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iommu/amd: Implement notifiers for IOMMUv2
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Since pages are not pinned anymore we need notifications
when the VMM changes the page-tables. Use mmu_notifiers for
that.
Also use the task_exit notifier from the profiling subsystem
to shutdown all contexts related to this task.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
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Joerg Roedel committed Dec 14, 2011
1 parent 028eeac commit 8736b2c
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Showing 2 changed files with 178 additions and 11 deletions.
3 changes: 2 additions & 1 deletion drivers/iommu/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,8 @@ config AMD_IOMMU_STATS

config AMD_IOMMU_V2
tristate "AMD IOMMU Version 2 driver (EXPERIMENTAL)"
depends on AMD_IOMMU && EXPERIMENTAL
depends on AMD_IOMMU && PROFILING && EXPERIMENTAL
select MMU_NOTIFIER
---help---
This option enables support for the AMD IOMMUv2 features of the IOMMU
hardware. Select this option if you want to use devices that support
Expand Down
186 changes: 176 additions & 10 deletions drivers/iommu/amd_iommu_v2.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,10 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include <linux/mmu_notifier.h>
#include <linux/amd-iommu.h>
#include <linux/mm_types.h>
#include <linux/profile.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/iommu.h>
Expand Down Expand Up @@ -45,6 +47,7 @@ struct pasid_state {
atomic_t count; /* Reference count */
struct task_struct *task; /* Task bound to this PASID */
struct mm_struct *mm; /* mm_struct for the faults */
struct mmu_notifier mn; /* mmu_otifier handle */
struct pri_queue pri[PRI_QUEUE_SIZE]; /* PRI tag states */
struct device_state *device_state; /* Link to our device_state */
int pasid; /* PASID index */
Expand Down Expand Up @@ -85,8 +88,16 @@ static DEFINE_SPINLOCK(ps_lock);

static struct workqueue_struct *iommu_wq;

/*
* Empty page table - Used between
* mmu_notifier_invalidate_range_start and
* mmu_notifier_invalidate_range_end
*/
static u64 *empty_page_table;

static void free_pasid_states(struct device_state *dev_state);
static void unbind_pasid(struct device_state *dev_state, int pasid);
static int task_exit(struct notifier_block *nb, unsigned long e, void *data);

static u16 device_id(struct pci_dev *pdev)
{
Expand Down Expand Up @@ -144,6 +155,11 @@ static void put_device_state_wait(struct device_state *dev_state)

free_device_state(dev_state);
}

static struct notifier_block profile_nb = {
.notifier_call = task_exit,
};

static void link_pasid_state(struct pasid_state *pasid_state)
{
spin_lock(&ps_lock);
Expand Down Expand Up @@ -294,6 +310,23 @@ static void put_pasid_state_wait(struct pasid_state *pasid_state)
free_pasid_state(pasid_state);
}

static void __unbind_pasid(struct pasid_state *pasid_state)
{
struct iommu_domain *domain;

domain = pasid_state->device_state->domain;

amd_iommu_domain_clear_gcr3(domain, pasid_state->pasid);
clear_pasid_state(pasid_state->device_state, pasid_state->pasid);

/* Make sure no more pending faults are in the queue */
flush_workqueue(iommu_wq);

mmu_notifier_unregister(&pasid_state->mn, pasid_state->mm);

put_pasid_state(pasid_state); /* Reference taken in bind() function */
}

static void unbind_pasid(struct device_state *dev_state, int pasid)
{
struct pasid_state *pasid_state;
Expand All @@ -303,12 +336,8 @@ static void unbind_pasid(struct device_state *dev_state, int pasid)
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_wait(pasid_state); /* Reference from bind() function */
__unbind_pasid(pasid_state);
put_pasid_state_wait(pasid_state); /* Reference taken in this function */
}

static void free_pasid_states_level1(struct pasid_state **tbl)
Expand Down Expand Up @@ -361,6 +390,83 @@ static void free_pasid_states(struct device_state *dev_state)
free_page((unsigned long)dev_state->states);
}

static struct pasid_state *mn_to_state(struct mmu_notifier *mn)
{
return container_of(mn, struct pasid_state, mn);
}

static void __mn_flush_page(struct mmu_notifier *mn,
unsigned long address)
{
struct pasid_state *pasid_state;
struct device_state *dev_state;

pasid_state = mn_to_state(mn);
dev_state = pasid_state->device_state;

amd_iommu_flush_page(dev_state->domain, pasid_state->pasid, address);
}

static int mn_clear_flush_young(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long address)
{
__mn_flush_page(mn, address);

return 0;
}

static void mn_change_pte(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long address,
pte_t pte)
{
__mn_flush_page(mn, address);
}

static void mn_invalidate_page(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long address)
{
__mn_flush_page(mn, address);
}

