arch/x86/kernel/pci-dma.c - linux - Git at Google

 #include <linux/dma-mapping.h>
 #include <linux/dma-debug.h>
 #include <linux/dmar.h>
 #include <linux/export.h>
 #include <linux/bootmem.h>
 #include <linux/gfp.h>
 #include <linux/pci.h>
 #include <linux/kmemleak.h>

 #include <asm/proto.h>
 #include <asm/dma.h>
 #include <asm/iommu.h>
 #include <asm/gart.h>
 #include <asm/calgary.h>
 #include <asm/x86_init.h>
 #include <asm/iommu_table.h>

 static int forbid_dac __read_mostly;

 struct dma_map_ops *dma_ops = &nommu_dma_ops;
 EXPORT_SYMBOL(dma_ops);

 static int iommu_sac_force __read_mostly;

 #ifdef CONFIG_IOMMU_DEBUG
 int panic_on_overflow __read_mostly = 1;
 int force_iommu __read_mostly = 1;
 #else
 int panic_on_overflow __read_mostly = 0;
 int force_iommu __read_mostly = 0;
 #endif

 int iommu_merge __read_mostly = 0;

 int no_iommu __read_mostly;
 /* Set this to 1 if there is a HW IOMMU in the system */
 int iommu_detected __read_mostly = 0;

 /*
  * This variable becomes 1 if iommu=pt is passed on the kernel command line.
  * If this variable is 1, IOMMU implementations do no DMA translation for
  * devices and allow every device to access to whole physical memory. This is
  * useful if a user wants to use an IOMMU only for KVM device assignment to
  * guests and not for driver dma translation.
  */
 int iommu_pass_through __read_mostly;

 extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];

 /* Dummy device used for NULL arguments (normally ISA). */
 struct device x86_dma_fallback_dev = {
 	.init_name = "fallback device",
 	.coherent_dma_mask = ISA_DMA_BIT_MASK,
 	.dma_mask = &x86_dma_fallback_dev.coherent_dma_mask,
 };
 EXPORT_SYMBOL(x86_dma_fallback_dev);

 /* Number of entries preallocated for DMA-API debugging */
 #define PREALLOC_DMA_DEBUG_ENTRIES       65536

 void __init pci_iommu_alloc(void)
 {
 	struct iommu_table_entry *p;

 	sort_iommu_table(__iommu_table, __iommu_table_end);
 	check_iommu_entries(__iommu_table, __iommu_table_end);

 	for (p = __iommu_table; p < __iommu_table_end; p++) {
 		if (p && p->detect && p->detect() > 0) {
 			p->flags |= IOMMU_DETECTED;
 			if (p->early_init)
 				p->early_init();
 			if (p->flags & IOMMU_FINISH_IF_DETECTED)
 				break;
 		}
 	}
 }
 void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 				 dma_addr_t *dma_addr, gfp_t flag,
 				 unsigned long attrs)
 {
 	unsigned long dma_mask;
 	struct page *page;
 	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	dma_addr_t addr;

 	dma_mask = dma_alloc_coherent_mask(dev, flag);

 	flag &= ~__GFP_ZERO;
 again:
 	page = NULL;
 	/* CMA can be used only in the context which permits sleeping */
 	if (gfpflags_allow_blocking(flag)) {
 		page = dma_alloc_from_contiguous(dev, count, get_order(size));
 		if (page && page_to_phys(page) + size > dma_mask) {
 			dma_release_from_contiguous(dev, page, count);
 			page = NULL;
 		}
 	}
 	/* fallback */
 	if (!page)
 		page = alloc_pages_node(dev_to_node(dev), flag, get_order(size));
 	if (!page)
 		return NULL;

 	addr = page_to_phys(page);
 	if (addr + size > dma_mask) {
 		__free_pages(page, get_order(size));

 		if (dma_mask < DMA_BIT_MASK(32) && !(flag & GFP_DMA)) {
 			flag = (flag & ~GFP_DMA32) | GFP_DMA;
 			goto again;
 		}

 		return NULL;
 	}
 	memset(page_address(page), 0, size);
 	*dma_addr = addr;
 	return page_address(page);
 }

 void dma_generic_free_coherent(struct device *dev, size_t size, void *vaddr,
 			       dma_addr_t dma_addr, unsigned long attrs)
 {
 	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	struct page *page = virt_to_page(vaddr);

 	if (!dma_release_from_contiguous(dev, page, count))
 		free_pages((unsigned long)vaddr, get_order(size));
 }

 bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp)
 {
 	if (!*dev)
 		*dev = &x86_dma_fallback_dev;

