_map_mmio_space(h->mmio_phys);
+	if (!iommu->mmio_base)
+		return -ENOMEM;
+
+	iommu_set_device_table(iommu);
+	iommu->cmd_buf = alloc_command_buffer(iommu);
+	if (!iommu->cmd_buf)
+		return -ENOMEM;
+
+	init_iommu_from_pci(iommu);
+	init_iommu_from_acpi(iommu, h);
+	init_iommu_devices(iommu);
+
+	return 0;
+}
+
+/*
+ * Iterates over all IOMMU entries in the ACPI table, allocates the
+ * IOMMU structure and initializes it with init_iommu_one()
+ */
+static int __init init_iommu_all(unsigned long addr, unsigned long size)
+{
+	struct acpi_table_header *table = (void*)__acpi_map_table(addr, size);
+	u8 *p = (u8 *)table, *end = (u8 *)table;
+	struct ivhd_header *h;
+	struct amd_iommu *iommu;
+	int ret;
+
+	end += table->length;
+	p += IVRS_HEADER_LENGTH;
+
+	while (p < end) {
+		h = (struct ivhd_header *)p;
+		switch (*p) {
+		case ACPI_IVHD_TYPE:
+			iommu = kzalloc(sizeof(struct amd_iommu), GFP_KERNEL);
+			if (iommu == NULL)
+				return -ENOMEM;
+			ret = init_iommu_one(iommu, h);
+			if (ret)
+				return ret;
+			break;
+		default:
+			break;
+		}
+		p += h->length;
+
+	}
+	WARN_ON(p != end);
+
+	return 0;
+}
+
+/****************************************************************************
+ *
+ * The next functions belong to the third pass of parsing the ACPI
+ * table. In this last pass the memory mapping requirements are
+ * gathered (like exclusion and unity mapping reanges).
+ *
+ ****************************************************************************/
+
+static void __init free_unity_maps(void)
+{
+	struct unity_map_entry *entry, *next;
+
+	list_for_each_entry_safe(entry, next, &amd_iommu_unity_map, list) {
+		list_del(&entry->list);
+		kfree(entry);
+	}
+}
+
+/* called when we find an exclusion range definition in ACPI */
+static int __init init_exclusion_range(struct ivmd_header *m)
+{
+	int i;
+
+	switch (m->type) {
+	case ACPI_IVMD_TYPE:
+		set_device_exclusion_range(m->devid, m);
+		break;
+	case ACPI_IVMD_TYPE_ALL:
+		for (i = 0; i <= amd_iommu_last_bdf; ++i)
+			set_device_exclusion_range(i, m);
+		break;
+	case ACPI_IVMD_TYPE_RANGE:
+		for (i = m->devid; i <= m->aux; ++i)
+			set_device_exclusion_range(i, m);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+/* called for unity map ACPI definition */
+static int __init init_unity_map_range(struct ivmd_header *m)
+{
+	struct unity_map_entry *e = 0;
+
+	e = kzalloc(sizeof(*e), GFP_KERNEL);
+	if (e == NULL)
+		return -ENOMEM;
+
+	switch (m->type) {
+	default:
+	case ACPI_IVMD_TYPE:
+		e->devid_start = e->devid_end = m->devid;
+		break;
+	case ACPI_IVMD_TYPE_ALL:
+		e->devid_start = 0;
+		e->devid_end = amd_iommu_last_bdf;
+		break;
+	case ACPI_IVMD_TYPE_RANGE:
+		e->devid_start = m->devid;
+		e->devid_end = m->aux;
+		break;
+	}
+	e->address_start = PAGE_ALIGN(m->range_start);
+	e->address_end = e->address_start + PAGE_ALIGN(m->range_length);
+	e->prot = m->flags >> 1;
+
+	list_add_tail(&e->list, &amd_iommu_unity_map);
+
+	return 0;
+}
+
+/* iterates over all memory definitions we find in the ACPI table */
+static int __init init_memory_definitions(unsigned long addr, unsigned long size)
+{
+	struct acpi_table_header *table = (void*)__acpi_map_table(addr, size);
+	u8 *p = (u8 *)table, *end = (u8 *)table;
+	struct ivmd_header *m;
+
+	end += table->length;
+	p += IVRS_HEADER_LENGTH;
+
+	while (p < end) {
+		m = (struct ivmd_header *)p;
+		if (m->flags & IVMD_FLAG_EXCL_RANGE)
+			init_exclusion_range(m);
+		else if (m->flags & IVMD_FLAG_UNITY_MAP)
+			init_unity_map_range(m);
+
+		p += m->length;
+	}
+
+	return 0;
+}
+
+/*
+ * This function finally enables all IOMMUs found in the system after
+ * they have been initialized
+ */
+static void __init enable_iommus(void)
+{
+	struct amd_iommu *iommu;
+
+	list_for_each_entry(iommu, &amd_iommu_list, list) {
+		iommu_set_exclusion_range(iommu);
+		iommu_enable(iommu);
+	}
+}
+
+/*
+ * This is the core init function for AMD IOMMU hardware in the system.
