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Commit 5d6dee80 authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: New external user group/file match 



At the point where the kvm-vfio pseudo device wants to release its
vfio group reference, we can't always acquire a new reference to make
that happen.  The group can be in a state where we wouldn't allow a
new reference to be added.  This new helper function allows a caller
to match a file to a group to facilitate this.  Given a file and
group, report if they match.  Thus the caller needs to already have a
group reference to match to the file.  This allows the deletion of a
group without acquiring a new reference.

Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Tested-by: default avatarEric Auger <eric.auger@redhat.com>
Cc: stable@vger.kernel.org
parent e323369b

drivers/vfio/vfio.c

+9 −0
Original line number Diff line number Diff line
@@ -1776,6 +1776,15 @@ void vfio_group_put_external_user(struct vfio_group *group) 
}

EXPORT_SYMBOL_GPL(vfio_group_put_external_user);



bool vfio_external_group_match_file(struct vfio_group *test_group,

				    struct file *filep)

{

	struct vfio_group *group = filep->private_data;



	return (filep->f_op == &vfio_group_fops) && (group == test_group);

}

EXPORT_SYMBOL_GPL(vfio_external_group_match_file);



int vfio_external_user_iommu_id(struct vfio_group *group)

{

	return iommu_group_id(group->iommu_group);

include/linux/vfio.h

+2 −0
Original line number Diff line number Diff line
@@ -97,6 +97,8 @@ extern void vfio_unregister_iommu_driver( 
 */

extern struct vfio_group *vfio_group_get_external_user(struct file *filep);

extern void vfio_group_put_external_user(struct vfio_group *group);

extern bool vfio_external_group_match_file(struct vfio_group *group,

					   struct file *filep);

extern int vfio_external_user_iommu_id(struct vfio_group *group);

extern long vfio_external_check_extension(struct vfio_group *group,

					  unsigned long arg);

virt/kvm/vfio.c

+19 −8
Original line number Diff line number Diff line
@@ -51,6 +51,22 @@ static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep) 
	return vfio_group;

}



static bool kvm_vfio_external_group_match_file(struct vfio_group *group,

					       struct file *filep)

{

	bool ret, (*fn)(struct vfio_group *, struct file *);



	fn = symbol_get(vfio_external_group_match_file);

	if (!fn)

		return false;



	ret = fn(group, filep);



	symbol_put(vfio_external_group_match_file);



	return ret;

}



static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)

{

	void (*fn)(struct vfio_group *);
@@ -231,18 +247,13 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) 
		if (!f.file)

			return -EBADF;



		vfio_group = kvm_vfio_group_get_external_user(f.file);

		fdput(f);



		if (IS_ERR(vfio_group))

			return PTR_ERR(vfio_group);



		ret = -ENOENT;



		mutex_lock(&kv->lock);



		list_for_each_entry(kvg, &kv->group_list, node) {

			if (kvg->vfio_group != vfio_group)

			if (!kvm_vfio_external_group_match_file(kvg->vfio_group,

								f.file))

				continue;



			list_del(&kvg->node);
@@ -260,7 +271,7 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) 


		mutex_unlock(&kv->lock);



		kvm_vfio_group_put_external_user(vfio_group);

		fdput(f);



		kvm_vfio_update_coherency(dev);