iommu/amd: Implement IO page-fault handler

Register the notifier for PPR faults and handle them as
necessary.

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

1 files changed, 196 insertions, 8 deletions

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index b5ee09ece651..8804b2247694 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -21,9 +21,11 @@
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/iommu.h>
+#include <linux/wait.h>
 #include <linux/pci.h>
 #include <linux/gfp.h>
 
+#include "amd_iommu_types.h"
 #include "amd_iommu_proto.h"
 
 MODULE_LICENSE("GPL v2");
@@ -35,6 +37,7 @@ MODULE_AUTHOR("Joerg Roedel <joerg.roedel@amd.com>");
 struct pri_queue {
         atomic_t inflight;
         bool finish;
+        int status;
 };
 
 struct pasid_state {
@@ -45,6 +48,8 @@ struct pasid_state {
         struct pri_queue pri[PRI_QUEUE_SIZE];   /* PRI tag states */
         struct device_state *device_state;      /* Link to our device_state */
         int pasid;                              /* PASID index */
+        spinlock_t lock;                        /* Protect pri_queues */
+        wait_queue_head_t wq;                   /* To wait for count == 0 */
 };
 
 struct device_state {
@@ -55,6 +60,20 @@ struct device_state {
         int pasid_levels;
         int max_pasids;
         spinlock_t lock;
+        wait_queue_head_t wq;
+};
+
+struct fault {
+        struct work_struct work;
+        struct device_state *dev_state;
+        struct pasid_state *state;
+        struct mm_struct *mm;
+        u64 address;
+        u16 devid;
+        u16 pasid;
+        u16 tag;
+        u16 finish;
+        u16 flags;
 };
 
 struct device_state **state_table;
@@ -64,6 +83,8 @@ static spinlock_t state_lock;
 static LIST_HEAD(pasid_state_list);
 static DEFINE_SPINLOCK(ps_lock);
 
+static struct workqueue_struct *iommu_wq;
+
 static void free_pasid_states(struct device_state *dev_state);
 static void unbind_pasid(struct device_state *dev_state, int pasid);
 
@@ -109,9 +130,20 @@ static void free_device_state(struct device_state *dev_state)
 static void put_device_state(struct device_state *dev_state)
 {
         if (atomic_dec_and_test(&dev_state->count))
-                free_device_state(dev_state);
+                wake_up(&dev_state->wq);
 }
 
+static void put_device_state_wait(struct device_state *dev_state)
+{
+        DEFINE_WAIT(wait);
+
+        prepare_to_wait(&dev_state->wq, &wait, TASK_UNINTERRUPTIBLE);
+        if (!atomic_dec_and_test(&dev_state->count))
+                schedule();
+        finish_wait(&dev_state->wq, &wait);
+
+        free_device_state(dev_state);
+}
 static void link_pasid_state(struct pasid_state *pasid_state)
 {
         spin_lock(&ps_lock);
@@ -242,11 +274,26 @@ 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);
+                wake_up(&pasid_state->wq);
         }
 }
 
+static void put_pasid_state_wait(struct pasid_state *pasid_state)
+{
+        DEFINE_WAIT(wait);
+
+        prepare_to_wait(&pasid_state->wq, &wait, TASK_UNINTERRUPTIBLE);
+
+        if (atomic_dec_and_test(&pasid_state->count))
+                put_device_state(pasid_state->device_state);
+        else
+                schedule();
+
+        finish_wait(&pasid_state->wq, &wait);
+        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;
@@ -261,7 +308,7 @@ static void unbind_pasid(struct device_state *dev_state, int 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 */
+        put_pasid_state_wait(pasid_state); /* Reference from bind() function */
 }
 
 static void free_pasid_states_level1(struct pasid_state **tbl)
@@ -300,8 +347,8 @@ static void free_pasid_states(struct device_state *dev_state)
                 if (pasid_state == NULL)
                         continue;
 
-                unbind_pasid(dev_state, i);
                 put_pasid_state(pasid_state);
+                unbind_pasid(dev_state, i);
         }
 
         if (dev_state->pasid_levels == 2)
@@ -314,6 +361,120 @@ static void free_pasid_states(struct device_state *dev_state)
         free_page((unsigned long)dev_state->states);
 }
 
