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Subject[PATCH 28/34] x86/amd-iommu: Add device bind reference counting
Date
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: Joerg Roedel <joerg.roedel@amd.com>
---
arch/x86/include/asm/amd_iommu_types.h | 1 +
arch/x86/kernel/amd_iommu.c | 37 +++++++++++++++++++++++++-------
2 files changed, 30 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index 9eaa27b..434e90e 100644
--- a/arch/x86/include/asm/amd_iommu_types.h
+++ b/arch/x86/include/asm/amd_iommu_types.h
@@ -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 */
};

/*
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 3214e88..f5db7d5 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -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;


@@ -1403,10 +1405,13 @@ static int __attach_device(struct device *dev,
return -EBUSY;

/* Do real assignment */
- if (alias != devid &&
- alias_data->domain == NULL) {
- alias_data->domain = domain;
- set_dte_entry(alias, domain);
+ 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) {
@@ -1414,6 +1419,8 @@ static int __attach_device(struct device *dev,
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);

- clear_dte_entry(devid);
- dev_data->domain = NULL;
+ 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);
}

--
1.6.5.3



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