Commit 50d63b5b authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Alex Williamson
Browse files

vfio: Change vfio_external_user_iommu_id() to vfio_file_iommu_group() 



The only caller wants to get a pointer to the struct iommu_group
associated with the VFIO group file. Instead of returning the group ID
then searching sysfs for that string to get the struct iommu_group just
directly return the iommu_group pointer already held by the vfio_group
struct.

It already has a safe lifetime due to the struct file kref, the vfio_group
and thus the iommu_group cannot be destroyed while the group file is open.

Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarYi Liu <yi.l.liu@intel.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v3-f7729924a7ea+25e33-vfio_kvm_no_group_jgg@nvidia.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent d55d9e7a

drivers/vfio/vfio.c

+14 −7
Original line number Diff line number Diff line
@@ -1653,10 +1653,7 @@ static const struct file_operations vfio_device_fops = { 
 * increments the container user counter to prevent

 * the VFIO group from disposal before KVM exits.

 *

 * 3. The external user calls vfio_external_user_iommu_id()

 * to know an IOMMU ID.

 *

 * 4. When the external KVM finishes, it calls

 * 3. When the external KVM finishes, it calls

 * vfio_group_put_external_user() to release the VFIO group.

 * This call decrements the container user counter.

 */
@@ -1697,11 +1694,21 @@ bool vfio_external_group_match_file(struct vfio_group *test_group, 
}

EXPORT_SYMBOL_GPL(vfio_external_group_match_file);



int vfio_external_user_iommu_id(struct vfio_group *group)

/**

 * vfio_file_iommu_group - Return the struct iommu_group for the vfio group file

 * @file: VFIO group file

 *

 * The returned iommu_group is valid as long as a ref is held on the file.

 */

struct iommu_group *vfio_file_iommu_group(struct file *file)

{

	return iommu_group_id(group->iommu_group);

	struct vfio_group *group = file->private_data;



	if (file->f_op != &vfio_group_fops)

		return NULL;

	return group->iommu_group;

}

EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);

EXPORT_SYMBOL_GPL(vfio_file_iommu_group);



long vfio_external_check_extension(struct vfio_group *group, unsigned long arg)

{

include/linux/vfio.h

+1 −1
Original line number Diff line number Diff line
@@ -140,7 +140,7 @@ 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 struct iommu_group *vfio_file_iommu_group(struct file *file);

extern long vfio_external_check_extension(struct vfio_group *group,

					  unsigned long arg);

virt/kvm/vfio.c

+12 −25
Original line number Diff line number Diff line
@@ -108,43 +108,31 @@ static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group) 
}



#ifdef CONFIG_SPAPR_TCE_IOMMU

static int kvm_vfio_external_user_iommu_id(struct vfio_group *vfio_group)

static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)

{

	int (*fn)(struct vfio_group *);

	int ret = -EINVAL;

	struct iommu_group *(*fn)(struct file *file);

	struct iommu_group *ret;



	fn = symbol_get(vfio_external_user_iommu_id);

	fn = symbol_get(vfio_file_iommu_group);

	if (!fn)

		return ret;

		return NULL;



	ret = fn(vfio_group);

	ret = fn(file);



	symbol_put(vfio_external_user_iommu_id);

	symbol_put(vfio_file_iommu_group);



	return ret;

}



static struct iommu_group *kvm_vfio_group_get_iommu_group(

		struct vfio_group *group)

{

	int group_id = kvm_vfio_external_user_iommu_id(group);



	if (group_id < 0)

		return NULL;



	return iommu_group_get_by_id(group_id);

}



static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,

		struct vfio_group *vfio_group)

					     struct kvm_vfio_group *kvg)

{

	struct iommu_group *grp = kvm_vfio_group_get_iommu_group(vfio_group);

	struct iommu_group *grp = kvm_vfio_file_iommu_group(kvg->file);



	if (WARN_ON_ONCE(!grp))

		return;



	kvm_spapr_tce_release_iommu_group(kvm, grp);

	iommu_group_put(grp);

}

#endif
@@ -258,7 +246,7 @@ static int kvm_vfio_group_del(struct kvm_device *dev, unsigned int fd) 
		list_del(&kvg->node);

		kvm_arch_end_assignment(dev->kvm);

#ifdef CONFIG_SPAPR_TCE_IOMMU

		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);

		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg);

#endif

		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);

		kvm_vfio_group_put_external_user(kvg->vfio_group);
@@ -304,7 +292,7 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev, 
		if (kvg->file != f.file)

			continue;



		grp = kvm_vfio_group_get_iommu_group(kvg->vfio_group);

		grp = kvm_vfio_file_iommu_group(kvg->file);

		if (WARN_ON_ONCE(!grp)) {

			ret = -EIO;

			goto err_fdput;
@@ -312,7 +300,6 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev, 


		ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,

						       grp);

		iommu_group_put(grp);

		break;

	}
@@ -388,7 +375,7 @@ static void kvm_vfio_destroy(struct kvm_device *dev) 


	list_for_each_entry_safe(kvg, tmp, &kv->group_list, node) {

#ifdef CONFIG_SPAPR_TCE_IOMMU

		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);

		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg);

#endif

		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);

		kvm_vfio_group_put_external_user(kvg->vfio_group);