 	*gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
 	*gfp = dma_alloc_coherent_gfp_flags(*dev, *gfp);

 	if (!is_device_dma_capable(*dev))
 		return false;
 	return true;

 }
 EXPORT_SYMBOL(arch_dma_alloc_attrs);

 /*
  * See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
  * parameter documentation.
  */
 static __init int iommu_setup(char *p)
 {
 	iommu_merge = 1;

 	if (!p)
 		return -EINVAL;

 	while (*p) {
 		if (!strncmp(p, "off", 3))
 			no_iommu = 1;
 		/* gart_parse_options has more force support */
 		if (!strncmp(p, "force", 5))
 			force_iommu = 1;
 		if (!strncmp(p, "noforce", 7)) {
 			iommu_merge = 0;
 			force_iommu = 0;
 		}

 		if (!strncmp(p, "biomerge", 8)) {
 			iommu_merge = 1;
 			force_iommu = 1;
 		}
 		if (!strncmp(p, "panic", 5))
 			panic_on_overflow = 1;
 		if (!strncmp(p, "nopanic", 7))
 			panic_on_overflow = 0;
 		if (!strncmp(p, "merge", 5)) {
 			iommu_merge = 1;
 			force_iommu = 1;
 		}
 		if (!strncmp(p, "nomerge", 7))
 			iommu_merge = 0;
 		if (!strncmp(p, "forcesac", 8))
 			iommu_sac_force = 1;
 		if (!strncmp(p, "allowdac", 8))
 			forbid_dac = 0;
 		if (!strncmp(p, "nodac", 5))
 			forbid_dac = 1;
 		if (!strncmp(p, "usedac", 6)) {
 			forbid_dac = -1;
 			return 1;
 		}
 #ifdef CONFIG_SWIOTLB
 		if (!strncmp(p, "soft", 4))
 			swiotlb = 1;
 #endif
 		if (!strncmp(p, "pt", 2))
 			iommu_pass_through = 1;

 		gart_parse_options(p);

 #ifdef CONFIG_CALGARY_IOMMU
 		if (!strncmp(p, "calgary", 7))
 			use_calgary = 1;
 #endif /* CONFIG_CALGARY_IOMMU */

 		p += strcspn(p, ",");
 		if (*p == ',')
 			++p;
 	}
 	return 0;
 }
 early_param("iommu", iommu_setup);

 int dma_supported(struct device *dev, u64 mask)
 {
 	struct dma_map_ops *ops = get_dma_ops(dev);

 #ifdef CONFIG_PCI
 	if (mask > 0xffffffff && forbid_dac > 0) {
 		dev_info(dev, "PCI: Disallowing DAC for device\n");
 		return 0;
 	}
 #endif

 	if (ops->dma_supported)
 		return ops->dma_supported(dev, mask);

 	/* Copied from i386. Doesn't make much sense, because it will
 	   only work for pci_alloc_coherent.
 	   The caller just has to use GFP_DMA in this case. */
 	if (mask < DMA_BIT_MASK(24))
 		return 0;

 	/* Tell the device to use SAC when IOMMU force is on.  This
 	   allows the driver to use cheaper accesses in some cases.

 	   Problem with this is that if we overflow the IOMMU area and
 	   return DAC as fallback address the device may not handle it
 	   correctly.

 	   As a special case some controllers have a 39bit address
 	   mode that is as efficient as 32bit (aic79xx). Don't force
 	   SAC for these.  Assume all masks <= 40 bits are of this
 	   type. Normally this doesn't make any difference, but gives
 	   more gentle handling of IOMMU overflow. */
 	if (iommu_sac_force && (mask >= DMA_BIT_MASK(40))) {
 		dev_info(dev, "Force SAC with mask %Lx\n", mask);
 		return 0;
 	}

 	return 1;
 }
 EXPORT_SYMBOL(dma_supported);

 static int __init pci_iommu_init(void)
 {
 	struct iommu_table_entry *p;
 	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);

 #ifdef CONFIG_PCI
 	dma_debug_add_bus(&pci_bus_type);
 #endif
 	x86_init.iommu.iommu_init();

 	for (p = __iommu_table; p < __iommu_table_end; p++) {
 		if (p && (p->flags & IOMMU_DETECTED) && p->late_init)
 			p->late_init();
 	}

 	return 0;
 }
 /* Must execute after PCI subsystem */
 rootfs_initcall(pci_iommu_init);

 #ifdef CONFIG_PCI
 /* Many VIA bridges seem to corrupt data for DAC. Disable it here */

 static void via_no_dac(struct pci_dev *dev)
 {
 	if (forbid_dac == 0) {
 		dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
 		forbid_dac = 1;
 	}
 }
 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
 				PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);
 #endif
	#include <linux/dma-mapping.h>
	#include <linux/dma-debug.h>
	#include <linux/dmar.h>
	#include <linux/export.h>
	#include <linux/bootmem.h>
	#include <linux/gfp.h>
	#include <linux/pci.h>
	#include <linux/kmemleak.h>