+ * This function is called from the generic x86 DMA layer initialization
+ * code.
+ *
+ * This function basically parses the ACPI table for AMD IOMMU (IVRS)
+ * three times:
+ *
+ *	1 pass) Find the highest PCI device id the driver has to handle.
+ *		Upon this information the size of the data structures is
+ *		determined that needs to be allocated.
+ *
+ *	2 pass) Initialize the data structures just allocated with the
+ *		information in the ACPI table about available AMD IOMMUs
+ *		in the system. It also maps the PCI devices in the
+ *		system to specific IOMMUs
+ *
+ *	3 pass) After the basic data structures are allocated and
+ *		initialized we update them with information about memory
+ *		remapping requirements parsed out of the ACPI table in
+ *		this last pass.
+ *
+ * After that the hardware is initialized and ready to go. In the last
+ * step we do some Linux specific things like registering the driver in
+ * the dma_ops interface and initializing the suspend/resume support
+ * functions. Finally it prints some information about AMD IOMMUs and
+ * the driver state and enables the hardware.
+ */
+int __init amd_iommu_init(void)
+{
+	int i, ret = 0;
+
+
+	if (no_iommu) {
+		printk(KERN_INFO "AMD IOMMU disabled by kernel command line\n");
+		return 0;
+	}
+
+	if (!amd_iommu_detected)
+		return -ENODEV;
+
+	/*
+	 * First parse ACPI tables to find the largest Bus/Dev/Func
+	 * we need to handle. Upon this information the shared data
+	 * structures for the IOMMUs in the system will be allocated
+	 */
+	if (acpi_table_parse(ACPI_IVRS, find_last_devid_acpi) == 0)
+		return -ENODEV;
+
+	dev_table_size     = tbl_size(DEV_TABLE_ENTRY_SIZE);
+	alias_table_size   = tbl_size(ALIAS_TABLE_ENTRY_SIZE);
+	rlookup_table_size = tbl_size(RLOOKUP_TABLE_ENTRY_SIZE);
+
+	ret = -ENOMEM;
+
+	/* Device table - directly used by all IOMMUs */
+	amd_iommu_dev_table = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+				      get_order(dev_table_size));
+	if (amd_iommu_dev_table == NULL)
+		goto out;
+
+	/*
+	 * Alias table - map PCI Bus/Dev/Func to Bus/Dev/Func the
+	 * IOMMU see for that device
+	 */
+	amd_iommu_alias_table = (void *)__get_free_pages(GFP_KERNEL,
+			get_order(alias_table_size));
+	if (amd_iommu_alias_table == NULL)
+		goto free;
+
+	/* IOMMU rlookup table - find the IOMMU for a specific device */
+	amd_iommu_rlookup_table = (void *)__get_free_pages(GFP_KERNEL,
+			get_order(rlookup_table_size));
+	if (amd_iommu_rlookup_table == NULL)
+		goto free;
+
+	/*
+	 * Protection Domain table - maps devices to protection domains
+	 * This table has the same size as the rlookup_table
+	 */
+	amd_iommu_pd_table = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+				     get_order(rlookup_table_size));
+	if (amd_iommu_pd_table == NULL)
+		goto free;
+
+	amd_iommu_pd_alloc_bitmap = (void *)__get_free_pages(
+					    GFP_KERNEL | __GFP_ZERO,
+					    get_order(MAX_DOMAIN_ID/8));
+	if (amd_iommu_pd_alloc_bitmap == NULL)
+		goto free;
+
+	/*
+	 * let all alias entries point to itself
+	 */
+	for (i = 0; i <= amd_iommu_last_bdf; ++i)
+		amd_iommu_alias_table[i] = i;
+
+	/*
+	 * never allocate domain 0 because its used as the non-allocated and
