[PATCH 03/10] kvm/vfio: Store the struct file in the kvm_vfio_group

[Jason Gunthorpe <jgg@nvidia.com>]

Following patches will chage the APIs to use the struct file as the handle
instead of the vfio_group, so hang on to a reference to it with the same
duration of as the vfio_group.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 virt/kvm/vfio.c | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 9b942f447df79d..7e1793a1f5f1fd 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -33,6 +33,7 @@ static void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
 
 struct kvm_vfio_group {
 	struct list_head node;
+	struct file *filp;
 	struct vfio_group *vfio_group;
 };
 
@@ -198,23 +199,17 @@ static int kvm_vfio_group_add(struct kvm_device *dev, unsigned int fd)
 	struct kvm_vfio *kv = dev->private;
 	struct vfio_group *vfio_group;
 	struct kvm_vfio_group *kvg;
-	struct fd f;
+	struct file *filp;
 	int ret;
 
-	f = fdget(fd);
-	if (!f.file)
+	filp = fget(fd);
+	if (!filp)
 		return -EBADF;
 
-	vfio_group = kvm_vfio_group_get_external_user(f.file);
-	fdput(f);
-
-	if (IS_ERR(vfio_group))
-		return PTR_ERR(vfio_group);
-
 	mutex_lock(&kv->lock);
 
 	list_for_each_entry(kvg, &kv->group_list, node) {
-		if (kvg->vfio_group == vfio_group) {
+		if (kvg->filp == filp) {
 			ret = -EEXIST;
 			goto err_unlock;
 		}
@@ -226,6 +221,13 @@ static int kvm_vfio_group_add(struct kvm_device *dev, unsigned int fd)
 		goto err_unlock;
 	}
 
+	vfio_group = kvm_vfio_group_get_external_user(filp);
+	if (IS_ERR(vfio_group)) {
+		ret = PTR_ERR(vfio_group);
+		goto err_free;
+	}
+
+	kvg->filp = filp;
 	list_add_tail(&kvg->node, &kv->group_list);
 	kvg->vfio_group = vfio_group;
 
@@ -237,9 +239,11 @@ static int kvm_vfio_group_add(struct kvm_device *dev, unsigned int fd)
 	kvm_vfio_update_coherency(dev);
 
 	return 0;
+err_free:
+	kfree(kvg);
 err_unlock:
 	mutex_unlock(&kv->lock);
-	kvm_vfio_group_put_external_user(vfio_group);
+	fput(filp);
 	return ret;
 }
 
@@ -268,6 +272,7 @@ static int kvm_vfio_group_del(struct kvm_device *dev, unsigned int fd)
 		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);
 		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 		kvm_vfio_group_put_external_user(kvg->vfio_group);
+		fput(kvg->filp);
 		kfree(kvg);
 		ret = 0;
 		break;
@@ -304,10 +309,10 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev,
 		return -EBADF;
 
 	vfio_group = kvm_vfio_group_get_external_user(f.file);
-	fdput(f);
-
-	if (IS_ERR(vfio_group))
-		return PTR_ERR(vfio_group);
+	if (IS_ERR(vfio_group)) {
+		ret = PTR_ERR(vfio_group);
+		goto err_fdput;
+	}
 
 	grp = kvm_vfio_group_get_iommu_group(vfio_group);
 	if (WARN_ON_ONCE(!grp)) {
@@ -320,7 +325,7 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev,
 	mutex_lock(&kv->lock);
 
 	list_for_each_entry(kvg, &kv->group_list, node) {
-		if (kvg->vfio_group != vfio_group)
+		if (kvg->filp != f.file)
 			continue;
 
 		ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
@@ -333,6 +338,8 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev,
 	iommu_group_put(grp);
 err_put_external:
 	kvm_vfio_group_put_external_user(vfio_group);
+err_fdput:
+	fdput(f);
 	return ret;
 }
 
@@ -400,6 +407,7 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
 		kvm_spapr_tce_release_vfio_group(dev->kvm, kvg->vfio_group);
 		kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 		kvm_vfio_group_put_external_user(kvg->vfio_group);
+		fput(kvg->filp);
 		list_del(&kvg->node);
 		kfree(kvg);
 		kvm_arch_end_assignment(dev->kvm);
-- 
2.35.1