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iommu/amd: Implement IO page-fault handler
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Register the notifier for PPR faults and handle them as
necessary.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
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Joerg Roedel committed Dec 12, 2011
1 parent 2d5503b commit 028eeac
Showing 1 changed file with 196 additions and 8 deletions.
204 changes: 196 additions & 8 deletions drivers/iommu/amd_iommu_v2.c
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Original file line number Diff line number Diff line change
@@ -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 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
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));
}

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