+	 * error value placeholder
+	 */
+	amd_iommu_pd_alloc_bitmap[0] = 1;
+
+	/*
+	 * now the data structures are allocated and basically initialized
+	 * start the real acpi table scan
+	 */
+	ret = -ENODEV;
+	if (acpi_table_parse(ACPI_IVRS, init_iommu_all) == 0)
+		goto free;
+
+	if (acpi_table_parse(ACPI_IVRS, init_memory_definitions) == 0)
+		goto free;
+
+	ret = amd_iommu_init_dma_ops();
+	if (ret)
+		goto free;
+
+	enable_iommus();
+
+	printk(KERN_INFO "AMD IOMMU: aperture size is %d MB\n",
+			(1 << (amd_iommu_aperture_order-20)));
+
+	printk(KERN_INFO "AMD IOMMU: device isolation ");
+	if (amd_iommu_isolate)
+		printk("enabled\n");
+	else
+		printk("disabled\n");
+
+out:
+	return ret;
+
+free:
+
+	free_pages((unsigned long)amd_iommu_pd_alloc_bitmap, 1);
+
+	free_pages((unsigned long)amd_iommu_pd_table,
+		   get_order(rlookup_table_size));
+
+	free_pages((unsigned long)amd_iommu_rlookup_table,
+		   get_order(rlookup_table_size));
+
+	free_pages((unsigned long)amd_iommu_alias_table,
+		   get_order(alias_table_size));
+
+	free_pages((unsigned long)amd_iommu_dev_table,
+		   get_order(dev_table_size));
+
+	free_iommu_all();
+
+	free_unity_maps();
+
+	goto out;
+}
+
+/****************************************************************************
+ *
+ * Early detect code. This code runs at IOMMU detection time in the DMA
+ * layer. It just looks if there is an IVRS ACPI table to detect AMD
+ * IOMMUs
+ *
+ ****************************************************************************/
+static int __init early_amd_iommu_detect(unsigned long phys_addr, unsigned long size)
+{
+	return 0;
+}
+
+void __init amd_iommu_detect(void)
+{
+	if (swiotlb || no_iommu || (iommu_detected && !iommu_aperture))
+		return;
+
+	if (amd_iommu_enable == 0)
+		return;
+
+	if (acpi_table_parse(ACPI_IVRS, early_amd_iommu_detect) != 0) {
+		iommu_detected = 1;
+		amd_iommu_detected = 1;
+#ifdef CONFIG_IOMMU
+		iommu_aperture_disabled = 1;
+		iommu_aperture = 0;
+#endif
+	}
+}
+
+/****************************************************************************
+ *
+ * Parsing functions for the AMD IOMMU specific kernel command line
+ * options.
+ *
+ ****************************************************************************/
+
+static int __init parse_amd_iommu_options(char *str)
+{
+	for (; *str; ++str) {
+		if (strcmp(str, "isolate") == 0)
+			amd_iommu_isolate = 1;
+	}
+
+	return 1;
+}
+
+static int __init parse_amd_iommu_size_options(char *str)
+{
+	unsigned order = PAGE_SHIFT + get_order(memparse(str, &str));
+
+	if ((order > 24) && (order < 31))
+		amd_iommu_aperture_order = order;
+
+	return 1;
+}
+
+__setup("amd_iommu=", parse_amd_iommu_options);
+__setup("amd_iommu_size=", parse_amd_iommu_size_options);
diff --git a/arch/x86_64/kernel/pci-dma.c b/arch/x86_64/kernel/pci-dma.c
index 4f2915e..ce9d13e 100644
--- a/arch/x86_64/kernel/pci-dma.c
+++ b/arch/x86_64/kernel/pci-dma.c
@@ -10,6 +10,8 @@
 #include <asm/io.h>
 #include <asm/proto.h>
 #include <asm/calgary.h>
+#include <asm/amd_iommu.h>
+#include <asm/amd_iommu_types.h>
 
 int iommu_merge __read_mostly = 0;
 EXPORT_SYMBOL(iommu_merge);
@@ -279,6 +281,11 @@ __init int iommu_setup(char *p)
