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Commit 24100055 authored by Joerg Roedel's avatar Joerg Roedel
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x86/amd-iommu: Add device bind reference counting 



This patch adds a reference count to each device to count
how often the device was bound to that domain. This is
important for single devices that act as an alias for a
number of others. These devices must stay bound to their
domains until all devices that alias to it are unbound from
the same domain.

Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent 657cbb6b

arch/x86/include/asm/amd_iommu_types.h

+1 −0
Original line number Diff line number Diff line
@@ -253,6 +253,7 @@ struct protection_domain { 
struct iommu_dev_data {

	struct device *alias;		  /* The Alias Device */

	struct protection_domain *domain; /* Domain the device is bound to */

	atomic_t bind;			  /* Domain attach reverent count */

};



/*

arch/x86/kernel/amd_iommu.c

+29 −8
Original line number Diff line number Diff line
@@ -152,6 +152,8 @@ static int iommu_init_device(struct device *dev) 
	if (pdev)

		dev_data->alias = &pdev->dev;



	atomic_set(&dev_data->bind, 0);



	dev->archdata.iommu = dev_data;
@@ -1403,17 +1405,22 @@ static int __attach_device(struct device *dev, 
		return -EBUSY;



	/* Do real assignment */

	if (alias != devid &&

	    alias_data->domain == NULL) {

	if (alias != devid) {

		if (alias_data->domain == NULL) {

			alias_data->domain = domain;

			set_dte_entry(alias, domain);

		}



		atomic_inc(&alias_data->bind);

	}



	if (dev_data->domain == NULL) {

		dev_data->domain = domain;

		set_dte_entry(devid, domain);

	}



	atomic_inc(&dev_data->bind);



	/* ready */

	spin_unlock(&domain->lock);
@@ -1449,20 +1456,34 @@ static int attach_device(struct device *dev, 
 */

static void __detach_device(struct device *dev)

{

	u16 devid = get_device_id(dev);

	u16 devid = get_device_id(dev), alias;

	struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];

	struct iommu_dev_data *dev_data = get_dev_data(dev);

	struct iommu_dev_data *alias_data;



	BUG_ON(!iommu);



	devid = get_device_id(dev);

	alias = get_device_id(dev_data->alias);



	if (devid != alias) {

		alias_data = get_dev_data(dev_data->alias);

		if (atomic_dec_and_test(&alias_data->bind)) {

			clear_dte_entry(alias);

			alias_data->domain = NULL;

		}

	}



	if (atomic_dec_and_test(&dev_data->bind)) {

		clear_dte_entry(devid);

		dev_data->domain = NULL;

	}



	/*

	 * If we run in passthrough mode the device must be assigned to the

	 * passthrough domain if it is detached from any other domain

	 */

	if (iommu_pass_through)

	if (iommu_pass_through && dev_data->domain == NULL)

		__attach_device(dev, pt_domain);

}