+static void set_pri_tag_status(struct pasid_state *pasid_state,
+                               u16 tag, int status)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&pasid_state->lock, flags);
+        pasid_state->pri[tag].status = status;
+        spin_unlock_irqrestore(&pasid_state->lock, flags);
+}
+
+static void finish_pri_tag(struct device_state *dev_state,
+                           struct pasid_state *pasid_state,
+                           u16 tag)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&pasid_state->lock, flags);
+        if (atomic_dec_and_test(&pasid_state->pri[tag].inflight) &&
+            pasid_state->pri[tag].finish) {
+                amd_iommu_complete_ppr(dev_state->pdev, pasid_state->pasid,
+                                       pasid_state->pri[tag].status, tag);
+                pasid_state->pri[tag].finish = false;
+                pasid_state->pri[tag].status = PPR_SUCCESS;
+        }
+        spin_unlock_irqrestore(&pasid_state->lock, flags);
+}
+
+static void do_fault(struct work_struct *work)
+{
+        struct fault *fault = container_of(work, struct fault, work);
+        int npages, write;
+        struct page *page;
+
+        write = !!(fault->flags & PPR_FAULT_WRITE);
+
+        npages = get_user_pages(fault->state->task, fault->state->mm,
+                                fault->address, 1, write, 0, &page, NULL);
+
+        if (npages == 1)
+                put_page(page);
+        else
+                set_pri_tag_status(fault->state, fault->tag, PPR_INVALID);
+
+        finish_pri_tag(fault->dev_state, fault->state, fault->tag);
+
+        put_pasid_state(fault->state);
+
+        kfree(fault);
+}
+
+static int ppr_notifier(struct notifier_block *nb, unsigned long e, void *data)
+{
+        struct amd_iommu_fault *iommu_fault;
+        struct pasid_state *pasid_state;
+        struct device_state *dev_state;
+        unsigned long flags;
+        struct fault *fault;
+        bool finish;
+        u16 tag;
+        int ret;
+
+        iommu_fault = data;
+        tag         = iommu_fault->tag & 0x1ff;
+        finish      = (iommu_fault->tag >> 9) & 1;
+
+        ret = NOTIFY_DONE;
+        dev_state = get_device_state(iommu_fault->device_id);
+        if (dev_state == NULL)
+                goto out;
+
+        pasid_state = get_pasid_state(dev_state, iommu_fault->pasid);
+        if (pasid_state == NULL) {
+                /* We know the device but not the PASID -> send INVALID */
+                amd_iommu_complete_ppr(dev_state->pdev, iommu_fault->pasid,
+                                       PPR_INVALID, tag);
+                goto out_drop_state;
+        }
+
+        spin_lock_irqsave(&pasid_state->lock, flags);
+        atomic_inc(&pasid_state->pri[tag].inflight);
+        if (finish)
+                pasid_state->pri[tag].finish = true;
+        spin_unlock_irqrestore(&pasid_state->lock, flags);
+
+        fault = kzalloc(sizeof(*fault), GFP_ATOMIC);
+        if (fault == NULL) {
+                /* We are OOM - send success and let the device re-fault */
+                finish_pri_tag(dev_state, pasid_state, tag);
+                goto out_drop_state;
+        }
+
+        fault->dev_state = dev_state;
+        fault->address   = iommu_fault->address;
+        fault->state     = pasid_state;
+        fault->tag       = tag;
+        fault->finish    = finish;
+        fault->flags     = iommu_fault->flags;
+        INIT_WORK(&fault->work, do_fault);
+
+        queue_work(iommu_wq, &fault->work);
+
+        ret = NOTIFY_OK;
+
+out_drop_state:
+        put_device_state(dev_state);
+
+out:
+        return ret;
+}
+
+static struct notifier_block ppr_nb = {
+        .notifier_call = ppr_notifier,
+};
+
 int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
                          struct task_struct *task)
 {
@@ -343,6 +504,7 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
                 goto out;
 
         atomic_set(&pasid_state->count, 1);
+        init_waitqueue_head(&pasid_state->wq);
         pasid_state->task         = task;
         pasid_state->mm           = get_task_mm(task);
         pasid_state->device_state = dev_state;
@@ -368,7 +530,7 @@ out_clear_state:
         clear_pasid_state(dev_state, pasid);
 
 out_free:
-        put_pasid_state(pasid_state);
+        free_pasid_state(pasid_state);
 
 out:
         put_device_state(dev_state);
@@ -424,6 +586,7 @@ int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
                 return -ENOMEM;
 
         spin_lock_init(&dev_state->lock);
+        init_waitqueue_head(&dev_state->wq);
         dev_state->pdev = pdev;
 
         tmp = pasids;
@@ -505,13 +668,14 @@ void amd_iommu_free_device(struct pci_dev *pdev)
         /* Get rid of any remaining pasid states */
         free_pasid_states(dev_state);
 
-        put_device_state(dev_state);
+        put_device_state_wait(dev_state);
 }
 EXPORT_SYMBOL(amd_iommu_free_device);
 
 static int __init amd_iommu_v2_init(void)
 {
         size_t state_table_size;
+        int ret;
 
         pr_info("AMD IOMMUv2 driver by Joerg Roedel <joerg.roedel@amd.com>");
 
@@ -523,7 +687,21 @@ static int __init amd_iommu_v2_init(void)
         if (state_table == NULL)
                 return -ENOMEM;
 
+        ret = -ENOMEM;
+        iommu_wq = create_workqueue("amd_iommu_v2");
+        if (iommu_wq == NULL) {
+                ret = -ENOMEM;
+                goto out_free;
+        }
+
+        amd_iommu_register_ppr_notifier(&ppr_nb);
+
         return 0;
+
+out_free:
+        free_pages((unsigned long)state_table, get_order(state_table_size));
+
+        return ret;
 }
 
 static void __exit amd_iommu_v2_exit(void)
@@ -532,6 +710,14 @@ static void __exit amd_iommu_v2_exit(void)
         size_t state_table_size;
         int i;
 
+        amd_iommu_unregister_ppr_notifier(&ppr_nb);
+
+        flush_workqueue(iommu_wq);
+
+        /*
+         * The loop below might call flush_workqueue(), so call
+         * destroy_workqueue() after it
+         */
         for (i = 0; i < MAX_DEVICES; ++i) {
                 dev_state = get_device_state(i);
 
@@ -540,10 +726,12 @@ static void __exit amd_iommu_v2_exit(void)
 
                 WARN_ON_ONCE(1);
 
-                amd_iommu_free_device(dev_state->pdev);
                 put_device_state(dev_state);
+                amd_iommu_free_device(dev_state->pdev);
         }
 
+        destroy_workqueue(iommu_wq);
+
         state_table_size = MAX_DEVICES * sizeof(struct device_state *);
         free_pages((unsigned long)state_table, get_order(state_table_size));
 }