Commit 98b2fffb authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Handle 32bit device with identity default domain 



The iommu driver doesn't know whether the bit width of a PCI
device is sufficient for access to the whole system memory.
Hence, the driver checks this when the driver calls into the
dma APIs. If a device is using an identity domain, but the
bit width is less than the system requirement, we need to use
a dma domain instead. This also applies after we delegated
the domain life cycle management to the upper layer.

Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 942067f1

drivers/iommu/intel-iommu.c

+22 −33
Original line number Diff line number Diff line
@@ -2984,25 +2984,6 @@ static int device_def_domain_type(struct device *dev, int startup) 
			return IOMMU_DOMAIN_DMA;

	}



	/*

	 * At boot time, we don't yet know if devices will be 64-bit capable.

	 * Assume that they will — if they turn out not to be, then we can

	 * take them out of the 1:1 domain later.

	 */

	if (!startup) {

		/*

		 * If the device's dma_mask is less than the system's memory

		 * size then this is not a candidate for identity mapping.

		 */

		u64 dma_mask = *dev->dma_mask;



		if (dev->coherent_dma_mask &&

		    dev->coherent_dma_mask < dma_mask)

			dma_mask = dev->coherent_dma_mask;



		return dma_mask >= dma_get_required_mask(dev);

	}



	return (iommu_identity_mapping & IDENTMAP_ALL) ?

			IOMMU_DOMAIN_IDENTITY : 0;

}
@@ -3614,14 +3595,19 @@ out: 
/* Check if the dev needs to go through non-identity map and unmap process.*/

static bool iommu_need_mapping(struct device *dev)

{

	int found;

	int ret;



	if (iommu_dummy(dev))

		return false;



	found = identity_mapping(dev);

	if (found) {

		if (iommu_should_identity_map(dev, 0))

	ret = identity_mapping(dev);

	if (ret) {

		u64 dma_mask = *dev->dma_mask;



		if (dev->coherent_dma_mask && dev->coherent_dma_mask < dma_mask)

			dma_mask = dev->coherent_dma_mask;



		if (dma_mask >= dma_get_required_mask(dev))

			return false;



		/*
@@ -3629,17 +3615,20 @@ static bool iommu_need_mapping(struct device *dev) 
		 * non-identity mapping.

		 */

		dmar_remove_one_dev_info(dev);

		dev_info(dev, "32bit DMA uses non-identity mapping\n");

	} else {

		/*

		 * In case of a detached 64 bit DMA device from vm, the device

		 * is put into si_domain for identity mapping.

		 */

		if (iommu_should_identity_map(dev, 0) &&

		    !domain_add_dev_info(si_domain, dev)) {

			dev_info(dev, "64bit DMA uses identity mapping\n");

			return false;

		ret = iommu_request_dma_domain_for_dev(dev);

		if (ret) {

			struct iommu_domain *domain;

			struct dmar_domain *dmar_domain;



			domain = iommu_get_domain_for_dev(dev);

			if (domain) {

				dmar_domain = to_dmar_domain(domain);

				dmar_domain->flags |= DOMAIN_FLAG_LOSE_CHILDREN;

			}

			get_valid_domain_for_dev(dev);

		}



		dev_info(dev, "32bit DMA uses non-identity mapping\n");

	}



	return true;

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