| Message ID | 20170609215952.31986.77344.stgit@gimli.home (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 09/06/2017 23:59, Alex Williamson wrote: > 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: Alex Williamson <alex.williamson@redhat.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> > --- > drivers/vfio/vfio.c | 9 +++++++++ > include/linux/vfio.h | 2 ++ > virt/kvm/vfio.c | 27 +++++++++++++++++++-------- > 3 files changed, 30 insertions(+), 8 deletions(-) > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > index f2e24d5699f2..e6117de60f87 100644 > --- a/drivers/vfio/vfio.c > +++ b/drivers/vfio/vfio.c > @@ -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); > diff --git a/include/linux/vfio.h b/include/linux/vfio.h > index edf9b2cad277..9b34d0af5d27 100644 > --- a/include/linux/vfio.h > +++ b/include/linux/vfio.h > @@ -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); > diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c > index db9036ef8c73..7c14729b1f2c 100644 > --- a/virt/kvm/vfio.c > +++ b/virt/kvm/vfio.c > @@ -47,6 +47,22 @@ 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 *); > @@ -186,18 +202,13 @@ 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); > @@ -211,7 +222,7 @@ 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); > > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Hi, On 09/06/2017 23:59, Alex Williamson wrote: > 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: Alex Williamson <alex.williamson@redhat.com> > Cc: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Thanks Eric > --- > drivers/vfio/vfio.c | 9 +++++++++ > include/linux/vfio.h | 2 ++ > virt/kvm/vfio.c | 27 +++++++++++++++++++-------- > 3 files changed, 30 insertions(+), 8 deletions(-) > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > index f2e24d5699f2..e6117de60f87 100644 > --- a/drivers/vfio/vfio.c > +++ b/drivers/vfio/vfio.c > @@ -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); > diff --git a/include/linux/vfio.h b/include/linux/vfio.h > index edf9b2cad277..9b34d0af5d27 100644 > --- a/include/linux/vfio.h > +++ b/include/linux/vfio.h > @@ -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); > diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c > index db9036ef8c73..7c14729b1f2c 100644 > --- a/virt/kvm/vfio.c > +++ b/virt/kvm/vfio.c > @@ -47,6 +47,22 @@ 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 *); > @@ -186,18 +202,13 @@ 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); > @@ -211,7 +222,7 @@ 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); > >
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index f2e24d5699f2..e6117de60f87 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -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); diff --git a/include/linux/vfio.h b/include/linux/vfio.h index edf9b2cad277..9b34d0af5d27 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -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); diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c index db9036ef8c73..7c14729b1f2c 100644 --- a/virt/kvm/vfio.c +++ b/virt/kvm/vfio.c @@ -47,6 +47,22 @@ 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 *); @@ -186,18 +202,13 @@ 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); @@ -211,7 +222,7 @@ 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);
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: Alex Williamson <alex.williamson@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> --- drivers/vfio/vfio.c | 9 +++++++++ include/linux/vfio.h | 2 ++ virt/kvm/vfio.c | 27 +++++++++++++++++++-------- 3 files changed, 30 insertions(+), 8 deletions(-)