kvm/vfio: Store the struct file in the kvm_vfio_group

Following patches will change 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.

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/2-v3-f7729924a7ea+25e33-vfio_kvm_no_group_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 512b3ca..3bd2615 100644 (file)
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -23,6 +23,7 @@
 
 struct kvm_vfio_group {
        struct list_head node;
+       struct file *file;
        struct vfio_group *vfio_group;
 };
 
@@ -186,23 +187,17 @@ 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->file == filp) {
                        ret = -EEXIST;
                        goto err_unlock;
                }
@@ -214,6 +209,13 @@ 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->file = filp;
        list_add_tail(&kvg->node, &kv->group_list);
        kvg->vfio_group = vfio_group;
 
@@ -225,9 +227,11 @@ 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;
 }
 
@@ -258,6 +262,7 @@ static int kvm_vfio_group_del(struct kvm_device *dev, unsigned int fd)
 #endif
                kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
                kvm_vfio_group_put_external_user(kvg->vfio_group);
+               fput(kvg->file);
                kfree(kvg);
                ret = 0;
                break;
@@ -278,10 +283,8 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev,
 {
        struct kvm_vfio_spapr_tce param;
        struct kvm_vfio *kv = dev->private;
-       struct vfio_group *vfio_group;
        struct kvm_vfio_group *kvg;
        struct fd f;
-       struct iommu_group *grp;
        int ret;
 
        if (copy_from_user(&param, arg, sizeof(struct kvm_vfio_spapr_tce)))
@@ -291,36 +294,31 @@ static int kvm_vfio_group_set_spapr_tce(struct kvm_device *dev,
        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);
-
-       grp = kvm_vfio_group_get_iommu_group(vfio_group);
-       if (WARN_ON_ONCE(!grp)) {
-               ret = -EIO;
-               goto err_put_external;
-       }
-
        ret = -ENOENT;
 
        mutex_lock(&kv->lock);
 
        list_for_each_entry(kvg, &kv->group_list, node) {
-               if (kvg->vfio_group != vfio_group)
+               struct iommu_group *grp;
+
+               if (kvg->file != f.file)
                        continue;
 
+               grp = kvm_vfio_group_get_iommu_group(kvg->vfio_group);
+               if (WARN_ON_ONCE(!grp)) {
+                       ret = -EIO;
+                       goto err_fdput;
+               }
+
                ret = kvm_spapr_tce_attach_iommu_group(dev->kvm, param.tablefd,
                                                       grp);
+               iommu_group_put(grp);
                break;
        }
 
        mutex_unlock(&kv->lock);
-
-       iommu_group_put(grp);
-err_put_external:
-       kvm_vfio_group_put_external_user(vfio_group);
+err_fdput:
+       fdput(f);
        return ret;
 }
 #endif
@@ -394,6 +392,7 @@ static void kvm_vfio_destroy(struct kvm_device *dev)
 #endif
                kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
                kvm_vfio_group_put_external_user(kvg->vfio_group);
+               fput(kvg->file);
                list_del(&kvg->node);
                kfree(kvg);
                kvm_arch_end_assignment(dev->kvm);