From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 461FDC6787C for ; Fri, 12 Oct 2018 17:23:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19A0F21470 for ; Fri, 12 Oct 2018 17:23:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 19A0F21470 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727631AbeJMA5Y (ORCPT ); Fri, 12 Oct 2018 20:57:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41458 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726761AbeJMA5X (ORCPT ); Fri, 12 Oct 2018 20:57:23 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2CC4940F2B; Fri, 12 Oct 2018 17:23:53 +0000 (UTC) Received: from redhat.com (ovpn-124-120.rdu2.redhat.com [10.10.124.120]) by smtp.corp.redhat.com (Postfix) with SMTP id 7ECAC60CD3; Fri, 12 Oct 2018 17:23:47 +0000 (UTC) Date: Fri, 12 Oct 2018 13:23:46 -0400 From: "Michael S. Tsirkin" To: Tiwei Bie Cc: Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, wexu@redhat.com, jfreimann@redhat.com, maxime.coquelin@redhat.com Subject: Re: [PATCH net-next V2 6/8] vhost: packed ring support Message-ID: <20181012131812-mutt-send-email-mst@kernel.org> References: <1531711691-6769-1-git-send-email-jasowang@redhat.com> <1531711691-6769-7-git-send-email-jasowang@redhat.com> <20181012143244.GA28400@debian> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181012143244.GA28400@debian> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 12 Oct 2018 17:23:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 12, 2018 at 10:32:44PM +0800, Tiwei Bie wrote: > On Mon, Jul 16, 2018 at 11:28:09AM +0800, Jason Wang wrote: > [...] > > @@ -1367,10 +1397,48 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg > > vq->last_avail_idx = s.num; > > /* Forget the cached index value. */ > > vq->avail_idx = vq->last_avail_idx; > > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) { > > + vq->last_avail_wrap_counter = wrap_counter; > > + vq->avail_wrap_counter = vq->last_avail_wrap_counter; > > + } > > break; > > case VHOST_GET_VRING_BASE: > > s.index = idx; > > s.num = vq->last_avail_idx; > > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) > > + s.num |= vq->last_avail_wrap_counter << 31; > > + if (copy_to_user(argp, &s, sizeof(s))) > > + r = -EFAULT; > > + break; > > + case VHOST_SET_VRING_USED_BASE: > > + /* Moving base with an active backend? > > + * You don't want to do that. > > + */ > > + if (vq->private_data) { > > + r = -EBUSY; > > + break; > > + } > > + if (copy_from_user(&s, argp, sizeof(s))) { > > + r = -EFAULT; > > + break; > > + } > > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) { > > + wrap_counter = s.num >> 31; > > + s.num &= ~(1 << 31); > > + } > > + if (s.num > 0xffff) { > > + r = -EINVAL; > > + break; > > + } > > Do we want to put wrap_counter at bit 15? I think I second that - seems to be consistent with e.g. event suppression structure and the proposed extension to driver notifications. > If put wrap_counter at bit 31, the check (s.num > 0xffff) > won't be able to catch the illegal index 0x8000~0xffff for > packed ring. > > > + vq->last_used_idx = s.num; > > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) > > + vq->last_used_wrap_counter = wrap_counter; > > + break; > > + case VHOST_GET_VRING_USED_BASE: > > Do we need the new VHOST_GET_VRING_USED_BASE and > VHOST_SET_VRING_USED_BASE ops? > > We are going to merge below series in DPDK: > > http://patches.dpdk.org/patch/45874/ > > We may need to reach an agreement first. > > > > + s.index = idx; > > + s.num = vq->last_used_idx; > > + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) > > + s.num |= vq->last_used_wrap_counter << 31; > > if (copy_to_user(argp, &s, sizeof s)) > > r = -EFAULT; > > break; > [...]