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vfio: Change vfio_external_user_iommu_id() to vfio_file_iommu_group()

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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: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v3-f7729924a7ea+25e33-vfio_kvm_no_group_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Jason Gunthorpe 2022-05-04 16:14:41 -03:00 committed by Alex Williamson
parent d55d9e7a45
commit 50d63b5bbf
3 changed files with 27 additions and 33 deletions
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21
drivers/vfio/vfio.c
View file

@ -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)
{

2
include/linux/vfio.h
View file

@ -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);

37
virt/kvm/vfio.c
View file

@ -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);