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Date: Tue, 20 May 2014 23:18:24 +0200
From: Joerg Roedel <joro@...tes.org>
To: iommu@...ts.linux-foundation.org
Cc: linux-kernel@...r.kernel.org, Jay.Cornwall@....com,
Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 3/5] iommu/amd: Implement mmu_notifier_release call-back
From: Joerg Roedel <jroedel@...e.de>
Since mmu_notifier call-backs can sleep (because they use
SRCU now) we can use them to tear down PASID mappings. This
allows us to finally remove the hack to use the task_exit
notifier from oprofile to get notified when a process dies.
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Tested-by: Jay Cornwall <Jay.Cornwall@....com>
---
drivers/iommu/amd_iommu_v2.c | 91 ++++++++++++++++--------------------------
1 file changed, 35 insertions(+), 56 deletions(-)
diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 05e93f1..c06a29a 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -101,7 +101,6 @@ 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)
{
@@ -172,10 +171,6 @@ 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);
@@ -393,7 +388,12 @@ static void free_pasid_states(struct device_state *dev_state)
continue;
put_pasid_state(pasid_state);
- unbind_pasid(dev_state, i);
+
+ /*
+ * This will call the mn_release function and
+ * unbind the PASID
+ */
+ mmu_notifier_unregister(&pasid_state->mn, pasid_state->mm);
}
if (dev_state->pasid_levels == 2)
@@ -475,7 +475,24 @@ static void mn_invalidate_range_end(struct mmu_notifier *mn,
__pa(pasid_state->mm->pgd));
}
+static void mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ struct pasid_state *pasid_state;
+ struct device_state *dev_state;
+
+ might_sleep();
+
+ pasid_state = mn_to_state(mn);
+ dev_state = pasid_state->device_state;
+
+ if (pasid_state->device_state->inv_ctx_cb)
+ dev_state->inv_ctx_cb(dev_state->pdev, pasid_state->pasid);
+
+ unbind_pasid(dev_state, pasid_state->pasid);
+}
+
static struct mmu_notifier_ops iommu_mn = {
+ .release = mn_release,
.clear_flush_young = mn_clear_flush_young,
.change_pte = mn_change_pte,
.invalidate_page = mn_invalidate_page,
@@ -618,53 +635,6 @@ 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;
-
- if (pasid_state->device_state->inv_ctx_cb)
- dev_state->inv_ctx_cb(dev_state->pdev, 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)
{
@@ -739,6 +709,7 @@ EXPORT_SYMBOL(amd_iommu_bind_pasid);
void amd_iommu_unbind_pasid(struct pci_dev *pdev, int pasid)
{
+ struct pasid_state *pasid_state;
struct device_state *dev_state;
u16 devid;
@@ -755,7 +726,17 @@ void amd_iommu_unbind_pasid(struct pci_dev *pdev, int pasid)
if (pasid < 0 || pasid >= dev_state->max_pasids)
goto out;
- unbind_pasid(dev_state, pasid);
+ pasid_state = get_pasid_state(dev_state, pasid);
+ if (pasid_state == NULL)
+ goto out;
+ /*
+ * Drop reference taken here. We are safe because we still hold
+ * the reference taken in the amd_iommu_bind_pasid function.
+ */
+ put_pasid_state(pasid_state);
+
+ /* This will call the mn_release function and unbind the PASID */
+ mmu_notifier_unregister(&pasid_state->mn, pasid_state->mm);
out:
put_device_state(dev_state);
@@ -961,7 +942,6 @@ static int __init amd_iommu_v2_init(void)
goto out_destroy_wq;
amd_iommu_register_ppr_notifier(&ppr_nb);
- profile_event_register(PROFILE_TASK_EXIT, &profile_nb);
return 0;
@@ -980,7 +960,6 @@ static void __exit amd_iommu_v2_exit(void)
if (!amd_iommu_v2_supported())
return;
- profile_event_unregister(PROFILE_TASK_EXIT, &profile_nb);
amd_iommu_unregister_ppr_notifier(&ppr_nb);
flush_workqueue(iommu_wq);
--
1.7.9.5
--
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