On Thu, Feb 16, 2023 at 05:10:06PM +0800, Liu, Yi L wrote: > > From: Zhao, Yan Y <yan.y.zhao@xxxxxxxxx> > > Sent: Thursday, February 16, 2023 4:24 PM > > > > On Mon, Feb 13, 2023 at 07:13:47AM -0800, Yi Liu wrote: > > ... > > > > > +long vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df, > > > + unsigned long arg) > > > +{ > > > + struct vfio_device *device = df->device; > > > + struct vfio_device_bind_iommufd bind; > > > + struct iommufd_ctx *iommufd = NULL; > > > + struct fd f; > > > + unsigned long minsz; > > > + int ret; > > > + > > > + minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid); > > > + > > > + if (copy_from_user(&bind, (void __user *)arg, minsz)) > > > + return -EFAULT; > > > + > > > + if (bind.argsz < minsz || bind.flags) > > > + return -EINVAL; > > > + > > > + if (!device->ops->bind_iommufd) > > > + return -ENODEV; > > > + > > > + ret = vfio_device_claim_group(device); > > > + if (ret) > > > + return ret; > > > + > > > + mutex_lock(&device->dev_set->lock); > > > + /* > > > + * If already been bound to an iommufd, or already set noiommu > > > + * then fail it. > > > + */ > > > + if (df->iommufd || df->noiommu) { > > > + ret = -EINVAL; > > > + goto out_unlock; > > > + } > > > + > > > + /* iommufd < 0 means noiommu mode */ > > > + if (bind.iommufd < 0) { > > > + if (!capable(CAP_SYS_RAWIO)) { > > > + ret = -EPERM; > > > + goto out_unlock; > > > + } > > > + df->noiommu = true; > > > + } else { > > > + f = fdget(bind.iommufd); > > Here, the iommufd file count + 1, > > > > > + if (!f.file) { > > > + ret = -EBADF; > > > + goto out_unlock; > > > + } > > > + iommufd = iommufd_ctx_from_file(f.file); > > iommufd file count + 1, again > > > > > + if (IS_ERR(iommufd)) { > > > + ret = PTR_ERR(iommufd); > > > + goto out_put_file; > > > + } > > > + } > > > + > > > + /* > > > + * Before the device open, get the KVM pointer currently > > > + * associated with the device file (if there is) and obtain a > > > + * reference. This reference is held until device closed. Save > > > + * the pointer in the device for use by drivers. > > > + */ > > > + vfio_device_get_kvm_safe(df); > > > + > > > + df->iommufd = iommufd; > > > + ret = vfio_device_open(df, &bind.out_devid, NULL); > > iommufd file count + 1 in iommufd_device_bind for first open. > > > > > + if (ret) > > > + goto out_put_kvm; > > > + > > > + ret = copy_to_user((void __user *)arg + > > > + offsetofend(struct vfio_device_bind_iommufd, > > iommufd), > > > + &bind.out_devid, > > > + sizeof(bind.out_devid)) ? -EFAULT : 0; > > > + if (ret) > > > + goto out_close_device; > > > + > > > + if (iommufd) > > > + fdput(f); > > But, only one file count is put. > > Good catch! Yes it is missed. And needs to call iommufd_ctx_put() > in vfio_device_cdev_close() as well. If I read correctly, iommufd_device_bind() in the first open will get the reference through iommufd_ctx_get(ictx) and iommufd_device_destroy() in the last close will do the iommufd_ctx_put(). As vfio_device_ioctl_bind_iommufd() isn't paring with vfio_device_cdev_close(), I think the fix below is simpler :) > > Need a paring iommufd_ctx_put() after a successful > > iommufd_ctx_from_file() > > above to avoid iommufd_fops_release() never being called. > > > > e.g. > > > > @@ -1222,11 +1226,13 @@ static long > > vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df, > > ret = -EBADF; > > goto out_unlock; > > } > > iommufd = iommufd_ctx_from_file(f.file); > > if (IS_ERR(iommufd)) { > > ret = PTR_ERR(iommufd); > > goto out_put_file; > > } > > + iommufd_ctx_put(iommufd); > > Since iommufd is recorded in df, so needs to hold refcount till > df->iommufd=NULL; > > > > } > > > > /* df->kvm is supposed to be set in vfio_device_file_set_kvm() */ > > > > > + else if (df->noiommu) > > > + dev_warn(device->dev, "vfio-noiommu device used by user > > " > > > + "(%s:%d)\n", current->comm, > > task_pid_nr(current)); > > > + mutex_unlock(&device->dev_set->lock); > > > + return 0; > > > + > > > +out_close_device: > > > + vfio_device_close(df); > > > +out_put_kvm: > > > + df->iommufd = NULL; > > > + df->noiommu = false; > > > + vfio_device_put_kvm(device); > > > +out_put_file: > > > + if (iommufd) > > > + fdput(f); > > > +out_unlock: > > > + mutex_unlock(&device->dev_set->lock); > > > + vfio_device_release_group(device); > > > + return ret; > > > +} > > > +