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Commit 19943b0e authored by David Woodhouse's avatar David Woodhouse
Browse files

intel-iommu: Unify hardware and software passthrough support 



This makes the hardware passthrough mode work a lot more like the
software version, so that the behaviour of a kernel with 'iommu=pt'
is the same whether the hardware supports passthrough or not.

In particular:
 - We use a single si_domain for the pass-through devices.
 - 32-bit devices can be taken out of the pass-through domain so that
   they don't have to use swiotlb.
 - Devices will work again after being removed from a KVM guest.
 - A potential oops on OOM (in init_context_pass_through()) is fixed.

Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 0815565a

arch/x86/kernel/pci-swiotlb.c

+2 −3
Original line number Diff line number Diff line
@@ -71,8 +71,7 @@ void __init pci_swiotlb_init(void) 
{

	/* don't initialize swiotlb if iommu=off (no_iommu=1) */

#ifdef CONFIG_X86_64

	if ((!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN) ||

		iommu_pass_through)

	if ((!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN))

		swiotlb = 1;

#endif

	if (swiotlb_force)

drivers/pci/intel-iommu.c

+74 −100
Original line number Diff line number Diff line
@@ -251,7 +251,8 @@ static inline int first_pte_in_page(struct dma_pte *pte) 
 * 	2. It maps to each iommu if successful.

 *	3. Each iommu mapps to this domain if successful.

 */

struct dmar_domain *si_domain;

static struct dmar_domain *si_domain;

static int hw_pass_through = 1;



/* devices under the same p2p bridge are owned in one domain */

#define DOMAIN_FLAG_P2P_MULTIPLE_DEVICES (1 << 0)
@@ -1948,14 +1949,24 @@ static int iommu_prepare_identity_map(struct pci_dev *pdev, 
	struct dmar_domain *domain;

	int ret;



	printk(KERN_INFO

	       "IOMMU: Setting identity map for device %s [0x%Lx - 0x%Lx]\n",

	       pci_name(pdev), start, end);



	domain = get_domain_for_dev(pdev, DEFAULT_DOMAIN_ADDRESS_WIDTH);

	if (!domain)

		return -ENOMEM;



	/* For _hardware_ passthrough, don't bother. But for software

	   passthrough, we do it anyway -- it may indicate a memory

	   range which is reserved in E820, so which didn't get set

	   up to start with in si_domain */

	if (domain == si_domain && hw_pass_through) {

		printk("Ignoring identity map for HW passthrough device %s [0x%Lx - 0x%Lx]\n",

		       pci_name(pdev), start, end);

		return 0;

	}



	printk(KERN_INFO

	       "IOMMU: Setting identity map for device %s [0x%Lx - 0x%Lx]\n",

	       pci_name(pdev), start, end);



	ret = iommu_domain_identity_map(domain, start, end);

	if (ret)

		goto error;
@@ -2006,23 +2017,6 @@ static inline void iommu_prepare_isa(void) 
}

#endif /* !CONFIG_DMAR_FLPY_WA */



/* Initialize each context entry as pass through.*/

static int __init init_context_pass_through(void)

{

	struct pci_dev *pdev = NULL;

	struct dmar_domain *domain;

	int ret;



	for_each_pci_dev(pdev) {

		domain = get_domain_for_dev(pdev, DEFAULT_DOMAIN_ADDRESS_WIDTH);

		ret = domain_context_mapping(domain, pdev,

					     CONTEXT_TT_PASS_THROUGH);

		if (ret)

			return ret;

	}

	return 0;

}



static int md_domain_init(struct dmar_domain *domain, int guest_width);



static int __init si_domain_work_fn(unsigned long start_pfn,
@@ -2037,7 +2031,7 @@ static int __init si_domain_work_fn(unsigned long start_pfn, 


}



static int si_domain_init(void)

static int si_domain_init(int hw)

{

	struct dmar_drhd_unit *drhd;

	struct intel_iommu *iommu;
@@ -2064,6 +2058,9 @@ static int si_domain_init(void) 


	si_domain->flags = DOMAIN_FLAG_STATIC_IDENTITY;



	if (hw)

		return 0;



	for_each_online_node(nid) {

		work_with_active_regions(nid, si_domain_work_fn, &ret);

		if (ret)
@@ -2155,24 +2152,26 @@ static int iommu_should_identity_map(struct pci_dev *pdev, int startup) 
	return 1;

}



static int iommu_prepare_static_identity_mapping(void)

static int iommu_prepare_static_identity_mapping(int hw)