 		    use_calgary = 1;
 #endif /* CONFIG_CALGARY_IOMMU */
 
+#ifdef CONFIG_AMD_IOMMU
+	    if (!strncmp(p, "amd", 3))
+		    amd_iommu_enable = 1;
+#endif /* CONFIG_AMD_IOMMU */
+
 	    p += strcspn(p, ",");
 	    if (*p == ',')
 		    ++p;
@@ -301,6 +308,10 @@ void __init pci_iommu_alloc(void)
 	detect_calgary();
 #endif
 
+#ifdef CONFIG_AMD_IOMMU
+	amd_iommu_detect();
+#endif
+
 #ifdef CONFIG_SWIOTLB
 	pci_swiotlb_init();
 #endif
@@ -312,6 +323,10 @@ static int __init pci_iommu_init(void)
 	calgary_iommu_init();
 #endif
 
+#ifdef CONFIG_AMD_IOMMU
+	amd_iommu_init();
+#endif
+
 #ifdef CONFIG_IOMMU
 	gart_iommu_init();
 #endif
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index bfb3bfc..6658212 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -58,6 +58,7 @@ static char *acpi_table_signatures[ACPI_TABLE_COUNT] = {
 	[ACPI_SPMI] = "SPMI",
 	[ACPI_HPET] = "HPET",
 	[ACPI_MCFG] = "MCFG",
+	[ACPI_IVRS] = "IVRS",
 };
 
 static char *mps_inti_flags_polarity[] = { "dfl", "high", "res", "low" };
diff --git a/include/asm-x86_64/amd_iommu.h b/include/asm-x86_64/amd_iommu.h
new file mode 100644
index 0000000..783f43e
--- /dev/null
+++ b/include/asm-x86_64/amd_iommu.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
+ * Author: Joerg Roedel <joerg.roedel@amd.com>
+ *         Leo Duran <leo.duran@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#ifndef ASM_X86__AMD_IOMMU_H
+#define ASM_X86__AMD_IOMMU_H
+
+#ifdef CONFIG_AMD_IOMMU
+extern int amd_iommu_init(void);
+extern int amd_iommu_init_dma_ops(void);
+extern void amd_iommu_detect(void);
+#else
+static inline int amd_iommu_init(void) { return -ENODEV; }
+static inline void amd_iommu_detect(void) { }
+#endif
+
+#endif /* ASM_X86__AMD_IOMMU_H */
diff --git a/include/asm-x86_64/amd_iommu_types.h b/include/asm-x86_64/amd_iommu_types.h
new file mode 100644
index 0000000..3a8c58c
--- /dev/null
+++ b/include/asm-x86_64/amd_iommu_types.h
@@ -0,0 +1,347 @@
+/*
+ * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
+ * Author: Joerg Roedel <joerg.roedel@amd.com>
+ *         Leo Duran <leo.duran@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#ifndef ASM_X86__AMD_IOMMU_TYPES_H
+#define ASM_X86__AMD_IOMMU_TYPES_H
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
+/*
+ * some size calculation constants
+ */
+#define DEV_TABLE_ENTRY_SIZE		32
+#define ALIAS_TABLE_ENTRY_SIZE		2
+#define RLOOKUP_TABLE_ENTRY_SIZE	(sizeof(void *))
+
+/* helper macros */
+#define LOW_U32(x) ((u32)(x))
+#define HIGH_U32(x) ((u32)((x) >> 32))
+
+/* Length of the MMIO region for the AMD IOMMU */
+#define MMIO_REGION_LENGTH       0x4000
+
+/* Capability offsets used by the driver */
+#define MMIO_CAP_HDR_OFFSET	0x00
+#define MMIO_RANGE_OFFSET	0x0c
+
+/* Masks, shifts and macros to parse the device range capability */
+#define MMIO_RANGE_LD_MASK	0xff000000
+#define MMIO_RANGE_FD_MASK	0x00ff0000
+#define MMIO_RANGE_BUS_MASK	0x0000ff00
+#define MMIO_RANGE_LD_SHIFT	24
+#define MMIO_RANGE_FD_SHIFT	16
+#define MMIO_RANGE_BUS_SHIFT	8
+#define MMIO_GET_LD(x)  (((x) & MMIO_RANGE_LD_MASK) >> MMIO_RANGE_LD_SHIFT)
+#define MMIO_GET_FD(x)  (((x) & MMIO_RANGE_FD_MASK) >> MMIO_RANGE_FD_SHIFT)