	#include <asm/proto.h>
	#include <asm/dma.h>
	#include <asm/iommu.h>
	#include <asm/gart.h>
	#include <asm/calgary.h>
	#include <asm/x86_init.h>
	#include <asm/iommu_table.h>

	static int forbid_dac __read_mostly;

	struct dma_map_ops *dma_ops = &nommu_dma_ops;
	EXPORT_SYMBOL(dma_ops);

	static int iommu_sac_force __read_mostly;

	#ifdef CONFIG_IOMMU_DEBUG
	int panic_on_overflow __read_mostly = 1;
	int force_iommu __read_mostly = 1;
	#else
	int panic_on_overflow __read_mostly = 0;
	int force_iommu __read_mostly = 0;
	#endif

	int iommu_merge __read_mostly = 0;

	int no_iommu __read_mostly;
	/* Set this to 1 if there is a HW IOMMU in the system */
	int iommu_detected __read_mostly = 0;

	/*
	* This variable becomes 1 if iommu=pt is passed on the kernel command line.
	* If this variable is 1, IOMMU implementations do no DMA translation for
	* devices and allow every device to access to whole physical memory. This is
	* useful if a user wants to use an IOMMU only for KVM device assignment to
	* guests and not for driver dma translation.
	*/
	int iommu_pass_through __read_mostly;

	extern struct iommu_table_entry __iommu_table[], __iommu_table_end[];

	/* Dummy device used for NULL arguments (normally ISA). */
	struct device x86_dma_fallback_dev = {
	.init_name = "fallback device",
	.coherent_dma_mask = ISA_DMA_BIT_MASK,
	.dma_mask = &x86_dma_fallback_dev.coherent_dma_mask,
	};
	EXPORT_SYMBOL(x86_dma_fallback_dev);

	/* Number of entries preallocated for DMA-API debugging */
	#define PREALLOC_DMA_DEBUG_ENTRIES 65536

	void __init pci_iommu_alloc(void)
	{
	struct iommu_table_entry *p;

	sort_iommu_table(__iommu_table, __iommu_table_end);
	check_iommu_entries(__iommu_table, __iommu_table_end);

	for (p = __iommu_table; p < __iommu_table_end; p++) {
	if (p && p->detect && p->detect() > 0) {
	p->flags \|= IOMMU_DETECTED;
	if (p->early_init)
	p->early_init();
	if (p->flags & IOMMU_FINISH_IF_DETECTED)
	break;
	}
	}
	}
	void dma_generic_alloc_coherent(struct device dev, size_t size,
	dma_addr_t *dma_addr, gfp_t flag,
	unsigned long attrs)
	{
	unsigned long dma_mask;
	struct page *page;
	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
	dma_addr_t addr;

	dma_mask = dma_alloc_coherent_mask(dev, flag);

	flag &= ~__GFP_ZERO;
	again:
	page = NULL;
	/* CMA can be used only in the context which permits sleeping */
	if (gfpflags_allow_blocking(flag)) {
	page = dma_alloc_from_contiguous(dev, count, get_order(size));
	if (page && page_to_phys(page) + size > dma_mask) {
	dma_release_from_contiguous(dev, page, count);
	page = NULL;
	}
	}
	/* fallback */
	if (!page)
	page = alloc_pages_node(dev_to_node(dev), flag, get_order(size));
	if (!page)
	return NULL;

	addr = page_to_phys(page);
	if (addr + size > dma_mask) {
	__free_pages(page, get_order(size));

	if (dma_mask < DMA_BIT_MASK(32) && !(flag & GFP_DMA)) {
	flag = (flag & ~GFP_DMA32) \| GFP_DMA;
	goto again;
	}

	return NULL;
	}
	memset(page_address(page), 0, size);
	*dma_addr = addr;
	return page_address(page);
	}

	void dma_generic_free_coherent(struct device dev, size_t size, void vaddr,
	dma_addr_t dma_addr, unsigned long attrs)
	{
	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
	struct page *page = virt_to_page(vaddr);

	if (!dma_release_from_contiguous(dev, page, count))
	free_pages((unsigned long)vaddr, get_order(size));
	}

	bool arch_dma_alloc_attrs(struct device *dev, gfp_t gfp)
	{
	if (!*dev)
	*dev = &x86_dma_fallback_dev;