{

	struct pci_dev *pdev = NULL;

	int ret;



	ret = si_domain_init();

	ret = si_domain_init(hw);

	if (ret)

		return -EFAULT;



	for_each_pci_dev(pdev) {

		if (iommu_should_identity_map(pdev, 1)) {

			printk(KERN_INFO "IOMMU: identity mapping for device %s\n",

			       pci_name(pdev));

			printk(KERN_INFO "IOMMU: %s identity mapping for device %s\n",

			       hw ? "hardware" : "software", pci_name(pdev));



			ret = domain_context_mapping(si_domain, pdev,

						     hw ? CONTEXT_TT_PASS_THROUGH :

						     CONTEXT_TT_MULTI_LEVEL);

			if (ret)

				return ret;



			ret = domain_add_dev_info(si_domain, pdev);

			if (ret)

				return ret;
@@ -2189,14 +2188,6 @@ int __init init_dmars(void) 
	struct pci_dev *pdev;

	struct intel_iommu *iommu;

	int i, ret;

	int pass_through = 1;



	/*

	 * In case pass through can not be enabled, iommu tries to use identity

	 * mapping.

	 */

	if (iommu_pass_through)

		iommu_identity_mapping = 1;



	/*

	 * for each drhd
@@ -2250,13 +2241,7 @@ int __init init_dmars(void) 
			goto error;

		}

		if (!ecap_pass_through(iommu->ecap))

			pass_through = 0;

	}

	if (iommu_pass_through)

		if (!pass_through) {

			printk(KERN_INFO

			       "Pass Through is not supported by hardware.\n");

			iommu_pass_through = 0;

			hw_pass_through = 0;

	}



	/*
@@ -2312,30 +2297,24 @@ int __init init_dmars(void) 
		}

	}



	/*

	 * If pass through is set and enabled, context entries of all pci

	 * devices are intialized by pass through translation type.

	 */

	if (iommu_pass_through) {

		ret = init_context_pass_through();

		if (ret) {

			printk(KERN_ERR "IOMMU: Pass through init failed.\n");

			iommu_pass_through = 0;

		}

	}



	if (iommu_pass_through)

		iommu_identity_mapping = 1;

#ifdef CONFIG_DMAR_BROKEN_GFX_WA

	else

		iommu_identity_mapping = 2;

#endif

	/*

	 * If pass through is not set or not enabled, setup context entries for

	 * identity mappings for rmrr, gfx, and isa and may fall back to static

	 * identity mapping if iommu_identity_mapping is set.

	 */

	if (!iommu_pass_through) {

#ifdef CONFIG_DMAR_BROKEN_GFX_WA

		if (!iommu_identity_mapping)

			iommu_identity_mapping = 2;

#endif

		if (iommu_identity_mapping)

			iommu_prepare_static_identity_mapping();

	if (iommu_identity_mapping) {

		ret = iommu_prepare_static_identity_mapping(hw_pass_through);

		if (ret) {

			printk(KERN_CRIT "Failed to setup IOMMU pass-through\n");

			goto error;

		}

	}

	/*

	 * For each rmrr

	 *   for each dev attached to rmrr
@@ -2368,7 +2347,6 @@ int __init init_dmars(void) 
	}



	iommu_prepare_isa();

	}



	/*

	 * for each drhd
@@ -2536,7 +2514,10 @@ static int iommu_no_mapping(struct device *dev) 
			ret = domain_add_dev_info(si_domain, pdev);

			if (ret)

				return 0;

			ret = domain_context_mapping(si_domain, pdev, CONTEXT_TT_MULTI_LEVEL);

			ret = domain_context_mapping(si_domain, pdev,

						     hw_pass_through ?

						     CONTEXT_TT_PASS_THROUGH :

						     CONTEXT_TT_MULTI_LEVEL);

			if (!ret) {

				printk(KERN_INFO "64bit %s uses identity mapping\n",

				       pci_name(pdev));
@@ -3202,7 +3183,7 @@ int __init intel_iommu_init(void) 
	 * Check the need for DMA-remapping initialization now.

	 * Above initialization will also be used by Interrupt-remapping.

	 */

	if (no_iommu || (swiotlb && !iommu_pass_through) || dmar_disabled)

	if (no_iommu || swiotlb || dmar_disabled)

		return -ENODEV;



	iommu_init_mempool();
@@ -3222,14 +3203,7 @@ int __init intel_iommu_init(void) 


	init_timer(&unmap_timer);

	force_iommu = 1;



	if (!iommu_pass_through) {

		printk(KERN_INFO

		       "Multi-level page-table translation for DMAR.\n");

	dma_ops = &intel_dma_ops;

	} else

		printk(KERN_INFO

		       "DMAR: Pass through translation for DMAR.\n");



	init_iommu_sysfs();