iommu/amd: Add routines to bind/unbind a pasid

This patch adds routines to bind a specific process
address-space to a given PASID.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 306 insertions, 0 deletions

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index bfceed25c186..b5ee09ece651 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -19,6 +19,7 @@
 #include <linux/amd-iommu.h>
 #include <linux/mm_types.h>
 #include <linux/module.h>
+#include <linux/sched.h>
 #include <linux/iommu.h>
 #include <linux/pci.h>
 #include <linux/gfp.h>
@@ -61,6 +62,10 @@ static spinlock_t state_lock;
 
 /* List and lock for all pasid_states */
 static LIST_HEAD(pasid_state_list);
+static DEFINE_SPINLOCK(ps_lock);
+
+static void free_pasid_states(struct device_state *dev_state);
+static void unbind_pasid(struct device_state *dev_state, int pasid);
 
 static u16 device_id(struct pci_dev *pdev)
 {
@@ -88,8 +93,16 @@ static struct device_state *get_device_state(u16 devid)
 
 static void free_device_state(struct device_state *dev_state)
 {
+        /*
+         * First detach device from domain - No more PRI requests will arrive
+         * from that device after it is unbound from the IOMMUv2 domain.
+         */
         iommu_detach_device(dev_state->domain, &dev_state->pdev->dev);
+
+        /* Everything is down now, free the IOMMUv2 domain */
         iommu_domain_free(dev_state->domain);
+
+        /* Finally get rid of the device-state */
         kfree(dev_state);
 }
 
@@ -99,6 +112,296 @@ static void put_device_state(struct device_state *dev_state)
                 free_device_state(dev_state);
 }
 
