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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 994BEC433EF for ; Mon, 6 Sep 2021 06:38:02 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4B8986056B for ; Mon, 6 Sep 2021 06:38:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4B8986056B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 2E44680D88; Mon, 6 Sep 2021 06:38:00 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ns9w6Abh8IDB; Mon, 6 Sep 2021 06:37:59 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp1.osuosl.org (Postfix) with ESMTPS id 6817E80D5A; Mon, 6 Sep 2021 06:37:45 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6A6C2C0021; Mon, 6 Sep 2021 06:37:26 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 62070C0020 for ; Mon, 6 Sep 2021 06:37:25 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 4F8EC60619 for ; Mon, 6 Sep 2021 06:37:21 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp3.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=redhat.com Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id q9sdwK1ECHjM for ; Mon, 6 Sep 2021 06:37:18 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by smtp3.osuosl.org (Postfix) with ESMTPS id A4BF7605F6 for ; Mon, 6 Sep 2021 06:37:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1630910233; 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: in-reply-to:in-reply-to:references:references; bh=NwUBcFLW2DErKP8nW3thbj1Bfk3yLnGU+eP2iS4eEBM=; b=TGHqg2CyHya/cDMgqzBJO5kzBsaq9hLPnHy15h6up+WMsQmb+rfk22we1Pojh3mlveMUqn Uifyp4crzsgZ+JGSl2xU9Ob3a/ppqGVf6KU2u1rXs7irtjCTcchFHJ6YQ81aQKSQMMOSSv Gstdy5A/awreNUUG6oV5bUWL0GoiqKE= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-236-LkIUI--lPJysbrTq1W4Mhw-1; Mon, 06 Sep 2021 02:37:11 -0400 X-MC-Unique: LkIUI--lPJysbrTq1W4Mhw-1 Received: by mail-wm1-f71.google.com with SMTP id m16-20020a7bca50000000b002ee5287d4bfso2838455wml.7 for ; Sun, 05 Sep 2021 23:37:10 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=NwUBcFLW2DErKP8nW3thbj1Bfk3yLnGU+eP2iS4eEBM=; b=fMWriSUi+u42oHdiT/97szR7M6dDJo9oXEvLeLBbR2HKDPnILzhtB8cCA2BcRAg+jS uxjIABubm/+ocnRZdy+5AJpMgw1ucr5tbUdaJprhDONkXrPg3BLhZtkQY+qQgyJU+mk2 RxSvBa5isgOFouVO3pfTYXZrspmrCUweE+UC2ZsmZ7ZySr6VAIFWoWxwJNlvSz9x4W5P PrS5yRiNV8t1sWezOcqQTPYRutTAhkZ6T5l7beTcQEEUNv9kq5+OfO9ARfIxS02wMPDZ oaiI8e4i7Jo9viKtmJCfpq0cwor4mf2mulYd6gR2Vb9vbLZgYVJxAmSaMyhiHM+MgY+4 Wczw== X-Gm-Message-State: AOAM531GJY1G758h42eESZDBdgKV5CQAxX+UV8EHwzBajxlwTiFuv63E HEnzAbYBCndwASVB4FrQHC1Heo87WgSvJNjADQK7WfrY3Dq962Xxc+uwjTaimkHI2Kb6W7vjI7w ouN6Qy/E+QcRZ8dFLu/zwJNvYLvNC7g== X-Received: by 2002:a1c:1f8e:: with SMTP id f136mr9990703wmf.132.1630910229808; Sun, 05 Sep 2021 23:37:09 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyRCwrPqlTT9EQxN6i2JahNEijC2yzlB8bw+tqErn2HIqi0obsj9A8iduK7E+CvdT1s7MMNSQ== X-Received: by 2002:a1c:1f8e:: with SMTP id f136mr9990653wmf.132.1630910229544; Sun, 05 Sep 2021 23:37:09 -0700 (PDT) Received: from redhat.com ([2.55.131.183]) by smtp.gmail.com with ESMTPSA id g1sm8586151wrb.27.2021.09.05.23.37.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 05 Sep 2021 23:37:08 -0700 (PDT) Date: Mon, 6 Sep 2021 02:37:03 -0400 From: "Michael S. Tsirkin" To: Yongji Xie Subject: Re: [PATCH v13 05/13] vdpa: Add reset callback in vdpa_config_ops Message-ID: <20210906023131-mutt-send-email-mst@kernel.org> References: <20210831103634.33-1-xieyongji@bytedance.com> <20210831103634.33-6-xieyongji@bytedance.com> <20210906015524-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: kvm , Jason Wang , virtualization , Christian Brauner , Will Deacon , Jonathan Corbet , Matthew Wilcox , Christoph Hellwig , Dan Carpenter , Stefano Garzarella , Liu Xiaodong , linux-fsdevel@vger.kernel.org, Al Viro , Stefan Hajnoczi , songmuchun@bytedance.com, Jens Axboe , He Zhe , Greg KH , Randy Dunlap , linux-kernel , iommu@lists.linux-foundation.org, bcrl@kvack.org, netdev@vger.kernel.org, Joe Perches , Robin Murphy , Mika =?iso-8859-1?Q?Penttil=E4?= X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Mon, Sep 06, 2021 at 02:09:25PM +0800, Yongji Xie wrote: > On Mon, Sep 6, 2021 at 1:56 PM Michael S. Tsirkin wrote: > > > > On Tue, Aug 31, 2021 at 06:36:26PM +0800, Xie Yongji wrote: > > > This adds a new callback to support device specific reset > > > behavior. The vdpa bus driver will call the reset function > > > instead of setting status to zero during resetting. > > > > > > Signed-off-by: Xie Yongji > > > > > > This does gloss over a significant change though: > > > > > > > --- > > > @@ -348,12 +352,12 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev) > > > return vdev->dma_dev; > > > } > > > > > > -static inline void vdpa_reset(struct vdpa_device *vdev) > > > +static inline int vdpa_reset(struct vdpa_device *vdev) > > > { > > > const struct vdpa_config_ops *ops = vdev->config; > > > > > > vdev->features_valid = false; > > > - ops->set_status(vdev, 0); > > > + return ops->reset(vdev); > > > } > > > > > > static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features) > > > > > > Unfortunately this breaks virtio_vdpa: > > > > > > static void virtio_vdpa_reset(struct virtio_device *vdev) > > { > > struct vdpa_device *vdpa = vd_get_vdpa(vdev); > > > > vdpa_reset(vdpa); > > } > > > > > > and there's no easy way to fix this, kernel can't recover > > from a reset failure e.g. during driver unbind. > > > > Yes, but it should be safe with the protection of software IOTLB even > if the reset() fails during driver unbind. > > Thanks, > Yongji Hmm. I don't see it. What exactly will happen? What prevents device from poking at memory after reset? Note that dma unmap in e.g. del_vqs happens too late. And what about e.g. interrupts? E.g. we have this: /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */ vblk->vdev = NULL; and this is no longer true at this point. -- MST _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu