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=-7.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 A1404C49EA7 for ; Thu, 24 Jun 2021 08:14:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86B32600D1 for ; Thu, 24 Jun 2021 08:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231894AbhFXIQd (ORCPT ); Thu, 24 Jun 2021 04:16:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:29559 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231867AbhFXIQb (ORCPT ); Thu, 24 Jun 2021 04:16:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624522452; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QgEPrtgYrjYyuikepQ643R5m9hvqjjuW2YQFdqmgfAI=; b=QV+7Vf1bjADbDhiG+TM4uM7zGPbLLFVmHTCmCa8JNrz4YQUTPAvkO5233621FjkYO24ZUW Yti420ybLptWcqXtRqPUWP9zc/PDKYFpnYN0ei+Y+Y4n5n9Cf41AenOeA5oK9OMkUtVHn/ Lp85ENJoTFLpGGz9plg0aFp/4DsRSIg= Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-360-mKQCNDLYMTmjnis53F6Eow-1; Thu, 24 Jun 2021 04:14:10 -0400 X-MC-Unique: mKQCNDLYMTmjnis53F6Eow-1 Received: by mail-pg1-f200.google.com with SMTP id p2-20020a63e6420000b02902271082c631so495688pgj.5 for ; Thu, 24 Jun 2021 01:14:10 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=QgEPrtgYrjYyuikepQ643R5m9hvqjjuW2YQFdqmgfAI=; b=iyL35rML8mWLnG5UpIKBWJruarxu8X88jZ6gsupRuSYdbbuyShcIksP/WE+ZrznZlg Ji2oQmgNZzUDezHBc/RkrOLOm+26eRLNfRWID8LScK3WGQLgyF+qcV3byUZLAyJB84MU sHMB9UIKjpzwu75kZL2q2gyuk53V4QZKW1meT2FFjkpbW3cQHyv04Vmuk/eusvmOAZTp UK32ovVDV5R+oeJk1Sxagga39VFRIsJzvcE+w4ylrFO+6S2+EphRUuaCAXsTwJgQCRfE xAZo3ZBIdgCKF5Be0x5jy6c77uINWxnq1d3VkLYgoYPt9fyNAQXZIt5/y71FX/7FXmoE +hvw== X-Gm-Message-State: AOAM5300e/57zzDfA0nFANkQP52l4L0MvTPuhARkNNiJN47HkdueYTY6 U/QcvYt0Z8rQrWzDIA6U8a006eTxJFl0qp+SZIrrlvjlVEb7Sst2TyCyOJZQhzDvTC/tQiQ8Us7 DxvUOaf9bqQhX6XKr5IFDSVbmKg== X-Received: by 2002:a63:e04e:: with SMTP id n14mr3633695pgj.324.1624522449547; Thu, 24 Jun 2021 01:14:09 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyfl/37xGZkYh7EyP/rmRN1//BEFW+vjWFYtE33l7LAdc/0dPkEsdVgi/iD6hW3Szw3O6lBHQ== X-Received: by 2002:a63:e04e:: with SMTP id n14mr3633666pgj.324.1624522449288; Thu, 24 Jun 2021 01:14:09 -0700 (PDT) Received: from wangxiaodeMacBook-Air.local ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id v21sm2129727pfu.77.2021.06.24.01.14.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Jun 2021 01:14:08 -0700 (PDT) Subject: Re: [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace To: Yongji Xie Cc: "Michael S. Tsirkin" , Stefan Hajnoczi , Stefano Garzarella , Parav Pandit , Christoph Hellwig , Christian Brauner , Randy Dunlap , Matthew Wilcox , Al Viro , Jens Axboe , bcrl@kvack.org, Jonathan Corbet , =?UTF-8?Q?Mika_Penttil=c3=a4?= , Dan Carpenter , joro@8bytes.org, Greg KH , songmuchun@bytedance.com, virtualization , netdev@vger.kernel.org, kvm , linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel References: <20210615141331.407-1-xieyongji@bytedance.com> <20210615141331.407-10-xieyongji@bytedance.com> <1bba439f-ffc8-c20e-e8a4-ac73e890c592@redhat.com> <0aeb7cb7-58e5-1a95-d830-68edd7e8ec2e@redhat.com> From: Jason Wang Message-ID: <48cab125-093b-2299-ff9c-3de8c7c5ed3d@redhat.com> Date: Thu, 24 Jun 2021 16:13:56 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 在 2021/6/24 下午12:46, Yongji Xie 写道: >> So we need to deal with both FEATURES_OK and reset, but probably not >> DRIVER_OK. >> > OK, I see. Thanks for the explanation. One more question is how about > clearing the corresponding status bit in get_status() rather than > making set_status() fail. Since the spec recommends this way for > validation which is done in virtio_dev_remove() and > virtio_finalize_features(). > > Thanks, > Yongji > I think you can. Or it would be even better that we just don't set the bit during set_status(). I just realize that in vdpa_reset() we had: static inline void vdpa_reset(struct vdpa_device *vdev) {         const struct vdpa_config_ops *ops = vdev->config;         vdev->features_valid = false;         ops->set_status(vdev, 0); } We probably need to add the synchronization here. E.g re-read with a timeout. Thanks