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: Joerg Roedel <joerg.roedel@amd.com>

diff --git a/arch/x86/include/asm/amd_iommu_types.h b/arch/x86/include/asm/amd_iommu_types.h
index 9eaa27b46860eac9e03760208100a8e40da45fdb..434e90ed89c5087253e214105ce67ac9a8fb24fe 100644 (file)
--- 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 3214e8806f950a3e7358948bac731ae26d627b08..f5db7d5e444ed4797074373a4fb24a9494a87502 100644 (file)
--- 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);
 }