+#define MMIO_GET_BUS(x) (((x) & MMIO_RANGE_BUS_MASK) >> MMIO_RANGE_BUS_SHIFT)
+
+/* Flag masks for the AMD IOMMU exclusion range */
+#define MMIO_EXCL_ENABLE_MASK 0x01ULL
+#define MMIO_EXCL_ALLOW_MASK  0x02ULL
+
+/* Used offsets into the MMIO space */
+#define MMIO_DEV_TABLE_OFFSET   0x0000
+#define MMIO_CMD_BUF_OFFSET     0x0008
+#define MMIO_EVT_BUF_OFFSET     0x0010
+#define MMIO_CONTROL_OFFSET     0x0018
+#define MMIO_EXCL_BASE_OFFSET   0x0020
+#define MMIO_EXCL_LIMIT_OFFSET  0x0028
+#define MMIO_CMD_HEAD_OFFSET	0x2000
+#define MMIO_CMD_TAIL_OFFSET	0x2008
+#define MMIO_EVT_HEAD_OFFSET	0x2010
+#define MMIO_EVT_TAIL_OFFSET	0x2018
+#define MMIO_STATUS_OFFSET	0x2020
+
+#define IOMMU_STATUS_COMWAITINT_MASK	0x04
+
+/* feature control bits */
+#define CONTROL_IOMMU_EN        0x00ULL
+#define CONTROL_HT_TUN_EN       0x01ULL
+#define CONTROL_EVT_LOG_EN      0x02ULL
+#define CONTROL_EVT_INT_EN      0x03ULL
+#define CONTROL_COMWAIT_EN      0x04ULL
+#define CONTROL_PASSPW_EN       0x08ULL
+#define CONTROL_RESPASSPW_EN    0x09ULL
+#define CONTROL_COHERENT_EN     0x0aULL
+#define CONTROL_ISOC_EN         0x0bULL
+#define CONTROL_CMDBUF_EN       0x0cULL
+#define CONTROL_PPFLOG_EN       0x0dULL
+#define CONTROL_PPFINT_EN       0x0eULL
+
+/* command specific defines */
+#define CMD_COMPL_WAIT          0x01
+#define CMD_INV_DEV_ENTRY       0x02
+#define CMD_INV_IOMMU_PAGES     0x03
+
+#define CMD_COMPL_WAIT_STORE_MASK	0x01
+#define CMD_COMPL_WAIT_INT_MASK		0x02
+#define CMD_INV_IOMMU_PAGES_SIZE_MASK	0x01
+#define CMD_INV_IOMMU_PAGES_PDE_MASK	0x02
+
+#define CMD_INV_IOMMU_ALL_PAGES_ADDRESS	0x7fffffffffffffffULL
+
+/* macros and definitions for device table entries */
+#define DEV_ENTRY_VALID         0x00
+#define DEV_ENTRY_TRANSLATION   0x01
+#define DEV_ENTRY_IR            0x3d
+#define DEV_ENTRY_IW            0x3e
+#define DEV_ENTRY_EX            0x67
+#define DEV_ENTRY_SYSMGT1       0x68
+#define DEV_ENTRY_SYSMGT2       0x69
+#define DEV_ENTRY_INIT_PASS     0xb8
+#define DEV_ENTRY_EINT_PASS     0xb9
+#define DEV_ENTRY_NMI_PASS      0xba
+#define DEV_ENTRY_LINT0_PASS    0xbe
+#define DEV_ENTRY_LINT1_PASS    0xbf
+
+/* constants to configure the command buffer */
+#define CMD_BUFFER_SIZE    8192
+#define CMD_BUFFER_ENTRIES 512
+#define MMIO_CMD_SIZE_SHIFT 56
+#define MMIO_CMD_SIZE_512 (0x9ULL << MMIO_CMD_SIZE_SHIFT)
+
+#define PAGE_MODE_1_LEVEL 0x01
+#define PAGE_MODE_2_LEVEL 0x02
+#define PAGE_MODE_3_LEVEL 0x03
+
+#define IOMMU_PDE_NL_0   0x000ULL
+#define IOMMU_PDE_NL_1   0x200ULL
+#define IOMMU_PDE_NL_2   0x400ULL
+#define IOMMU_PDE_NL_3   0x600ULL
+
+#define IOMMU_PTE_L2_INDEX(address) (((address) >> 30) & 0x1ffULL)
+#define IOMMU_PTE_L1_INDEX(address) (((address) >> 21) & 0x1ffULL)
+#define IOMMU_PTE_L0_INDEX(address) (((address) >> 12) & 0x1ffULL)
+
+#define IOMMU_MAP_SIZE_L1 (1ULL << 21)
+#define IOMMU_MAP_SIZE_L2 (1ULL << 30)
+#define IOMMU_MAP_SIZE_L3 (1ULL << 39)
+
+#define IOMMU_PTE_P  (1ULL << 0)
+#define IOMMU_PTE_U  (1ULL << 59)
+#define IOMMU_PTE_FC (1ULL << 60)
+#define IOMMU_PTE_IR (1ULL << 61)
+#define IOMMU_PTE_IW (1ULL << 62)
+
+#define IOMMU_L1_PDE(address) \
+	((address) | IOMMU_PDE_NL_1 | IOMMU_PTE_P | IOMMU_PTE_IR | IOMMU_PTE_IW)
+#define IOMMU_L2_PDE(address) \
