Commit a40d4c67 authored by Joerg Roedel's avatar Joerg Roedel
Browse files

iommu/amd: Implement mmu_notifier_release call-back 



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: default avatarJoerg Roedel <jroedel@suse.de>
Tested-by: default avatarJay Cornwall <Jay.Cornwall@amd.com>
parent 741669c7

drivers/iommu/amd_iommu_v2.c

+35 −56
Original line number Diff line number Diff line
@@ -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,
@@ -620,53 +637,6 @@ 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)

{
@@ -741,6 +711,7 @@ 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;
@@ -757,7 +728,17 @@ 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);
@@ -963,7 +944,6 @@ 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;
@@ -982,7 +962,6 @@ 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);

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