	*gfp &= ~(__GFP_DMA \| __GFP_HIGHMEM \| __GFP_DMA32);
	gfp = dma_alloc_coherent_gfp_flags(dev, *gfp);

	if (!is_device_dma_capable(*dev))
	return false;
	return true;

	}
	EXPORT_SYMBOL(arch_dma_alloc_attrs);

	/*
	* See <Documentation/x86/x86_64/boot-options.txt> for the iommu kernel
	* parameter documentation.
	*/
	static __init int iommu_setup(char *p)
	{
	iommu_merge = 1;

	if (!p)
	return -EINVAL;

	while (*p) {
	if (!strncmp(p, "off", 3))
	no_iommu = 1;
	/* gart_parse_options has more force support */
	if (!strncmp(p, "force", 5))
	force_iommu = 1;
	if (!strncmp(p, "noforce", 7)) {
	iommu_merge = 0;
	force_iommu = 0;
	}

	if (!strncmp(p, "biomerge", 8)) {
	iommu_merge = 1;
	force_iommu = 1;
	}
	if (!strncmp(p, "panic", 5))
	panic_on_overflow = 1;
	if (!strncmp(p, "nopanic", 7))
	panic_on_overflow = 0;
	if (!strncmp(p, "merge", 5)) {
	iommu_merge = 1;
	force_iommu = 1;
	}
	if (!strncmp(p, "nomerge", 7))
	iommu_merge = 0;
	if (!strncmp(p, "forcesac", 8))
	iommu_sac_force = 1;
	if (!strncmp(p, "allowdac", 8))
	forbid_dac = 0;
	if (!strncmp(p, "nodac", 5))
	forbid_dac = 1;
	if (!strncmp(p, "usedac", 6)) {
	forbid_dac = -1;
	return 1;
	}
	#ifdef CONFIG_SWIOTLB
	if (!strncmp(p, "soft", 4))
	swiotlb = 1;
	#endif
	if (!strncmp(p, "pt", 2))
	iommu_pass_through = 1;

	gart_parse_options(p);

	#ifdef CONFIG_CALGARY_IOMMU
	if (!strncmp(p, "calgary", 7))
	use_calgary = 1;
	#endif /* CONFIG_CALGARY_IOMMU */

	p += strcspn(p, ",");
	if (*p == ',')
	++p;
	}
	return 0;
	}
	early_param("iommu", iommu_setup);

	int dma_supported(struct device *dev, u64 mask)
	{
	struct dma_map_ops *ops = get_dma_ops(dev);

	#ifdef CONFIG_PCI
	if (mask > 0xffffffff && forbid_dac > 0) {
	dev_info(dev, "PCI: Disallowing DAC for device\n");
	return 0;
	}
	#endif

	if (ops->dma_supported)
	return ops->dma_supported(dev, mask);

	/* Copied from i386. Doesn't make much sense, because it will
	only work for pci_alloc_coherent.
	The caller just has to use GFP_DMA in this case. */
	if (mask < DMA_BIT_MASK(24))
	return 0;

	/* Tell the device to use SAC when IOMMU force is on. This
	allows the driver to use cheaper accesses in some cases.

	Problem with this is that if we overflow the IOMMU area and
	return DAC as fallback address the device may not handle it
	correctly.

	As a special case some controllers have a 39bit address
	mode that is as efficient as 32bit (aic79xx). Don't force
	SAC for these. Assume all masks <= 40 bits are of this
	type. Normally this doesn't make any difference, but gives
	more gentle handling of IOMMU overflow. */
	if (iommu_sac_force && (mask >= DMA_BIT_MASK(40))) {
	dev_info(dev, "Force SAC with mask %Lx\n", mask);
	return 0;
	}

	return 1;
	}
	EXPORT_SYMBOL(dma_supported);

	static int __init pci_iommu_init(void)
	{
	struct iommu_table_entry *p;
	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);

	#ifdef CONFIG_PCI
	dma_debug_add_bus(&pci_bus_type);
	#endif
	x86_init.iommu.iommu_init();

	for (p = __iommu_table; p < __iommu_table_end; p++) {
	if (p && (p->flags & IOMMU_DETECTED) && p->late_init)
	p->late_init();
	}

	return 0;
	}
	/* Must execute after PCI subsystem */
	rootfs_initcall(pci_iommu_init);

	#ifdef CONFIG_PCI
	/* Many VIA bridges seem to corrupt data for DAC. Disable it here */

	static void via_no_dac(struct pci_dev *dev)
	{
	if (forbid_dac == 0) {
	dev_info(&dev->dev, "disabling DAC on VIA PCI bridge\n");
	forbid_dac = 1;
	}
	}
	DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID,
	PCI_CLASS_BRIDGE_PCI, 8, via_no_dac);
	#endif