+	((address) | IOMMU_PDE_NL_2 | IOMMU_PTE_P | IOMMU_PTE_IR | IOMMU_PTE_IW)
+
+#define IOMMU_PAGE_MASK (((1ULL << 52) - 1) & ~0xfffULL)
+#define IOMMU_PTE_PRESENT(pte) ((pte) & IOMMU_PTE_P)
+#define IOMMU_PTE_PAGE(pte) (phys_to_virt((pte) & IOMMU_PAGE_MASK))
+#define IOMMU_PTE_MODE(pte) (((pte) >> 9) & 0x07)
+
+#define IOMMU_PROT_MASK 0x03
+#define IOMMU_PROT_IR 0x01
+#define IOMMU_PROT_IW 0x02
+
+/* IOMMU capabilities */
+#define IOMMU_CAP_IOTLB   24
+#define IOMMU_CAP_NPCACHE 26
+
+#define MAX_DOMAIN_ID 65536
+
+/*
+ * This structure contains generic data for  IOMMU protection domains
+ * independent of their use.
+ */
+struct protection_domain {
+	spinlock_t lock; /* mostly used to lock the page table*/
+	u16 id;		 /* the domain id written to the device table */
+	int mode;	 /* paging mode (0-6 levels) */
+	u64 *pt_root;	 /* page table root pointer */
+	void *priv;	 /* private data */
+};
+
+/*
+ * Data container for a dma_ops specific protection domain
+ */
+struct dma_ops_domain {
+	struct list_head list;
+
+	/* generic protection domain information */
+	struct protection_domain domain;
+
+	/* size of the aperture for the mappings */
+	unsigned long aperture_size;
+
+	/* address we start to search for free addresses */
+	unsigned long next_bit;
+
+	/* address allocation bitmap */
+	unsigned long *bitmap;
+
+	/*
+	 * Array of PTE pages for the aperture. In this array we save all the
+	 * leaf pages of the domain page table used for the aperture. This way
+	 * we don't need to walk the page table to find a specific PTE. We can
+	 * just calculate its address in constant time.
+	 */
+	u64 **pte_pages;
+};
+
+/*
+ * Structure where we save information about one hardware AMD IOMMU in the
+ * system.
+ */
+struct amd_iommu {
+	struct list_head list;
+
+	/* locks the accesses to the hardware */
+	spinlock_t lock;
+
+	/* device id of this IOMMU */
+	u16 devid;
+	/*
+	 * Capability pointer. There could be more than one IOMMU per PCI
+	 * device function if there are more than one AMD IOMMU capability
+	 * pointers.
+	 */
+	u16 cap_ptr;
+
+	/* physical address of MMIO space */
+	u64 mmio_phys;
+	/* virtual address of MMIO space */
+	u8 *mmio_base;
+
+	/* capabilities of that IOMMU read from ACPI */
+	u32 cap;
+
+	/* first device this IOMMU handles. read from PCI */
+	u16 first_device;
+	/* last device this IOMMU handles. read from PCI */
+	u16 last_device;
+
+	/* start of exclusion range of that IOMMU */
+	u64 exclusion_start;
+	/* length of exclusion range of that IOMMU */
+	u64 exclusion_length;
+
+	/* command buffer virtual address */
+	u8 *cmd_buf;
+	/* size of command buffer */
+	u32 cmd_buf_size;
+
+	/* if one, we need to send a completion wait command */
+	int need_sync;
+
+	/* default dma_ops domain for that IOMMU */
+	struct dma_ops_domain *default_dom;
+};
+
+/*
+ * List with all IOMMUs in the system. This list is not locked because it is
+ * only written and read at driver initialization or suspend time
+ */
+extern struct list_head amd_iommu_list;
+
+/*
+ * Structure defining one entry in the device table
+ */
+struct dev_table_entry {
+	u32 data[8];
+};
+
+/*
+ * One entry for unity mappings parsed out of the ACPI table.
