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 3EBD9ECDE32 for ; Wed, 17 Oct 2018 06:54:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF114214C3 for ; Wed, 17 Oct 2018 06:54:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF114214C3 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 S1727461AbeJQOst (ORCPT ); Wed, 17 Oct 2018 10:48:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48726 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727162AbeJQOss (ORCPT ); Wed, 17 Oct 2018 10:48:48 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6B7B9C05D3EC; Wed, 17 Oct 2018 06:54:36 +0000 (UTC) Received: from [10.72.12.94] (ovpn-12-94.pek2.redhat.com [10.72.12.94]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4ED6326DE5; Wed, 17 Oct 2018 06:54:25 +0000 (UTC) Subject: Re: [PATCH net-next V2 6/8] vhost: packed ring support To: Maxime Coquelin , "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 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> <447f47fa-32dd-a408-dd81-13a9839e0748@redhat.com> <1df62bd3-3cc9-d04a-2939-4570d37faa68@redhat.com> From: Jason Wang Message-ID: <0f3827e5-a7fa-e54a-725d-7726e90333b8@redhat.com> Date: Wed, 17 Oct 2018 14:54:22 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1df62bd3-3cc9-d04a-2939-4570d37faa68@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 17 Oct 2018 06:54:36 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/10/16 下午9:58, Maxime Coquelin wrote: > > On 10/15/2018 04:22 AM, Jason Wang wrote: >> >> >> 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. > > I'm fine to put wrap_counter at bit 15. > I will post a new version of the DPDK series soon. > >> Btw the code assumes used_wrap_counter is equal to avail_wrap_counter >> which looks wrong? > > For split ring, we used to set the last_used_idx to the same value as > last_avail_idx as VHOST_USER_GET_VRING_BASE cannot be called while the > ring is being processed, so their value is always the same at the time > the request is handled. I may miss something, but it looks to me we should sync last_used_idx from used_idx. Thanks > > > I kept the same behavior for packed ring, and so the wrap counter have > to be the same. > > Regards, > Maxime > >> 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; >>>> [...] >>