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authorAlex Williamson <alex.williamson@redhat.com>2017-06-28 13:50:05 -0600
committerAlex Williamson <alex.williamson@redhat.com>2017-06-28 13:50:05 -0600
commit5d6dee80a1e94cc284d03e06d930e60e8d3ecf7d (patch)
tree58129874a688c31b0c110e85b1af920fd8474018
parente323369b2e204da4dc771bbddceef986f4bf85d5 (diff)
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: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Eric Auger <eric.auger@redhat.com> Cc: stable@vger.kernel.org
-rw-r--r--drivers/vfio/vfio.c9
-rw-r--r--include/linux/vfio.h2
-rw-r--r--virt/kvm/vfio.c27
3 files changed, 30 insertions, 8 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 54dd2fbf83d9..7597a377eb4e 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 6e002d0f3191..d99850c462a1 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -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);