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 A98B1C070C3 for ; Mon, 15 Oct 2018 02:22:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E95A20659 for ; Mon, 15 Oct 2018 02:22:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5E95A20659 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 S1726526AbeJOKF5 (ORCPT ); Mon, 15 Oct 2018 06:05:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53552 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726098AbeJOKF5 (ORCPT ); Mon, 15 Oct 2018 06:05:57 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6C60D3084293; Mon, 15 Oct 2018 02:22:49 +0000 (UTC) Received: from [10.72.12.159] (ovpn-12-159.pek2.redhat.com [10.72.12.159]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B6180709A6; Mon, 15 Oct 2018 02:22:35 +0000 (UTC) Subject: Re: [PATCH net-next V2 6/8] vhost: packed ring support To: "Michael S. Tsirkin" , Tiwei Bie Cc: 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 References: <1531711691-6769-1-git-send-email-jasowang@redhat.com> <1531711691-6769-7-git-send-email-jasowang@redhat.com> <20181012143244.GA28400@debian> <20181012131812-mutt-send-email-mst@kernel.org> From: Jason Wang Message-ID: <447f47fa-32dd-a408-dd81-13a9839e0748@redhat.com> Date: Mon, 15 Oct 2018 10:22:33 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181012131812-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Mon, 15 Oct 2018 02:22:49 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018年10月13日 01:23, Michael S. Tsirkin wrote: > 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. Ok, I assumes packed virtqueue support 64K but looks not. I can change it to bit 15 and GET_VRING_BASE need to be changed as well. > > >> 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. >> Do we need to clarify this in the spec? >>> + 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. If we agree that 64K virtqueue won't be supported, I'm ok with either. Btw the code assumes used_wrap_counter is equal to avail_wrap_counter which looks wrong? Thanks >> >>> + 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; >> [...]