+static void link_pasid_state(struct pasid_state *pasid_state)
+{
+        spin_lock(&ps_lock);
+        list_add_tail(&pasid_state->list, &pasid_state_list);
+        spin_unlock(&ps_lock);
+}
+
+static void __unlink_pasid_state(struct pasid_state *pasid_state)
+{
+        list_del(&pasid_state->list);
+}
+
+static void unlink_pasid_state(struct pasid_state *pasid_state)
+{
+        spin_lock(&ps_lock);
+        __unlink_pasid_state(pasid_state);
+        spin_unlock(&ps_lock);
+}
+
+/* Must be called under dev_state->lock */
+static struct pasid_state **__get_pasid_state_ptr(struct device_state *dev_state,
+                                                  int pasid, bool alloc)
+{
+        struct pasid_state **root, **ptr;
+        int level, index;
+
+        level = dev_state->pasid_levels;
+        root  = dev_state->states;
+
+        while (true) {
+
+                index = (pasid >> (9 * level)) & 0x1ff;
+                ptr   = &root[index];
+
+                if (level == 0)
+                        break;
+
+                if (*ptr == NULL) {
+                        if (!alloc)
+                                return NULL;
+
+                        *ptr = (void *)get_zeroed_page(GFP_ATOMIC);
+                        if (*ptr == NULL)
+                                return NULL;
+                }
+
+                root   = (struct pasid_state **)*ptr;
+                level -= 1;
+        }
+
+        return ptr;
+}
+
+static int set_pasid_state(struct device_state *dev_state,
+                           struct pasid_state *pasid_state,
+                           int pasid)
+{
+        struct pasid_state **ptr;
+        unsigned long flags;
+        int ret;
+
+        spin_lock_irqsave(&dev_state->lock, flags);
+        ptr = __get_pasid_state_ptr(dev_state, pasid, true);
+
+        ret = -ENOMEM;
+        if (ptr == NULL)
+                goto out_unlock;
+
+        ret = -ENOMEM;
+        if (*ptr != NULL)
+                goto out_unlock;
+
+        *ptr = pasid_state;
+
+        ret = 0;
+
+out_unlock:
+        spin_unlock_irqrestore(&dev_state->lock, flags);
+
+        return ret;
+}
+
+static void clear_pasid_state(struct device_state *dev_state, int pasid)
+{
+        struct pasid_state **ptr;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev_state->lock, flags);
+        ptr = __get_pasid_state_ptr(dev_state, pasid, true);
+
+        if (ptr == NULL)
+                goto out_unlock;
+
+        *ptr = NULL;
+
+out_unlock:
+        spin_unlock_irqrestore(&dev_state->lock, flags);
+}
+
+static struct pasid_state *get_pasid_state(struct device_state *dev_state,
+                                           int pasid)
+{
+        struct pasid_state **ptr, *ret = NULL;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dev_state->lock, flags);
+        ptr = __get_pasid_state_ptr(dev_state, pasid, false);
+
+        if (ptr == NULL)
+                goto out_unlock;
+
+        ret = *ptr;
+        if (ret)
+                atomic_inc(&ret->count);
+
+out_unlock:
+        spin_unlock_irqrestore(&dev_state->lock, flags);
+
+        return ret;
+}
+
+static void free_pasid_state(struct pasid_state *pasid_state)
+{
+        kfree(pasid_state);
+}
+
+static void put_pasid_state(struct pasid_state *pasid_state)
+{
+        if (atomic_dec_and_test(&pasid_state->count)) {
+                put_device_state(pasid_state->device_state);
+                mmput(pasid_state->mm);
+                free_pasid_state(pasid_state);
+        }
+}
+
+static void unbind_pasid(struct device_state *dev_state, int pasid)
+{
+        struct pasid_state *pasid_state;
+
+        pasid_state = get_pasid_state(dev_state, pasid);
+        if (pasid_state == NULL)
+                return;
+
+        unlink_pasid_state(pasid_state);
+
+        amd_iommu_domain_clear_gcr3(dev_state->domain, pasid);
+        clear_pasid_state(dev_state, pasid);
+
+        put_pasid_state(pasid_state); /* Reference taken in this function */
+        put_pasid_state(pasid_state); /* Reference taken in bind() function */
+}
+
+static void free_pasid_states_level1(struct pasid_state **tbl)
+{
+        int i;
+
+        for (i = 0; i < 512; ++i) {
+                if (tbl[i] == NULL)
+                        continue;
+
+                free_page((unsigned long)tbl[i]);
+        }
+}
+
+static void free_pasid_states_level2(struct pasid_state **tbl)
+{
+        struct pasid_state **ptr;
+        int i;
+
+        for (i = 0; i < 512; ++i) {
+                if (tbl[i] == NULL)
+                        continue;
+
+                ptr = (struct pasid_state **)tbl[i];
+                free_pasid_states_level1(ptr);
+        }
+}
+
+static void free_pasid_states(struct device_state *dev_state)
+{
+        struct pasid_state *pasid_state;
+        int i;
+
+        for (i = 0; i < dev_state->max_pasids; ++i) {
+                pasid_state = get_pasid_state(dev_state, i);
+                if (pasid_state == NULL)
+                        continue;
+
+                unbind_pasid(dev_state, i);
+                put_pasid_state(pasid_state);
+        }
+
+        if (dev_state->pasid_levels == 2)
+                free_pasid_states_level2(dev_state->states);
+        else if (dev_state->pasid_levels == 1)
+                free_pasid_states_level1(dev_state->states);
+        else if (dev_state->pasid_levels != 0)
+                BUG();
+
+        free_page((unsigned long)dev_state->states);
+}
+
+int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
+                         struct task_struct *task)
+{
+        struct pasid_state *pasid_state;
+        struct device_state *dev_state;
+        u16 devid;
+        int ret;
+
+        might_sleep();
+
+        if (!amd_iommu_v2_supported())
+                return -ENODEV;
+
+        devid     = device_id(pdev);
+        dev_state = get_device_state(devid);
+
+        if (dev_state == NULL)
+                return -EINVAL;
+
+        ret = -EINVAL;
+        if (pasid < 0 || pasid >= dev_state->max_pasids)
+                goto out;
+
+        ret = -ENOMEM;
+        pasid_state = kzalloc(sizeof(*pasid_state), GFP_KERNEL);
+        if (pasid_state == NULL)
+                goto out;
+
+        atomic_set(&pasid_state->count, 1);
+        pasid_state->task         = task;
+        pasid_state->mm           = get_task_mm(task);
+        pasid_state->device_state = dev_state;
+        pasid_state->pasid        = pasid;
+
+        if (pasid_state->mm == NULL)
+                goto out_free;
+
+        ret = set_pasid_state(dev_state, pasid_state, pasid);
+        if (ret)
+                goto out_free;
+
+        ret = amd_iommu_domain_set_gcr3(dev_state->domain, pasid,
+                                        __pa(pasid_state->mm->pgd));
+        if (ret)
+                goto out_clear_state;
+
+        link_pasid_state(pasid_state);
+
+        return 0;
+
+out_clear_state:
+        clear_pasid_state(dev_state, pasid);
+
+out_free:
+        put_pasid_state(pasid_state);
+
+out:
+        put_device_state(dev_state);
+
+        return ret;
+}
+EXPORT_SYMBOL(amd_iommu_bind_pasid);
+
+void amd_iommu_unbind_pasid(struct pci_dev *pdev, int pasid)
+{
+        struct device_state *dev_state;
+        u16 devid;
+
+        might_sleep();
+
+        if (!amd_iommu_v2_supported())
+                return;
+
+        devid = device_id(pdev);
+        dev_state = get_device_state(devid);
+        if (dev_state == NULL)
+                return;
+
+        if (pasid < 0 || pasid >= dev_state->max_pasids)
+                goto out;
+
+        unbind_pasid(dev_state, pasid);
+
+out:
+        put_device_state(dev_state);
+}
+EXPORT_SYMBOL(amd_iommu_unbind_pasid);
+
 int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
 {
         struct device_state *dev_state;
@@ -199,6 +502,9 @@ void amd_iommu_free_device(struct pci_dev *pdev)
 
         spin_unlock_irqrestore(&state_lock, flags);
 
+        /* Get rid of any remaining pasid states */
+        free_pasid_states(dev_state);
+
         put_device_state(dev_state);
 }
 EXPORT_SYMBOL(amd_iommu_free_device);