From nobody Mon Feb 9 21:03:26 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D088721CC46 for ; Mon, 21 Apr 2025 02:45:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745203524; cv=none; b=myWYOmz1EIMBUGNjfN+9BPJx3lbhML48a1CRJzKJCXtObAsqXr+vNpstF843ySQPgsvdovJ4JM2DnTHGxEf7vCfv2/rPg/0HLN9jC5FrsBDmOl243CZqh0HYB+L9Hl5a8ODl//n2+ypkLBJ+smTbNSd0gv33OXp8n+P5F+vRwfY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745203524; c=relaxed/simple; bh=A4Zbqm+MVJZCQcrr+9Ai/1+sO4076QEbyY00hQ6PoxI=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lN8x4j3MwrqwBleQBiNzgxxDA5MF42jSndyJ/2WFjEbR6+1DTaEMxDP5EHVCB/xOcN6EWPd7TqSUBG7Za9fMAp42Ds6Ds8gOn/yFWuBlHEhRk0nSsk8SnyDAErEd0n1hKR2XuGIwXC4Go6E/jws47n8CH66zoVckdsc+ROwmc0I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KSAa8VbM; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KSAa8VbM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745203522; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ss3P3+pIl4el626c6K08/+BeDbxgovbAazzfH4/0Z1Y=; b=KSAa8VbMdx55AVQvQtn2Yj+eia5AkaadYpdWpB1j1Q+D88q5DL7AecHV8IappLMT+HD83v FJrivmVnD2XqNRwFq/yW4XW07/3cGvzJtv3HZsDWD/CIX3O4cUEZ0l6C4GZse2sjWcHCVK 1jBWz6u4Fh2Ua2ZHIUEmDQkykEWcfYM= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-605-anIgpWsfMui2vWWiVhyiuw-1; Sun, 20 Apr 2025 22:45:20 -0400 X-MC-Unique: anIgpWsfMui2vWWiVhyiuw-1 X-Mimecast-MFC-AGG-ID: anIgpWsfMui2vWWiVhyiuw_1745203519 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C18A91800368; Mon, 21 Apr 2025 02:45:19 +0000 (UTC) Received: from server.redhat.com (unknown [10.72.112.29]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id BD7D4180175B; Mon, 21 Apr 2025 02:45:15 +0000 (UTC) From: Cindy Lu To: lulu@redhat.com, jasowang@redhat.com, mst@redhat.com, michael.christie@oracle.com, sgarzare@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v9 3/4] vhost: add VHOST_FORK_FROM_OWNER ioctl and validate inherit_owner Date: Mon, 21 Apr 2025 10:44:09 +0800 Message-ID: <20250421024457.112163-4-lulu@redhat.com> In-Reply-To: <20250421024457.112163-1-lulu@redhat.com> References: <20250421024457.112163-1-lulu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Content-Type: text/plain; charset="utf-8" Add a new UAPI to configure the vhost device to use the kthread mode. The userspace application can use IOCTL VHOST_FORK_FROM_OWNER to choose between owner and kthread mode if necessary. This setting must be applied before VHOST_SET_OWNER, as the worker will be created in the VHOST_SET_OWNER function. In addition, the VHOST_NEW_WORKER requires the inherit_owner setting to be true. So we need to add a check for this. Signed-off-by: Cindy Lu Acked-by: Jason Wang --- drivers/vhost/vhost.c | 29 +++++++++++++++++++++++++++-- include/uapi/linux/vhost.h | 16 ++++++++++++++++ 2 files changed, 43 insertions(+), 2 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index be97028a8baf..fb0c7fb43f78 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1018,6 +1018,13 @@ long vhost_worker_ioctl(struct vhost_dev *dev, unsig= ned int ioctl, switch (ioctl) { /* dev worker ioctls */ case VHOST_NEW_WORKER: + /* + * vhost_tasks will account for worker threads under the parent's + * NPROC value but kthreads do not. To avoid userspace overflowing + * the system with worker threads inherit_owner must be true. + */ + if (!dev->inherit_owner) + return -EFAULT; ret =3D vhost_new_worker(dev, &state); if (!ret && copy_to_user(argp, &state, sizeof(state))) ret =3D -EFAULT; @@ -1134,7 +1141,7 @@ void vhost_dev_reset_owner(struct vhost_dev *dev, str= uct vhost_iotlb *umem) int i; =20 vhost_dev_cleanup(dev); - + dev->inherit_owner =3D true; dev->umem =3D umem; /* We don't need VQ locks below since vhost_dev_cleanup makes sure * VQs aren't running. @@ -2287,7 +2294,25 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned i= nt ioctl, void __user *argp) r =3D vhost_dev_set_owner(d); goto done; } - + if (ioctl =3D=3D VHOST_FORK_FROM_OWNER) { + u8 inherit_owner; + /*inherit_owner can only be modified before owner is set*/ + if (vhost_dev_has_owner(d)) { + r =3D -EBUSY; + goto done; + } + if (copy_from_user(&inherit_owner, argp, sizeof(u8))) { + r =3D -EFAULT; + goto done; + } + if (inherit_owner > 1) { + r =3D -EINVAL; + goto done; + } + d->inherit_owner =3D (bool)inherit_owner; + r =3D 0; + goto done; + } /* You must be the owner to do anything else */ r =3D vhost_dev_check_owner(d); if (r) diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h index b95dd84eef2d..1ae0917bfeca 100644 --- a/include/uapi/linux/vhost.h +++ b/include/uapi/linux/vhost.h @@ -235,4 +235,20 @@ */ #define VHOST_VDPA_GET_VRING_SIZE _IOWR(VHOST_VIRTIO, 0x82, \ struct vhost_vring_state) + +/** + * VHOST_FORK_FROM_OWNER - Set the inherit_owner flag for the vhost device, + * This ioctl must called before VHOST_SET_OWNER. + * + * @param inherit_owner: An 8-bit value that determines the vhost thread m= ode + * + * When inherit_owner is set to 1(default value): + * - Vhost will create tasks similar to processes forked from the owner, + * inheriting all of the owner's attributes. + * + * When inherit_owner is set to 0: + * - Vhost will create tasks as kernel thread. + */ +#define VHOST_FORK_FROM_OWNER _IOW(VHOST_VIRTIO, 0x83, __u8) + #endif --=20 2.45.0