static void mn_invalidate_range_start(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start, unsigned long end)
{
struct pasid_state *pasid_state;
struct device_state *dev_state;

pasid_state = mn_to_state(mn);
dev_state = pasid_state->device_state;

amd_iommu_domain_set_gcr3(dev_state->domain, pasid_state->pasid,
__pa(empty_page_table));
}

static void mn_invalidate_range_end(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start, unsigned long end)
{
struct pasid_state *pasid_state;
struct device_state *dev_state;

pasid_state = mn_to_state(mn);
dev_state = pasid_state->device_state;

amd_iommu_domain_set_gcr3(dev_state->domain, pasid_state->pasid,
__pa(pasid_state->mm->pgd));
}

static struct mmu_notifier_ops iommu_mn = {
.clear_flush_young = mn_clear_flush_young,
.change_pte = mn_change_pte,
.invalidate_page = mn_invalidate_page,
.invalidate_range_start = mn_invalidate_range_start,
.invalidate_range_end = mn_invalidate_range_end,
};

static void set_pri_tag_status(struct pasid_state *pasid_state,
u16 tag, int status)
{
Expand Down Expand Up @@ -475,6 +581,50 @@ static struct notifier_block ppr_nb = {
.notifier_call = ppr_notifier,
};

static int task_exit(struct notifier_block *nb, unsigned long e, void *data)
{
struct pasid_state *pasid_state;
struct task_struct *task;

task = data;

/*
* Using this notifier is a hack - but there is no other choice
* at the moment. What I really want is a sleeping notifier that
* is called when an MM goes down. But such a notifier doesn't
* exist yet. The notifier needs to sleep because it has to make
* sure that the device does not use the PASID and the address
* space anymore before it is destroyed. This includes waiting
* for pending PRI requests to pass the workqueue. The
* MMU-Notifiers would be a good fit, but they use RCU and so
* they are not allowed to sleep. Lets see how we can solve this
* in a more intelligent way in the future.
*/
again:
spin_lock(&ps_lock);
list_for_each_entry(pasid_state, &pasid_state_list, list) {
struct device_state *dev_state;
int pasid;

if (pasid_state->task != task)
continue;

/* Drop Lock and unbind */
spin_unlock(&ps_lock);

dev_state = pasid_state->device_state;
pasid = pasid_state->pasid;

unbind_pasid(dev_state, pasid);

/* Task may be in the list multiple times */
goto again;
}
spin_unlock(&ps_lock);

return NOTIFY_OK;
}

int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
struct task_struct *task)
{
Expand Down Expand Up @@ -509,13 +659,16 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
pasid_state->mm = get_task_mm(task);
pasid_state->device_state = dev_state;
pasid_state->pasid = pasid;
pasid_state->mn.ops = &iommu_mn;

if (pasid_state->mm == NULL)
goto out_free;

mmu_notifier_register(&pasid_state->mn, pasid_state->mm);

ret = set_pasid_state(dev_state, pasid_state, pasid);
if (ret)
goto out_free;
goto out_unregister;

ret = amd_iommu_domain_set_gcr3(dev_state->domain, pasid,
__pa(pasid_state->mm->pgd));
Expand All @@ -529,6 +682,9 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
out_clear_state:
clear_pasid_state(dev_state, pasid);

out_unregister:
mmu_notifier_unregister(&pasid_state->mn, pasid_state->mm);

out_free:
free_pasid_state(pasid_state);

Expand Down Expand Up @@ -689,15 +845,22 @@ static int __init amd_iommu_v2_init(void)

ret = -ENOMEM;
iommu_wq = create_workqueue("amd_iommu_v2");
if (iommu_wq == NULL) {
ret = -ENOMEM;
if (iommu_wq == NULL)
goto out_free;
}

ret = -ENOMEM;
empty_page_table = (u64 *)get_zeroed_page(GFP_KERNEL);
if (empty_page_table == NULL)
goto out_destroy_wq;

amd_iommu_register_ppr_notifier(&ppr_nb);
profile_event_register(PROFILE_TASK_EXIT, &profile_nb);

return 0;

out_destroy_wq:
destroy_workqueue(iommu_wq);

out_free:
free_pages((unsigned long)state_table, get_order(state_table_size));

Expand All @@ -710,6 +873,7 @@ static void __exit amd_iommu_v2_exit(void)
size_t state_table_size;
int i;

profile_event_unregister(PROFILE_TASK_EXIT, &profile_nb);
amd_iommu_unregister_ppr_notifier(&ppr_nb);

flush_workqueue(iommu_wq);
Expand All @@ -734,6 +898,8 @@ static void __exit amd_iommu_v2_exit(void)

state_table_size = MAX_DEVICES * sizeof(struct device_state *);
free_pages((unsigned long)state_table, get_order(state_table_size));

free_page((unsigned long)empty_page_table);
}

module_init(amd_iommu_v2_init);
Expand Down

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