+ */
+struct unity_map_entry {
+	struct list_head list;
+
+	/* starting device id this entry is used for (including) */
+	u16 devid_start;
+	/* end device id this entry is used for (including) */
+	u16 devid_end;
+
+	/* start address to unity map (including) */
+	u64 address_start;
+	/* end address to unity map (including) */
+	u64 address_end;
+
+	/* required protection */
+	int prot;
+};
+
+/*
+ * List of all unity mappings. It is not locked because as runtime it is only
+ * read. It is created at ACPI table parsing time.
+ */
+extern struct list_head amd_iommu_unity_map;
+
+/*
+ * Data structures for device handling
+ */
+
+/*
+ * Device table used by hardware. Read and write accesses by software are
+ * locked with the amd_iommu_pd_table lock.
+ */
+extern struct dev_table_entry *amd_iommu_dev_table;
+
+/*
+ * Alias table to find requestor ids to device ids. Not locked because only
+ * read on runtime.
+ */
+extern u16 *amd_iommu_alias_table;
+
+/*
+ * Reverse lookup table to find the IOMMU which translates a specific device.
+ */
+extern struct amd_iommu **amd_iommu_rlookup_table;
+
+/* size of the dma_ops aperture as power of 2 */
+extern unsigned amd_iommu_aperture_order;
+
+/* largest PCI device id we expect translation requests for */
+extern u16 amd_iommu_last_bdf;
+
+/* data structures for protection domain handling */
+extern struct protection_domain **amd_iommu_pd_table;
+
+/* allocation bitmap for domain ids */
+extern unsigned long *amd_iommu_pd_alloc_bitmap;
+
+/* will be 1 if device isolation is enabled */
+extern int amd_iommu_isolate;
+extern int amd_iommu_enable;
+
+/* takes a PCI device id and prints it out in a readable form */
+static inline void print_devid(u16 devid, int nl)
+{
+	int bus = devid >> 8;
+	int dev = devid >> 3 & 0x1f;
+	int fn  = devid & 0x07;
+
+	printk("%02x:%02x.%x", bus, dev, fn);
+	if (nl)
+		printk("\n");
+}
+
+/* takes bus and device/function and returns the device id
+ * FIXME: should that be in generic PCI code? */
+static inline u16 calc_devid(u8 bus, u8 devfn)
+{
+	return (((u16)bus) << 8) | devfn;
+}
+
+#endif /* ASM_X86__AMD_IOMMU_TYPES_H */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index ba8cacf..abeaf47 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -383,6 +383,7 @@ enum acpi_table_id {
 	ACPI_SPMI,
 	ACPI_HPET,
 	ACPI_MCFG,
+	ACPI_IVRS,
 	ACPI_TABLE_COUNT
 };
 
diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index c975caf..f8598f5 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -8,3 +8,4 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
 				      unsigned long align_mask);
 extern void iommu_area_free(unsigned long *map, unsigned long start,
 			    unsigned int nr);
+extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len);
diff --git a/lib/Makefile b/lib/Makefile
index 1469913..7d85f21 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -56,7 +56,7 @@ obj-$(CONFIG_SMP) += percpu_counter.o
 obj-$(CONFIG_AUDIT_GENERIC) += audit.o
 
 obj-$(CONFIG_SWIOTLB) += swiotlb.o
-obj-$(CONFIG_IOMMU) += iommu-helper.o
+obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
 
 ifeq ($(CONFIG_X86),y)
 swiotlb-$(CONFIG_XEN) := ../arch/i386/kernel/swiotlb.o
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index e0c0e76..90a9cc8 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -79,3 +79,11 @@ void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
 	}
 }
 EXPORT_SYMBOL(iommu_area_free);
+
+unsigned long iommu_num_pages(unsigned long addr, unsigned long len)
+{
+	unsigned long size = roundup((addr & ~PAGE_MASK) + len, PAGE_SIZE);
+
+	return size >> PAGE_SHIFT;
+}
+EXPORT_SYMBOL(iommu_num_pages);